Podcasts about fe3

"Be the iron fist that keeps your water flowing clean and clear." - Trace Blackmore Welcome back to another insightful Pinks & Blues episode of Scaling UP! H2O! In this episode, host Trace Blackmore dives into the fascinating world of iron in water treatment systems. While iron is essential for life, it can be a major problem in industrial water systems, leading to corrosion, equipment damage, and inefficiencies. This episode unpacks the science behind iron, testing methods, and practical strategies for managing its impact.  Understanding the Iron Triangle  To effectively manage iron in water systems, it's important to understand its different forms. Trace explains the Iron Triangle, breaking down the differences between elemental iron (Fe), ferrous iron (Fe2+), and ferric iron (Fe3+). He discusses how iron moves through water systems and why recognizing these distinctions is critical for water treatment professionals.  How to Test for Iron Accurately  Proper testing is key to managing iron levels. Trace details the phenanthroline method, a common technique used to measure iron concentrations in water. He provides best practices for accurate testing, discusses common interferences like molybdates and nitrites, and explains how to adjust testing methods to ensure reliable results. Corrosion and Iron's Impact on System Longevity  Iron is a major contributor to corrosion in water systems, and Trace explains why steel corrodes so easily. He covers the role of corrosion inhibitors and the importance of filtration systems in preventing excessive iron buildup. By managing iron effectively, professionals can protect equipment, reduce maintenance costs, and improve system efficiency.  Math in Action: Calculating Total Iron in a System  For those who love applying real-world math, Trace walks through the process of calculating total iron in pounds within a system. He explains how this calculation can help justify maintenance decisions and provide a compelling reason for clients to invest in proper water treatment solutions. Takeaways: Why Iron Management Matters  This episode is packed with valuable insights for water professionals looking to improve their approach to iron management. From understanding the science behind iron to implementing better testing and corrosion prevention strategies, this discussion is designed to help you stay ahead in your field.  Have a water treatment question? Want to hear a topic covered in a future Pinks & Blues episode? Submit your ideas at ScalingUpH2O.com/showideas  —your input helps shape future episodes! And remember, iron might be essential for our bodies, but in water systems, it's a force to be reckoned with. Mastering iron control is key to maintaining system efficiency and preventing costly damage. Be the iron fist that keeps your water flowing clean and clear!    Stay engaged, keep learning, and continue scaling up your knowledge!  Timestamps    03:20 – Upcoming Events for Water Treatment Professionals 06:44– Water You Know with James McDonald  09:35 – Trace talks about Iron Historical Figure  15:28 – Iron that's in Water Systems 17:39 – Understanding Corrosion & How It Impacts Your System  18:24 – The Iron Triangle  19:58 – The Phenanthroline Method   Quotes  “Steel is the most recycled material on this planet.”   “If you're treating your tests like a task, you're missing the magic of this industry.” “Iron might be essential for our bodies, but it can be a real troublemaker when it's dissolved in the water in our systems, so don't let iron catch you off guard.”  Connect with Scaling UP! H2O  Submit a show idea: Submit a Show Idea  LinkedIn: in/traceblackmore/  YouTube: @ScalingUpH2O    Click HERE to Download Episode's Discussion Guide     Scaling UP! H2O Resources Mentioned  AWT (Association of Water Technologies)  Scaling UP! H2O Academy video courses  Submit a Show Idea  The Rising Tide Mastermind   How its Made Steel by How it's Made Show   400 Celebrating 2024 and 400 Episodes!  399 Pinks and Blues: The Science of Serial Dilution  397 Pinks and Blues: How to look at your tests    Water You Know with James McDonald  Question: What is a plastic or rubber device that seals the outside of a reverse osmosis membrane against the inside wall of the pressure vessel to prevent feedwater from bypassing around the membrane element? 2025 Events for Water Professionals  Check out our Scaling UP! H2O Events Calendar where we've listed every event Water Treaters should be aware of by clicking HERE. 

Story at-a-glance Iron plays essential roles in brain function, helping transport oxygen and create neurotransmitters, but if excess iron accumulates in brain tissue, it disrupts normal cellular processes Research shows higher iron levels in Alzheimer's patients' brains correlate with cognitive decline severity, suggesting iron buildup directly contributes to disease progression Scientists have revealed that malfunctioning amyloid precursor protein and tau proteins in Alzheimer's disease contribute to iron accumulation, creating a harmful feedback loop that accelerates neuronal damage Through advanced imaging, researchers found an imbalance favoring Fe3+ (ferric iron) over Fe2+ (ferrous iron) in Alzheimer's-affected brains, particularly around amyloid plaques Regular blood donation and monitoring ferritin levels (ideally 20 to 40 ng/mL) help manage iron levels, while adequate copper intake is important for proper iron metabolism

Season 6 kicks off in the deep dark woods: the simplified, post-industrial forests of the world — the only forests that many of us have ever known.Join us as we meet foresters in British Columbia, Vermont, and Scotland, all working to embrace the messy art of ecological forestry. Because if we want our forests to be old growth-ier, we might not be able to just wait and leave them alone. It might mean challenging some assumptions and getting out of our comfort zone, but that's what it'll take to see the forest for the trees.— — —With the voices of Ethan Tapper, Brian Duff, Keith Erickson, and Herb HammondMusic by Thumbug, Spencer W Stuart, Nathan Shubert, and Sunfish Moon LightSee also:FE3.4 - Dama DramaGaliano Conservancy AssociationNNRG's "A Forest of Your Own"FernGully: The Last RainforestFor photos from our time in the ancient old growth, citations, a transcript, and more, click here.– – –

Merhabalar.. Bu yazımızda Amerikan Kalp Cemiyeti (AHA) tarafından yakın zamanda yayınlanmış olan güncellemenin​1​; methemoglobinemi, opioid, organofosfatlar ve karbamatlar konularından bahsedeceğiz. Devam niteliğinde olan bu yazının; Dr. Emre Kudu'nun yazdığı giriş kısmını içeren 1. bölümüne buradan, Dr. Emir Ünal'ın yazdığı Benzodiazepinler, β-Blokerler, Kalsiyum Kanal Blokerleri, Kokain, Siyanür, Digoksin ve Lokal Anestezikleri zehirlenmelerini içeren 2. bölümüne buradan ulaşabilirsiniz. Keyifli okumalar. METHEMOGLOBİNEMİ Edinsel methemoglobinemi, hemoglobin molekülündeki demiri ferröz (Fe2+) durumdan ferrik (Fe3+) duruma oksitleyen bir oksidan stres etkenine maruz kalma sonrasında ortaya çıkar. Ferrik durumdayken, hemoglobin artık oksijeni uç organlara etkili bir şekilde bağlayamaz ve iletemez. Methemoglobinemiye neden olabilen yaygın oksidan stres kaynakları arasında nitratlar, nitritler ve birçok farmasötik madde (örn. dapson, benzokain, fenazopiridin) yer alır. Methemoglobinemili hastalar siyanotik görünebilir, nefes darlığı ve yorgunluktan şikayet edebilirler. Nabız oksimetresinde ölçülen oksijen satürasyonu ile arteriyel kan gazında hesaplanan oksijen satürasyonu arasında sıklıkla fark gözlenir. Orta derecede methemoglobinemi genellikle iyi tolere edilmesine rağmen, şiddetli methemoglobinemi; kardiyovasküler kollapsa ve ölüme yol açabilir.Methemoglobinemi için en yaygın kabul gören tedavi, methemoglobin'i hemoglobine indirgeyen bir kofaktör görevi gören metilen mavisidir. Methemoglobinemi tedavisi için metilen mavisini değerlendiren randomize çalışma yoktur, ancak gözlemsel veriler metilen mavisi uygulamasından sonra tutarlı bir şekilde düzelme veya iyileşme olduğunu göstermektedir. Metilen mavisine ek olarak açıklanan diğer tedavi yöntemleri arasında kan değişimi, hiperbarik oksijen tedavisi ve askorbik asit yer almaktadır. Kardiyak arrest vakalarında methemoglobinemi tedavisini inceleyen hiçbir çalışma yoktur. Öneriye Özgü Destekleyici Metin Gözlemsel çalışmalar ve yayınlanmış vaka raporları, metilen mavisinin methemoglobinemiyi etkili bir şekilde tersine çevirdiğini tutarlı bir şekilde göstermektedir. Metilen mavisi, ABD nüfusunun yaklaşık %2'sinde bulunan glukoz-6-fosfat dehidrogenaz eksikliği olan hastalarda methemoglobinemiyi iyileştirmeyebilir veya hemolize neden olmayabilir. Glukoz-6-fosfat dehidrogenaz aktivite testi nadiren gerçek zamanlı olarak kullanılabilir. Methemoglobinemi tedavisinde kan değişimi başarıyla kullanılmıştır ve metilen mavisinin etkisiz olduğu hastalarda tercih edilebilir. Hiperbarik oksijen tedavisi tek başına ve diğer tedavilerle birlikte kullanılmıştır. Ancak, methemoglobinemi konsantrasyonlarının azalması birkaç saate kadar gecikebilir. Kardiyopulmoner kollaps veya kardiyak arrest durumlarında kullanımı pratik olmayabilir. N-asetilsistein, çift kör çapraz insan gönüllü bir çalışmada sodyum nitrit ile indüklenen methemoglobinemiyi azaltmamıştır. Askorbik asit veya C vitamini, methemoglobinemiyi tedavi etmek için kullanılmıştır. Bununla birlikte, yayınlanan vaka raporlarının çoğu, diğer tedavi yöntemleriyle birlikte kullanıldığını göstermektedir. Etkisi yavaştır ve önemli bir etkiye sahip olması için genellikle birkaç saat boyunca birden fazla doz gerektirir. Askorbik asidin resüsitasyon durumlarında etkili olması muhtemel değildir. OPIOIDLER 2020'de opioid aşırı doz tedavisine yönelik son AHA kılavuzunun yayınlanmasından bu yana, opioid zehirlenmesi salgını Amerika Birleşik Devletleri'nde ve dünya çapında diğer birçok ülkede kötüleşmeye devam etmektedir. ABD Ulusal Sağlık İstatistikleri Merkezi'nden alınan veriler, Nisan 2021'de sona eren 12 aylık dönemde opioidlerden kaynaklanan 75.673 ölümün şaşırtıcı olduğunu ve bir önceki yıla göre yaklaşık %35'lik bir artış olduğunu bildirmektedir. Ölümlerin çoğu kasıtsızdır. Hızla tırmanan bu krizin üstesinden gelmek için etkili birincil önleme, acil tedavi ve ikincil önleme stratejilerine acile...

Banded Iron Formations (BIFs) are a visually striking group of sedimentary rocks that are iron rich and almost exclusively deposited in the Precambrian. Their existence points to a major marine iron cycle that does not operate today. Several theories have been proposed to explain how the BIFs formed. While they all involve the precipitation of ferric (Fe3+) iron hydroxides from the seawater via oxidation of dissolved ferrous (Fe2+) iron that was abundant when the oceans contained very low levels of free oxygen, they disagree as to how this oxidation occurred. In the podcast, Clark Johnson describes how oxidation could have occurred without the presence of abundant free oxygen in the oceans. Clark Johnson is a Professor Emeritus in the Department of Geoscience at the University of Wisconsin-Madison.

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Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.06.28.546962v1?rss=1 Authors: Straumann, N., Combes, B. F., Dean-Ben, X. L., Steernke, R., Gerez, J., Dias, I., Chen, Z., Watts, B., Rostami, I., Shi, K., Rominger, A., Baumann, C. R., Luo, J., Noain, D., Nitsch, R. M., Okamura, N., Razansky, D., Ni, R. Abstract: Background: Abnormal alpha-synuclein and iron accumulation in the brain play an important role in Parkinson's disease (PD). Herein, we aim at visualizing alpha-synuclein inclusions and iron deposition in the brains of M83 (A53T) mouse models of PD in vivo. Methods: Fluorescently labelled pyrimidoindole-derivative THK-565 was characterized by using recombinant fibrils and brains from 10-11 months old M83 mice, which subsequently underwent in vivo concurrent wide-field fluorescence and volumetric multispectral optoacoustic tomography (vMSOT) imaging. The in vivo results were verified against structural and susceptibility weighted imaging (SWI) magnetic resonance imaging (MRI) at 9.4 Tesla and scanning transmission X-ray microscopy (STXM) of perfused brains. Brain slice immunofluorescence and Prussian blue staining were further performed to validate the detection of alpha-synuclein inclusions and iron deposition in the brain, respectively. Results: THK-565 showed increased fluorescence upon binding to recombinant alpha-synuclein fibrils and alpha-synuclein inclusions in post-mortem brain slices from patients with Parkinson's disease and M83 mice. i.v. administration of THK-565 in M83 mice showed higher cerebral retention at 20 and 40 minutes post-injection by wide-field fluorescence compared to non-transgenic littermate mice, in congruence with the vMSOT findings. SWI/phase images and Prussian blue indicated the accumulation of iron deposits in the brains of M83 mice, presumably in the Fe3+ form, as evinced by the STXM results. Conclusion: We demonstrated in vivo mapping of alpha-synuclein by means of non-invasive epifluorescence and vMSOT imaging assisted with a targeted THK-565 label and SWI/STXM identification of iron deposits in M83 mouse brains ex vivo. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Artist Song Time Album Year Falling Edge Experience Innocence 8:38 FE3 2018 Falling Edge I Will Not Comply 10:45 FE3 2018 Falling Edge Gone 11:18 FE3 2018 Falling Edge Moments of Truth 10:29 FE3 2018 Evership Isle of the Broken Tree 27:59:00 Evership2 2018 The Windmill The Tree 23:46 Tribus 2018 Unkh Dreamcatcher 19:52 Innerverse […]

Hoy hablamos en el episodio sobre el abonado del acuario plantado, más concretamente sobre el hierro (Fe3+). Es uno de los micro nutrientes más importantes para en cuidado y desarrollo de tus plantas. Como ya sabéis nosotros utilizamos un sistema de abonado basado en lo que el plantado necesita diariamente y prescindimos de los típicos... (continúa leyendo)

Learn How To Invest like a Pro in 24 Hours with this link https://bit.ly/3jqwsvk My Website https://financialeducationjeremy.com/ Follow me on Instagram - https://www.instagram.com/financialeducationjeremy Link to join us in StockHub https://financialeducationjeremy.com/stock-hubThis is where you can chat for free with other investors in the stock market about stocks or things going on in the market. Enjoy!  Welcome in to a NOW rare video on FE3!  I will be talking to you about why investing early is so important!  I will show you various examples of why investing early, picking your own stocks, and the money you put it in is so important in investing!  The stock market will help your money grow but if you put in the effort your money will sky rocket! Hope you enjoy this video!  It is a value packed video and I hope you appreciate it!  If you do smash the thumbs up button!  Subscribe to the Channel for more videos like this!  Leave me a comment with your thoughts on this video! and let me know what stocks to buy now. Financial EducationThis is a Jeremy Lefebvre ProductionCreated by Jeremy Lefebvre LMK if you know any stocks to buy now or stocks to watch!

Sometimes it feels like we're all living in a garbageosphere – an ecosystem of trash and detritus. But despite the extent of anthropogenic impacts, life is resilient and infinitely creative. Hyper-ecologies, novel ecosystems, freakosystems – different names for the same thing: never-before-seen assemblies of lifeforms, born of human disturbance. These profoundly weird ecologies are persistent, and (through a certain lens) often functional. In this final chapter of "Nature, by Design?", we meet again with Oliver Kellhammer and Eric Higgs to discuss what we can learn from these ruderal places, and how they can empower a new way of thinking about ecological restoration. This episode is the last in a 3-part series. Before listening to this one, you may want to catch up with Part 1: Taking the Neo-Eoscenic Route [https://www.futureecologies.net/listen/fe-3-1-nature-by-design-pt1 (FE3.1)] & Part 2: The Path to the Wilderness Lodge [https://www.futureecologies.net/listen/fe-3-2-nature-by-design-pt2 (FE3.2)] – – – For musical credits, citations, and more, https://www.futureecologies.net/listen/fe-3-3-nature-by-design-pt3 (click here.) https://www.futureecologies.net/transcript-guidelines (Please consider adopting an episode for transcription) https://www.patreon.com/futureecologies (Support the show and join our Patreon community) Support this podcast

This episode is the second in a 3-part series. Before listening to this one, you may want to catch up with https://www.futureecologies.net/listen/fe-3-1-nature-by-design-pt1 (FE3.1 - Nature, by Design? Part 1: Taking the Neo-Eoscenic Route) As we continue to discuss the practice of ecological restoration, an important question emerges: is wilderness itself an illusion? We all have a picture of wilderness in our minds, but how did that image come to be? Join us for a tale of two simulacra. For musical credits, citations, and more, https://www.futureecologies.net/listen/fe-3-1-nature-by-design-pt2 (click here.) https://www.futureecologies.net/transcript-guidelines (Please consider adopting an episode for transcription) https://www.patreon.com/futureecologies (Support the show and join our Patreon community) Support this podcast

On today's episode we talk about: Min Min (!), Some pokemon rick rolling, Neil talks about the Bloodstained raindomizer and some FE3 first impressions AND to round things off we talk about our sacred stones draft. Enjoy!

In this episode we cover that rare but fun element to your cyanosed patient Ddx. When your hemoglobin gets oxidized to Fe3+, badness can ensure. Enjoy this quick refresher.

Author: Nick Hatch, M.D. Educational Pearls:   Methemoglobinemia is when the iron in hemoglobin is in the Fe3+ (ferric) state rather than the normal Fe2+  (ferrous) state. Methemoglobin cannot release oxygen at the tissues. Symptoms include cyanosis, headache, tachycardia, dyspnea, and lethargy. Suspect in setting of hypoxia that does not improve with oxygenation, and clinical cyanosis with a normal PaO2 on ABG. Treatment is methylene blue which reduces the iron back to the ferrous state. Causes can be Dapsone, Lidocaine, Benzocaine.   References: Agarwal N, Nagel RL, Prchal JT. Dyshemoglobinemias. In: Disorders of Hemoglobin: Genetics, Pathophysiology, and Clinical Management, 2nd ed, Steinberg M (Ed), 2009. P.607 Cortazzo JA, Lichtman AD. (2014). Methemoglobinemia: a review and recommendations for management. Journal of Cardiothoracic and Vascular Anesthesia. 28:1043. Darling R, Roughton F. (1942). The effect of methemoglobin on the equilibrium between oxygen and hemoglobin. American Journal of Physiology. 137:56.

Many problems caused by bacterial biofilms can be traced back to their high resilience towards chemical perturbations and their extraordinary sturdiness towards mechanical forces. However, the molecular mechanisms that link the mechanical properties of a biofilm with the ability of bacteria to survive in different chemical environments remain enigmatic. Here, we study the erosion stability of Bacillus subtilis (B. subtilis) biofilms in the presence of different chemical environments. We find that these biofilms can utilize the absorption of certain metal ions such as Cu2+, Zn2+, Fe2+, Fe3+ and Al3+ into the biofilm matrix to avoid erosion by shear forces. Interestingly, many of these metal ions are toxic for planktonic B. subtilis bacteria. However, their toxic activity is suppressed when the ions are absorbed into the biofilm matrix. Our experiments clearly demonstrate that the biofilm matrix has to fulfill a dual function, i.e. regulating both the mechanical properties of the biofilm and providing a selective barrier towards toxic chemicals.

We studied seven Itokawa particles provided by the Japan Aerospace Exploration Agency (JAXA) as first International Announcement of Opportunity (AO) study mainly using electron and synchrotron radiation X-ray beam techniques. All the analyzed particles were collected from the first-touchdown site and composed of olivine and plagioclase with traces of Ca phosphate and chromite, and do not contain pyroxenes. Optical microscopy of these particles shows minor undulatory extinction of olivine and plagioclase, suggesting minor shock metamorphism (shock stage: S2). The electron microprobe analysis shows that olivine is Fo(70-73) and plagioclase is An(13-10)Or(5-7). The synchrotron radiation X-ray diffraction (SR-XRD) analysis of olivine crystals gives cell dimensions of a = 4.708 to 4.779 angstrom, b = 10.271 to 10.289 angstrom, c = 6.017 to 6.024 angstrom, corresponding to the Fo content of Fo(similar to 70) by Vegard's law. This composition matches the result obtained by the electron microprobe analysis. The olivine compositions of the analyzed particles are consistent with those of LL chondrites. The cell dimensions of two plagioclase crystals (a = 8.180 to 8.194 angstrom, b = 12.53 to 12.893 angstrom, c = 7.125 to 7.23 angstrom, a = 92.6 degrees to 93.00 degrees, beta = 116.36 degrees to 116.75 degrees, gamma = 90.03 degrees to 90.17 degrees) indicate that their equilibration temperatures are 800 degrees C +/- 10 degrees C. This temperature is near the peak metamorphic temperature recorded by equilibrated ordinary chondrites. The size of plagioclase crystals and the homogeneity of olivine compositions indicate that their petrologic type is >= 5. We also analyzed plagioclase by SR iron X-ray absorption near-edge structure (SR-XANES) and found that its Fe3+/(Fe2+ + Fe3+) ratio is approximately 0.5. Such high Fe3+ abundance indicates the formation under a relatively oxidizing environment. Thus, all these analyses have reconfirmed that the Itokawa particles returned by the Hayabusa spacecraft are very weakly shocked equilibrated LL chondrites, which matches the results of the preliminary examination team.

Matériel : lampe à halogène ou flash, bécher de 600 ml, bâton en verre, éprouvettes de 10 ml et de 5 ml, deux béchers de 150 ml, une cellule de 150 x 10 x 15 mm en verre ou plexiglas, pochoir en carton, lunettes et gants de protection Produits chimiques : Fe(NO3)3 x 9 H2O, acide oxalique, K3[Fe(CN)6] x H2O, Triton®-X-100 (détergent non-ionique, C14H22O(C2H4O)n), Cab-O-Sil® (poudre très fine de dioxyde de silicium) Solution A : 1,2 g Fe(NO3)3 x 9 H2O dans 100 ml d'eau Solution B : 0,8 g d'acide oxalique dans 100 ml d'eau Solution C : 10 ml de solution de K3[Fe(CN)6] x H2O à 3 % Procédure expérimentale : 11 g de poudre de silice (Cab-O-Sil) sont placés dans un bécher de 600 ml, et les solutions A, B et C sont ajoutées. Le mélange est bien remué afin d'obtenir une pâte homogène. Ensuite 3 ml de Triton-X-100 sont introduits. La pâte épaisse jaune est placée dans la cellule recouverte par un pochoir, et l'ensemble est éclairé par la lampe à halogène pour env. 5 secondes. On retire le pochoir, et on voit clairement une coloration bleue aux endroits exposés à la lumière : le mélange des solutions exposé à la lumière intense fait changer la couleur de jaune des complexes fer- acide oxalique vers le bleu intense typique du Bleu de Prusse. Une réaction photochimique est produite qui réduit les ions Fe3+ en ions Fe2+ en oxydant un ion oxalate 2 [Fe(C2O4)3]3– → 2 Fe2+ + 2 CO2 + 5 C2O42– (par réaction photochimique) puis les ions Fe2+ se complexent avec l'hexacyanoferrate (III) K+ + Fe2+ + [Fe(CN)6]3– → K[Fe3+Fe2+(CN)6] Elimination des déchets : les produits sont placés dans un bac pour métaux lourds. H.W. Roesky et W. Möckel, « Chemical Curiosities », page 210, 1996, Copyright Wiley-VCH Verlag GmbH and Co. KGaA. Traduit de l'anglais avec permission.

Background: Fibrillar amyloid-like deposits and co-deposits of tau and alpha-synuclein are found in several common neurodegenerative diseases. Recent evidence indicates that small oligomers are the most relevant toxic aggregate species. While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and alpha-synuclein are not well understood. Results: We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with alpha-synuclein at the level of individual oligomers. We show that Al3+ at physiologically relevant concentrations and tau phosphorylation by GSK-3 beta exert synergistic effects on the formation of a distinct SDS-resistant tau oligomer species even at nanomolar protein concentration. Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of alpha-synuclein in pre-formed tau oligomers. Conclusions: Our findings provide a new perspective on interactions of tau phosphorylation, metal ions, and the formation of potentially toxic oligomer species, and elucidate molecular crosstalks between different aggregation pathways involved in neurodegeneration.

The densities of 10 melts in the CaO-FeO-Fe2O3-SiO2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO2, 14 to 76 wt% Fe2O3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy. Melt densities range from 2.689 to 3.618 gm/cm3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe2O3 and SiO2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe3+. The volume behavior of melts in this system is significantly different from that in the Na2O-FeO-Fe2O3-SiO2 system, consistent with the proposal that a proportion of Fe3+ in melts in the CaO-FeO-Fe2O3-SiO2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence (e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations. The presence of more than one coordination geometry for Fe3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted.

The densities of 12 melts in the Na2O-FeO-Fe2O3-SiO2 system have been determined in equilibrium with air, in the temperature range of 1000–1500°C, using the double bob, Archimedean technique. Ferrous iron determinations of 100–200 mg samples, “dip” quenched from high temperature, indicate that all the melts investigated were highly oxidized under these experimental conditions. 57Fe Mössbauer spectra of glasses obtained by drop quenching 80 mg melt samples from loop equilibration runs yield Fe3+/Fe2+ data equivalent to that for the densitometry (dip) samples for all but the most viscous melt, and confirm that all but one melt equilibrated with air during the densitometry measurements. Melt densities range from 2.17 to 2.88 g/cm3 with a mean standard deviation (from replicate experiments) of 0.36%. Least squares regression of the density data at 1300, 1400 and 1500°C, was calculated, both excluding and including excess volume terms (herein named linear and nonlinear fits, respectively) and the root mean squared deviation (RMSD) of each regression was compared with the total experimental error. The partial molar volumes computed for linear fits for Na2O and SiO2 are similar to those previously reported for melts in the Na2O-Al2O3-SiO2 system (Steinet al., 1986). The partial molar volumes of Fe2O3 obtained in these linear fits are equal to those obtained by Shiraishi et al. (1978) in the FeO-Fe2O3-SiO2 system but 5 to 10% lower than reported by Mo et al. (1982) in multicomponent melts. The partial molar volume exhibited by Fe3+ in this system is representative of the partial molar volume of tetrahedrally coordinated Fe3+ in silicate melts.