Podcasts about Rheology

Rheology is the science that deals with the flow and the strain rate of matter.It's a branch of Physics that studies the origin, the nature and the deformation's characteristics of a matter under the influence of external forces, with particular regard to non-Newtonian liquids. Its main goal is to define the correlations between causes (forces) and effects (deformations and flows), identifying all mechanisms that are the basis of the different rheological behavior on a microscopic and molecular scale.The episode offers an overview about the most important rheological behaviors of ceramic suspensions: barbottine, glaze and grit suspensions, engobes and inks.All these mixtures, in fact, in order to develop a good application and avoid serious problems along the production lines, must be marked by proper rheological features.Which ones?

Ceramic glazes can be applied by means of several technologies but the most common and popular is the airless spray system.However, sometimes glazes can still be discharged on the raw tile by means of bell or vela systems.Each application system required different evaluations about the glaze's rheology.The glaze must be marked by specific properties according to the system with which is applied along the production line. The episode focuses on these differences and on the chemicals that can - or must - be used to get the proper features.At the end, a brief focus on synthetic chemicals, very useful to prevent the proliferation of bacterial attacks before and during application.

Let's go down the Oreo cream rabbit hole!

Ai Live: December 2021: Product Rheology What is Rheology? Why is Rheology important when choosing what filler to use? How are products different? How is cross-linking different?

KSQD 9-15-2021: Comments on an editorial declaring Biology researchers must generate ideas as well as data; The standard lipid panel is not thorough enough to diagnose risks of cardiac disease or validate statin use; The complex physiology and importance of the glycocalyx: the glycolipid and glycoprotein coating of cells and blood vessels; Strange science: Hard water film on the surface of tea makes it taste less bitter; Get a standing desk -- it will help you prevent diabetes; It is never too late to increase health by exercising even if you normally don't; The problem of infection of dental implants; Misplaced interpretation of genetics for schizophrenia; The importance of drinking enough water is especially important as you age

KSQD 9-15-2021: Comments on an editorial declaring Biology researchers must generate ideas as well as data; The standard lipid panel is not thorough enough to diagnose risks of cardiac disease or validate statin use; The complex physiology and importance of the glycocalyx: the glycolipid and glycoprotein coating of cells and blood vessels; Strange science: Hard water film on the surface of tea makes it taste less bitter; Get a standing desk -- it will help you prevent diabetes; It is never too late to increase health by exercising even if you normally don't; The problem of infection of dental implants; Misplaced interpretation of genetics for schizophrenia; The importance of drinking enough water is especially important as you age

Chile, did you know that the earth acts as a large source of electrons and getting in direct contact with the earth can help fight toxins present in the body? Healthy nutrition is not only about the physical substances like food that we ingest, there are other forms of ingesting nutrients such as grounding. If you would like to gain insight on what grounding is and many health benefits it comes with, tune in to this episode with expert cardiologist, Dr. Baxter Montgomery.In this show I'm going to give you a few tips about how grounding can aid blood circulation and therefore, allow your cardiac output to work more effectively, and later we'll be chatting with our expert Dr. Baxter Montgomery who is a Board Certified Cardiologist and founder of the Montgomery Heart & Wellness Center with the mission to reverse and prevent life-threatening illnesses and improve lives using the power of a plant-based diet.Made your best cup of tea yet? Now get comfy, and learn: What is earthing or grounding?Materials that decrease the effects of groundingWhy people ground and why you should too.Decreasing oxidative stress in your body by the antioxidant effect of groundingHow does grounding aid the circulation of blood flow?The relationship between your blood fluidity and cardiac output.Does grounding affect your emotions by reducing stress triggers?The power of meditation as a spiritual and mental ingestionThe benefits of filtering what you let in.Why plant foods are considered superior.The food classification system- healthiest to least healthy.Dr. Montgomery's approach to patients with terminal illness.Why optimal enhancement through nutrition is important.Dr. Montgomery's approach to patients despite the pessimistic nature of the medical community.Dr. Montgomery discusses the wellness programs at Montgomery Heart & WellnessShow linksMontgomery Heart & Wellness HomepageMontgomery Heart & Wellness YouTubeMontgomery Heart & Wellness InstagramMontgomery Heart & Wellness FacebookMontgomery Heart & Wellness LinkedIn

What do the guts of a volcano look like? According to Jonathan Delph, Assistant Professor in the Department of Earth, Atmospheric and Planetary Sciences at Purdue University, it depends on the geoscientist you ask. Delph walks us through several illustrations showing the ways different geoscientific disciplines might view magmatic structure: Geochemistry (process-focused), Petrology (field-focused), and Seismology-focused. Additionally, Delph reveals a recent paradigm shift in scientific thinking about the underground composition of volcanoes.

In this Podcast Episode #1075, Marc Abrahams shows some unfamiliar research studies to fluid dynamicist Nicole Sharp. Dramatic readings and reactions ensue. Remember, our Patreon donors, on most levels, get access to each podcast episode before it is made public. Seth Gliksman, Production Assistant --- Support this podcast: https://anchor.fm/improbableresearch/support

Rheology is in action all around us, from asphalt that doesn't melt on a hot day to perfectly melting chocolate. Foods, motor oils, cosmetics and pharmaceuticals depend on rheological data to perform as expected. This field of science examines the behavior of fluids and materials at different pressures and temperatures, specifically measuring how they flow. Rheology makes products we use every day better, easier to use and safer. You can thank rheology for ketchup that's not runny and lotion that spreads smoothly on your skin. Listen now as SwRI Sr. Research Engineer Dr. Carlos Sanchez discusses rheology, the “go with the flow” science that's everywhere.

Dr. Enrique Saldívar received his medical training in Universidad La Salle, received his MD from Universidad Autonoma de Mexico (UNAM), his Masters in Biomedical Engineering from Universidad Autonoma Metropolitana, and his Ph.D. in Bioengineering from the University of California, San Diego. Throughout his career, he has been appointed faculty at The Scripps Research Institute, La Jolla Bioengineering Institute, The West Wireless Health Institute, and Case Western Reserve University. His expertise includes: Biomechanics, Microcirculation, Rheology, Platelet Engineering, Digital Signal Processing, Image Processing, Bio-Micro-Electro-Mechanical Systems (Bio-MEMS), Nanotechnology, and Digital Health. Dr. Saldívar career in medical devices has focused on the transformation of cutting-edge technological developments into meaningful medical solutions. His multidisciplinary background combined with a deep sense of social responsibility provides him with a unique perspective to provide solutions to unmet medical needs in underserved communities. Dr. Saldivar’s interests are focused on the use of technology to improve the quality of life, globally, and to ameliorate the accessibility to first-class medical attention in underprivileged communities. Dr. Saldívar scientific career has focused on the study of biomechanical mechanisms responsible for complex physiological responses with an emphasis on the rheological mechanisms, at both the cellular level and at the cell membrane level. He has made seminal contributions to the understanding of platelet adhesion under flow and chronic adaptation to extreme hypoxia.

It's the last show of 2020, a year when finding non-COVID science news was like searching for a needle in a viral haystack. This week we've got a bumper edition of our Science of Week quiz, covering news from the whole year, and we're introducing a brand new feature - Animal Etymologies! We're investigating the liquid properties of cats, finding out how fast space junk flies around the Earth, looking at what lasers can tell us about ancient archaeological remains, asking whether we've just made contact with aliens in the next solar system over, stretching the boundaries of animal lengths with siphonophores, and pitching a gritty new sequel to Finding Nemo.If you find some fun science that you think deserves its place on the show, we'd love to hear from you! Get in touch with us at lockdownsciencepodcast@gmail.com!Fardin (2014): https://www.drgoulu.com/wp-content/uploads/2017/09/Rheology-of-cats.pdfSampaio et al (2020): https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3266 Music credit: Blippy Trance Kevin MacLeod (incompetech.com)Licensed under Creative Commons: By Attribution 3.0 Licensehttp://creativecommons.org/licenses/by/3.0/ See acast.com/privacy for privacy and opt-out information.

How come egg and oil will turn into a nice emulsion called mayonnaise when mixed, while water and oil will unavoidably separate into two different phases no matter how vigorously you stir? And is there a way to predict the stability of such phase-mixtures?In this episode of Science on surfaces we talk to Dr Susanna Lauren at Biolin Scientific about interfacial rheology and how this can be used to predict emulsion and foam stability. Susanna did her Ph.D. on superhydrophobic surfaces and microfluidics and she is an expert on surface related phenomena, such as surface tension, wettability, adhesion and interfacial rheology. Susanna explains key terminology such as viscosity, stabilization of interfaces and surface-active molecules, which then leads us to the discussion of how emulsions and foams form. Susanna then moves on to explain in what situations, and why, it is important to be able to measure emulsion and foam stabilities and how this information can be used. She also describes how these measurements can be performed using either of the two approaches of shear- or dilatational methods. Thanks for listening! If you are interested in surface science and related topics, you should also check out our blog - the Surface Science blog

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.27.222802v1?rss=1 Authors: Giubertoni, G., Burla, F., Bakker, H. J., Koenderink, G. Abstract: Many biopolymer hydrogels are environmentally responsive because they are held together by physical associations that depend on pH and temperature. Here we investigate how the pH and temperature response of the rheology of hyaluronan hydrogels is connected to the underlying molecular interactions. Hyaluronan is an essential structural biopolymer in the human body with many applications in biomedicine. Using two-dimensional infrared (2DIR) spectroscopy, we show that hyaluronan chains become connected by hydrogen bonds when the pH is changed from 7.0 to 2.5, and that the bond density at pH 2.5 is independent of temperature. Temperature-dependent rheology measurements show that due to this hydrogen bonding the stress relaxation at pH 2.5 is strongly slowed down in comparison to pH 7.0, consistent with the sticky reptation model of associative polymers. From the flow activation energy we conclude that each polymer is crosslinked by multiple (5-15) hydrogen bonds to others, causing slow macroscopic stress relaxation, despite the short time scale of breaking and reformation of each individual hydrogen bond. Our findings can aid the design of stimuli-responsive hydrogels with tailored viscoelastic properties for biomedical applications. Copy rights belong to original authors. Visit the link for more info

Whew, what a title! In this episode we sit down with Professor Daniel Goldman from the Physics Department at Georgia Tech to discuss how the biomechanics of different organisms interact with complex and dynamic surfaces to enable locomotion. I had to opportunity to tour his lab and speak with each of his graduate students and they are doing some crazy stuff, from supporting NASA with inter-planetary rover design, to building pneumatic millipedes, to robotic particles that interact with each other...cheap, advanced, and 3d printed robots are at the heart of much of the work happening in his CRAB lab (http://crablab.gatech.edu). Shout out about what you like about this episode or others feedback@wewonderpodcast.com --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app --- Send in a voice message: https://anchor.fm/wewonder/message

This week Larry and James return to tell us how they met and to talk donuts, podcasting, Disney+, bad jokes, Rick and Morty, overrunning & overeating on YouTube, and cat physics. Plus James & Mike tour a battleship, and Kevin asks a Thanksgiving Question!

Have you ever wondered how Corry comes up with a wacky new science story every week? This episode we dig into one of the inspirations for the podcast, the Ig Nobel Prize! Having a prize for great scientific achievements is certainly an important thing, but when it comes to the crazy, weird, and wonderful stories (that still make you think) there’s the Ig Nobel Prize! References and Further Reading 1. https://www.improbable.com/ 2. https://www.wired.co.uk/article/wired-awake-140918 3. https://www.drgoulu.com/wp-content/uploads/2017/09/Rheology-of-cats.pdf 4. https://www.google.co.uk/amp/s/amp.theguardian.com/science/2019/sep/13/study-french-postmens-testicles-ig-nobel-winner 5. https://twitter.com/improbresearch?s=20 6. https://www.mentalfloss.com/article/600249/2019-ig-nobel-prize-winners Support us on Patreon: http://patreon.com/SciGuys Watch us on YouTube: http://youtube.com/SciGuys Follow the Sci Guys @notcorry / @jampkin / @lukecutforth

Ig Nobel สาขาชีวิวิทยา 2017 พบแมลงถ้ำ ตัวเมียมีจู๋ ตัวผู้มีจิ๋ม อธิบายเรื่อง Sexual Selection และ Sex Role Reversal BIOLOGY PRIZE [JAPAN, BRAZIL, SWITZERLAND] — Kazunori Yoshizawa, Rodrigo Ferreira, Yoshitaka Kamimura, and Charles Lienhard, for their discovery of a female penis, and a male vagina, in a cave insect. REFERENCE: "Female Penis, Male Vagina and Their Correlated Evolution in a Cave Insect," Kazunori Yoshizawa, Rodrigo L. Ferreira, Yoshitaka Kamimura, Charles Lienhard, Current Biology, vol. 24, no. 9, 2014, pp. 1006-1010. สาขาฟิสิกส์ - มอบให้นักวิจัยผู้ใช้พลศาสตร์ของไหลอธิบายว่าแมวเป็นได้ทั้งของแข็งและของเหลว PHYSICS PRIZE [FRANCE, SINGAPORE, USA] — Marc-Antoine Fardin, for using fluid dynamics to probe the question "Can a Cat Be Both a Solid and a Liquid?" REFERENCE: "On the Rheology of Cats," Marc-Antoine Fardin, Rheology Bulletin, vol. 83, 2, July 2014, pp. 16-17 and 30.   FLUID DYNAMICS PRIZE [SOUTH KOREA, USA] — Jiwon Han, for studying the dynamics of liquid-sloshing, to learn what happens when a person walks backwards while carrying a cup of coffee. REFERENCE: "A Study on the Coffee Spilling Phenomena in the Low Impulse Regime," Jiwon Han, Achievements in the Life Sciences, vol. 10, no. 1, 2016, pp. 87-101. ECONOMICS PRIZE [AUSTRALIA, USA] — Matthew Rockloff and Nancy Greer, for their experiments to see how contact with a live crocodile affects a person's willingness to gamble. REFERENCE: "Never Smile at a Crocodile: Betting on Electronic Gaming Machines is Intensified by Reptile-Induced Arousal," Matthew J. Rockloff and Nancy Greer, Journal of Gambling Studies, vol. 26, no. 4, December 2010, pp. 571-81. ANATOMY PRIZE [UK] — James Heathcote, for his medical research study "Why Do Old Men Have Big Ears?" REFERENCE: "Why Do Old Men Have Big Ears?" James A. Heathcote, British Medical Journal, vol. 311, 1995, p. 1668. NUTRITION PRIZE [BRAZIL, CANADA, SPAIN] — Fernanda Ito, Enrico Bernard, and Rodrigo Torres, for the first scientific report of human blood in the diet of the hairy-legged vampire bat REFERENCE: "What is for Dinner? First Report of Human Blood in the Diet of the Hairy-Legged Vampire Bat Diphylla ecaudata," Fernanda Ito, Enrico Bernard, and Rodrigo A. Torres, Acta Chiropterologica, vol. 18, no. 2, December 2016, pp. 509-515. https://www.youtube.com/watch?v=yNwLfRpNHhI https://www.facebook.com/witcastthailand/posts/1719694678093363

สปอนเซอร์ประจำตอน - IP IDE CEnter facebook.com/IpIdeThailand ศูนย์ให้คำปรึกษาด้านทรัพย์สินทางปัญญาและนวัตกรรม (Intellectual Property Innovation Driven Enterprise Center : IP IDE Center) โดยกรมทรัพย์สินทางปัญญา กระทรวงพาณิชย์ เพื่อสนับสนุนและให้คำปรึกษาด้านธุรกิจนวัตกรรม โดยทีมบุคลากรและผู้เชี่ยวชาญเฉพาะด้าน มุ่งหวังให้ผู้ใช้บริการนำข้อมูล และองค์ความรู้ไปใช้ในการผลิตสินค้าและบริการตามนโยบาย ไทยแลนด์ 4.0 เพื่อสร้างการเจริญเติบโตอย่างยั่งยืน ให้กับเศรษฐกิจและการค้าของไทย นัดหมายรับคำปรึกษา: 02-547-5026 DIP HOT LINE 1368 คลิกอ่าน 7 สิทธิบัตรสุดเพี้ยนจาก Google ประชาสัมพันธ์จากมูลนิธิโลกสีเขียว ประกวดเขียน “เรื่องเล่าสัตว์ป่าคนไม่รัก” ดูรายละเอียดได้ตามลิงค์นี้   รางวัล Ig Nobel ที่พูดถึงในตอน วิดิโอพิธีมอบรางวัล https://www.youtube.com/watch?v=yNwLfRpNHhI วิดิโอเล็คเชอร์พิเศษ (เรื่องดิเจอริดู อยู่นาที 31:34) https://www.youtube.com/watch?v=_6p6Y55yu04&t=1894s สาขาฟิสิกส์ - มอบให้นักวิจัยผู้ใช้พลศาสตร์ของไหลอธิบายว่าแมวเป็นได้ทั้งของแข็งและของเหลว PHYSICS PRIZE [FRANCE, SINGAPORE, USA] — Marc-Antoine Fardin, for using fluid dynamics to probe the question "Can a Cat Be Both a Solid and a Liquid?" REFERENCE: "On the Rheology of Cats," Marc-Antoine Fardin, Rheology Bulletin, vol. 83, 2, July 2014, pp. 16-17 and 30. WHO ATTENDED THE CEREMONY: Marc-Antoine Fardin สาขาสันติภาพ - มอบให้ทีมวิจัยที่สาธิตว่าการเล่น "ดิดเจอริดู" เป็นประจำ ช่วยรักษาโรคนอนกรน (Sleep Apnea) ได้อย่างมีประสิทธิภาพ PEACE PRIZE [SWITZERLAND, CANADA, THE NETHERLANDS, USA] — Milo Puhan, Alex Suarez, Christian Lo Cascio, Alfred Zahn, Markus Heitz, and Otto Braendli, for demonstrating that regular playing of a didgeridoo is an effective treatment for obstructive sleep apnoea and snoring. REFERENCE: "Didgeridoo Playing as Alternative Treatment for Obstructive Sleep Apnoea Syndrome: Randomised Controlled Trial," Milo A. Puhan, Alex Suarez, Christian Lo Cascio, Alfred Zahn, Markus Heitz and Otto Braendli, BMJ, vol. 332 December 2006. WHO ATTENDED THE CEREMONY: Milo Puhan, Christian Lo Cascio, Markus Heitz, Alex Suarez. NOTE: Alex Suarez was the first patient, and was the inspiration for the study. สาขาเศรษฐศาสตร์ - มอบให้ทีมที่ทดลองว่าการจับจระเข้ส่งผลอย่างไรต่อพฤติกรรมการพนัน ECONOMICS PRIZE [AUSTRALIA, USA] — Matthew Rockloff and Nancy Greer, for their experiments to see how contact with a live crocodile affects a person's willingness to gamble. REFERENCE: "Never Smile at a Crocodile: Betting on Electronic Gaming Machines is Intensified by Reptile-Induced Arousal," Matthew J. Rockloff and Nancy Greer, Journal of Gambling Studies, vol. 26, no. 4, December 2010, pp. 571-81. WHO ATTENDED THE CEREMONY: Matthew Rockloff and Nancy Greer   สาขากายวิภาค - มอบให้นักวิจัยผู้ศึกษาว่าทำไมคนแก่ถึงหูใหญ่ ANATOMY PRIZE [UK] — James Heathcote, for his medical research study "Why Do Old Men Have Big Ears?" REFERENCE: "Why Do Old Men Have Big Ears?" James A. Heathcote, British Medical Journal, vol. 311, 1995, p. 1668. WHO ATTENDED THE CEREMONY: James Heathcote   สาขาชีววิทยา - มอบให้กับทีมวิจัยที่ค้นพบแมลงถ้ำซึ่ง ตัวเมียมีจู๋ ตัวผู้มีจิ๋ม BIOLOGY PRIZE [JAPAN, BRAZIL, SWITZERLAND] — Kazunori Yoshizawa, Rodrigo Ferreira, Yoshitaka Kamimura, and Charles Lienhard, for their discovery of a female penis, and a male vagina, in a cave insect. REFERENCE: "Female Penis, Male Vagina and Their Correlated Evolution in a Cave Insect," Kazunori Yoshizawa, Rodrigo L. Ferreira, Yoshitaka Kamimura, Charles Lienhard, Current Biology, vol. 24, no. 9, 2014, pp. 1006-1010. WHO ATTENDED THE CEREMONY: They delivered a short video acceptance speech, filmed in a cave. สาขาพลศาสตร์ของไหล - มอบให้กับผู้ศึกษาการกระฉอกของกาแฟขณะเดินถอยหลัง FLUID DYNAMICS PRIZE [SOUTH KOREA, USA] — Jiwon Han, for studying the dynamics of liquid-sloshing, to learn what happens when a person walks backwards while carrying a cup of coffee. REFERENCE: "A Study on the Coffee Spilling Phenomena in t...

John and Shannon discuss this week’s Mw 7.1 Earthquake in Mexico and talk about the rheology of cats. Earthquake Mw 7.1 Event Mw 8.1 Event 1985 Mexico City Mw 8.0 Lake Texcoco Tuned Mass Damper in Action Fun Paper Friday On the Rheology of Cats," Marc-Antoine Fardin, Rheology Bulletin, vol. 83, 2, July 2014, pp. 16–17 and 30. Contact us: Show - www.dontpanicgeocast.com - SWUNG Slack - @dontpanicgeo - show@dontpanicgeocast.com John Leeman - www.johnrleeman.com - @geo_leeman Shannon Dulin - @ShannonDulin  

Turner, A (University of Oxford) Monday 6th June 2016 - 14:45 to 15:30

Faul, U (Massachusetts Institute of Technology) Tuesday 12th April 2016 - 13:30 to 14:30

You can't walk on water... but you CAN run on it, without sinking. The trick: Non-Newtonian Fluids.

Download Audio File Rheology again? The science of rheology is critical in so much that goes into fluid coating that we could spend a lifetime discussing the details regarding a particular flow regime and still forget to worry about viscoelastic functions that could screw up the entire system. Since [...]

Jop, P Tuesday 02 July 2013, 14:20-14:40

Médale, M; Chauchat, J Wednesday 03 July 2013, 11:40-12:00

Bouzid, M; Trulsson, M; Claudin, P; Clément, E; Andreotti, B Monday 01 July 2013, 16:40-17:00

Volcanic landscapes often present advantages for people who inhabit the surrounding areas, but the increasing numbers of people threatened by potential activity increases as these settlements grow. It is thus of vital importance to glean as much information as possible by monitoring active volcanoes (including seismicity, ground deformation, gas flux and temperature changes). Although volcanic behaviour can be difficult to predict, precursory information can often be identified retrospectively (once an eruption begins) to help link antecedent behaviour to eruption attributes. Likewise, eruption relics can be used to identify processes in pre-eruptive magma. Additionally, a huge amount of information may be gathered through experimentation on rock and magma samples. This study combines field and analytical studies of natural samples from Volcán de Colima (Mexico), Mount St. Helens (USA) and Soufrière Hills (Montserrat) with high-temperature magma deformation experiments to investigate the processes involved with magma ascent during dome-building eruptions (Figure S-1). The study of conduit-dwelling magma is of the utmost importance for understanding transitions from effusive to explosive eruptions. Of primary interest is the rheology of highly crystalline magmas that make up the magma column. Rheology is integrally linked to the composition and textural state (porosity, crystallinity) of magma as well as the stress, temperature and strain rate operative during flow. Many studies have investigated the rheology of multi-phase magmas, but in Chapter 2 this is notably linked to the evolution of the physical properties of the magmas; tracing the changes in porosity, permeability, Poisson’s ratio, Young’s modulus during strain dependent magmatic flow. Especially at high strain rates mechanical degradation of the magma samples may supersede magmatic flow and crystal rearrangement as the dominant form of deformation, resulting in lower apparent viscosities than those anticipated from magmatic state. This leads to an evolution of the fracture network to form inhomogeneous distribution of the permeable porous network; with damage zones cutting through areas of densification. In a conduit setting this is analogous to the formation of a dense, impermeable magma plug which would prohibit degassing through the bulk of the magma. Degassing may or may not proceed along conduit margins, and the plug formation could lead to critical overpressures forming in the conduit and result in highly explosive eruption. During the multi-scale process of strain localisation it is also probable that another previously unforeseen character acts upon magma rheology. Chapter 3 details the first documentation of crystal plasticity in experimentally deformed multi-phase magmas. The extent of the crystal plasticity (evidenced by electron backscatter diffraction (EBSD)) increases with increasing stress or strain, and thus remnant crystals may be used as strain markers. Thus it seems that crystal-plastic deformation plays a significant role in strain accommodation under magmatic conditions. Indeed plastic deformation of phenocrysts in conduit magmas may be an important transitional regime between ductile flow and brittle fracture, and a time-space window for such deformation is envisaged during the ascent of all highly-crystalline magmas. This phenomenon would favour strain localisation and shear zone formation at conduit margins (as the crystal-plastic deformation leads the magma toward brittle failure) and ultimately preferentially result in plug flow. During volcanic eruptions, the extrusion of high-temperature, high-viscosity magmatic plugs imposes frictional contact against conduit margins in a manner that may be considered analogous to seismogenic faults. During ascent, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite, gouge or pseudotachylyte as described in Chapter 4 at Mount St. Helens. Within volcanic systems, background temperatures are significantly higher than the geotherm permits in other upper-crustal locations, whereas confining pressures are much lower than in high-temperature, lower-crustal settings: thus via their exceptional ambient P-T conditions, volcanic systems represent unique environments for faulting. This can result in the near-equilibrium melting and slow recrystallisation of frictional melt, which hinders the development of signature pseudotachylyte characteristics. Thus frictional melting may be more common than previously thought. Indeed Chapter 5 documents a second occurrence at Soufrière Hills volcano. Here, the formation is linked to repetitive seismic “drumbeats” which occurred during both the eruption at Mount St. Helens and at Soufrière Hills. Strain localisation, brittle rupture, sliding and the formation of shear bands along the conduit margin can have important implications for the dynamics of eruptions. Specifically, the capability of degassing via the permeable porous network may be strongly influenced by the formation of pseudotachylyte, which has almost no porosity. Based on the findings in chapters 4 and 5, a series of high-velocity rotary shear (HVR) experiments were performed. In Chapter 6 the results of these experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (

Liverpool, TB (University of Bristol) Thursday 16 May 2013, 12:00-13:00

In recent years, high-resolution topographic images from Mars’ surface as well as mineralogical and chemical data, have rapidly become more accessible. Martian volcanic landforms are characterized by giant low slope shield volcanoes, abundant lava flood plains and long lava flows. In-situ rock analysis and remote sensing spectroscopy reveal mainly basaltic compositions with particularly high iron concentrations, distinct from terrestrial basalts. As yet, very little is known about the rheological properties of such iron-rich Martian magmas that are essential to understand magmatic processes. Understanding the chemical and physical contributions to lava rheology is fundamental to provide constraints on magma ascent and lava flow emplacement that shaped the volcanic landforms on Mars. This study provides an experimental investigation of the rheological properties of Martian lavas and discusses the diversity of compositions in terms of lava viscosity / flow morphology relationship. The effect of iron, and its redox state on silicate melt viscosity is experimentally investigated and the viscosities of five synthetic silicate liquids having compositions representative of the diversity of Martian volcanic rocks were measured under controlled ambient oxygen fugacity. The results highlight the low viscosity of the iron-rich Martian melts that is consistent with viscosity values derived from morphological observations. A solidified lava flow on Earth was studied by combining analyses of remote sensing images (as commonly done on Mars), as well as experimental investigations of the rheological properties of the sampled rocks, in order to describe the viscous behavior of lava as emplacement, cooling, and crystallization occur. We show that a cooling-limited basaltic flow seemingly stop flowing when it reaches a critical viscosity value that is function of crystals content and shapes. As a result, the lava apparent viscosity appears to be largely influenced by the details of the crystallization sequence and is not uniquely and simply related to the bulk chemical composition of the erupted material. Variation of the chemical evolution of Martian primary mantle melts through the volcanic history is not large to produce an significant shift of the viscosity range that could be observed them from their morphologies. Low apparent viscosities inferred from lava flow morphology on Mars may in turn be attributed to lavas with primary mantle melt composition crystallizing high proportion of olivine and possibly forming spinifex textures. Higher viscosity values derived from the morphology are compatible with mildly alkaline or trachybasalts and do not necessarily imply the occurrence of silica-rich lavas.

Liverpool, T (University of Bristol) Friday 12 April 2013, 10:00-11:00

Download Audio File The best starting point for polymer understanding is rheology, or the flow of the polymer in fluid form. What is rheology? ρηεολογψ-It's all Greek to me! Yes it is. But it doesn't need to be. The term rheology comes from the Greek word rheos, which means [...]

Download Audio File Whether you are dealing with a fluid coating or a plastic product, you need to understand rheology. Rheology of the polymer in question affects not only the final product but the settings and limitations of the process. But what is rheology? Stated simply, rheology is the [...]

This presentation discusses the equations of active hydrodynamics, the viscosity of polar systems, and the spontaneous flow of polar and non-polar systems.

Alexandre Valance, P. Richard, M. Louge and R. Delannay Friday 9 January 2009, 12.10-12.35

Takahiro Hatano (Earthquake Research Institute, University of Tokyo, Japan) Monday 5 January 2009, 15.05-15.30

We exploit the power of microrheology to measure the viscoelasticity of entangled F-actin solutions at different length scales from 1 to 100 mu m over a wide frequency range. We compare the behavior of single probe-particle motion to that of the correlated motion of two particles. By varying the average length of the filaments, we identify fluctuations that dissipate diffusively over the filament length. These provide an important relaxation mechanism of the elasticity between 0.1 and 30 rad/sec.

The stress-strain rate relationships of four silicate melt compositions (high-silica rhyolite, andesite, tholeiitic basalt, and nephelinite) have been studied using the fiber elongation method. Measurements were conducted in a stress range of 10–400 MPa and a strain rate range of 10−6 to 10−3 s−1. The stress-strain rate relationships for all the melts exhibit Newtonian behavior at low strain rates, but non-Newtonian (nonlinear stress-strain rate) behavior at higher strain rates, with strain rate increasing faster than the applied stress. The decrease in calculated shear viscosity with increasing strain rate precedes brittle failure of the fiber as the applied stress approaches the tensile strength of the melt. The decrease in viscosity observed at the high strain rates of the present study ranges from 0.25 to 2.54 log10 Pa s. The shear relaxation times τ of these melts have been estimated from the low strain rate, Newtonian, shear viscosity, using the Maxwell relationship τ = η s /G ∞. Non-Newtonian shear viscosity is observed at strain rates ( ɛ ˙ = time - 1 ) equivalent to time scales that lie 3 log10 units of time above the calculated relaxation time. Brittle failure of the fibers occurs 2 log10 units of time above the relaxation time. This study illustrates that the occurrence of non-Newtonian viscous flow in geological melts can be predicted to within a log10 unit of strain rate. High-silica rhyolite melts involved in ash flow eruptions are expected to undergo a non-Newtonian phase of deformation immediately prior to brittle failure.

The viscoelastic behavior of silicate melts has been measured for a range of compositions (NaAlSi3O8, NaCaAlSi2O7, CaMgSi2O6, Li2Si4O9, Na2Si4O9, K2Si4O9, Na2Si3O7, K2Si3O7 and Na2Si2O5) using the fiber elongation method. A1l compositions exhibit Newtonian behavior at low strain-rates, but non-Newtonian behavior at higher strain-rates, with strain-rate increasing faster than the applied stress. The decrease in shear viscosity observed at the high strain-rates ranges from 0.3 to 1.6 log10 units (Pa s). The relaxation strain-rates, relax, of these melts have been estimated from the low strain-rate, Newtonian, shear viscosity, using the Maxwell relationship; relax= –1=(s/G)–1. For all compositions investigated, the onset of non-Newtonian rheology is observed at strain-rates 2.5+0.5 orders of magnitude less than the calculated relaxation strain-rate. This difference between the non-Newtonian onset and the relaxation strain-rate is larger than that predicted by the single relaxation time Maxwell model. Normalization of the experimental strain-rates to the relaxation strain-rate predicted from the Maxwell relation, eliminates the composition. and temperature-dependence of the onset of non-Newtonian behavior. The distribution of relaxation in the viscoelastic region appears to be unrelated to melt chemistry. This conclusion is consistent with the torsional, frequency domain study of Mills (1974) which illustrated a composition-invariance of the distribution of the imaginary component of the shear modulus in melts on the Na2O-SiO2 join. The present, time domain study of viscoelasticity contrasts with frequency domain studies in terms of the absolute strains employed. The present study employs relatively large total strains (up to 2). This compares with typical strains of 10–8 in ultrasonic (frequency domain) studies. The stresses used to achieve the strain-rates required to observe viscoelastic behavior in this study approach the tensile strength of the fibers with the result that some of our experiments were terminated by fiber breakage. Although the breakage is unrelated to the observation of non-Newtonian viscosity, their close proximity in this and earlier studies suggests that brittle failure of igneous melts, may, in general, be preceded by a period of non-Newtonian rheology.

The timescale of structural relaxation in a silicate melt defines the transition from liquid (relaxed) to glassy (unrelaxed) behavior. Structural relaxation in silicate melts can be described by a relaxation time, , consistent with the observation that the timescales of both volume and shear relaxation are of the same order of magnitude. The onset of significantly unrelaxed behavior occurs 2 log10 units of time above . In the case of shear relaxation, the relaxation time can be quantified using the Maxwell relationship for a viscoelastic material; S = S/G (where S is the shear relaxation time, G is the shear modulus at infinite frequency and S is the zero frequency shear viscosity). The value of G known for SiO2 and several other silicate glasses. The shear modulus, G , and the bulk modulus, K , are similar in magnitude for every glass, with both moduli being relatively insensitive to changes in temperature and composition. In contrast, the shear viscosity of silicate melts ranges over at least ten orders of magnitude, with composition at fixed temperature, and with temperature at fixed composition. Therefore, relative to S, G may be considered a constant (independent of composition and temperature) and the value of S, the relaxation time, may be estimated directly for the large number of silicate melts for which the shear viscosity is known. For silicate melts, the relaxation times calculated from the Maxwell relationship agree well with available data for the onset of the frequency-dependence (dispersion) of acoustic velocities, the onset of non-Newtonian viscosities, the scan-rate dependence of the calorimetric glass transition, with the timescale of an oxygen diffusive jump and with the Si-O bond exchange frequency obtained from 29Si NMR studies. Using data obtained over a range of frequencies and strain-rates we illustrate the significance of relaxed versus unrelaxed behavior in laboratory experiments on silicate melts. Similarly, using strain-rate estimates for magmatic processes we evaluate the significance of the liquid-glass transition in igneous petrogenesis. Dedicated to the memory of Chris Scarfe