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spacetimewithstuartgary · 11 months

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A role for meteoritic iron in the emergence of life on Earth by Max Planck Society Researchers from the Max Planck Institute for Astronomy and Ludwig Maximilians University Munich have proposed a new scenario for the emergence of the first building blocks for life on Earth, roughly 4 billion years ago. By experiment, they showed how iron particles from meteors and from volcanic ash could have served as catalysts for converting a carbon-dioxide rich early atmosphere into hydrocarbons, but also acetaldehyde and formaldehyde, which in turn can serve as building blocks for fatty acids, nucleobases, sugars and amino acids. Their article, "Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and volcanic particles," is published in the journal Scientific Reports. To the best of our current knowledge, life on Earth emerged a mere 400 to 700 million years after the Earth itself had formed. That is a fairly quick development. For comparison, consider that afterwards, it took about 2 billion years for the first proper (eukaryotic) cells to form. The first step towards the emergence of life is the formation of organic molecules that can serve as building blocks for organisms. Given how fast life itself arose, it would be plausible for this comparatively simple first step to have been completed quickly, as well. The research described here presents a new way for such organic compounds to form on planetary scales under the conditions prevalent on the early Earth. The key supporting role goes to iron particles produced from meteorites, which act as a catalyst. Catalysts are substances whose presence speeds up specific chemical reactions, but which do not get used up in those reactions. In that way, they are akin to the tools used in manufacture: Tools are necessary to produce, say, a car, but after one car is built, the tools can be used to build the next one. From industrial chemistry to the beginnings of the Earth Key inspiration for the research came, of all things, from industrial chemistry. Specifically, Oliver Trapp, a professor at Ludwig Maximilians University, Munich, and Max Planck Fellow at the Max Planck Institute for Astronomy (MPIA), wondered whether the so-called Fischer–Tropsch process for converting carbon monoxide and hydrogen into hydrocarbons in the presence of metallic catalysts might not have had an analog on an early Earth with a carbon-dioxide-rich atmosphere. "When I looked at the chemical composition of the Campo-del-Cielo iron meteorite, consisting of iron, nickel, some cobalt and tiny amounts of iridium, I immediately realized that this is a perfect Fischer-Tropsch catalyst," explains Trapp. The logical next step was to set up an experiment to test the cosmic version of Fischer-Tropsch. Dmitry Semenov, a staff member at the Max Planck Institute for Astronomy, says, "When Oliver told me about his idea to experimentally investigate the catalytic properties of iron meteorite particles to synthesize building blocks for life, my first thought was that we should also study the catalytic properties of volcanic ash particles. After all, the early Earth should have been geologically active. There should have been plenty of fine ash particles in the atmosphere and on Earth's first land masses." Re-creating cosmic catalysis For their experiments, Trapp and Semenov teamed up with Trapp's Ph.D. student Sophia Peters, who would run the experiments as part of her Ph.D. work. For access to meteorites and minerals, as well as expertise in the analysis of such materials, they reached out to mineralogist Rupert Hochleitner, an expert on meteorites at the Mineralogische Staatssammlung in Munich. The first ingredient for the experiments was always a source of iron particles. In different versions of the experiment, those iron particles might be iron from an actual iron meteorite, or particles from an iron-containing stone meteorite, or volcanic ash from Mount Etna, the latter as a stand-in for the iron-rich particles that would be present on the early Earth with its highly active volcanism. Next, the iron particles were mixed with different minerals such as might be found on the early Earth. These minerals would act as a support structure. Catalysts are commonly found as small particles on a suitable substrate. Producing small particles Particle size matters. The fine volcanic ash particles produced by volcanic eruptions are typically a few micrometers in size. For meteorites falling through the atmosphere of the early Earth, on the other hand, atmospheric friction would ablate nanometer-size iron particles. The impact of an iron meteorite (or of the iron core of a larger asteroid) would produce micrometer-sized iron particles directly through fragmentation, and nanometer-sized particles as iron evaporated in the intense heat and later-on condensed again in the surrounding air. The researchers aimed to reproduce this variety of particle sizes in two different ways. By dissolving the meteoric material in acid, they produced nanometer-sized particles from their prepared material. And by putting either the meteoritic material or the volcanic ash into a ball mill for 15 minutes, the researchers could produce larger, micrometer-sized particles. Such a ball mill is a drum containing both the material and steel balls, which is rotated at high speeds, in this case more than ten times per second, with the steel balls grinding up the material. Since Earth's initial atmosphere did not contain oxygen, the researchers then followed up with chemical reactions that would remove almost all of the oxygen from the mixture. Producing organic molecules under pressure As the last step in each version of the experiment, the mixture was brought into a pressure chamber filled with (mostly) carbon dioxide CO2 and (some) hydrogen molecules, chosen so as to simulate the atmosphere of the early Earth. Both the exact mixture and the pressure were varied between experiments. The results were impressive: Thanks to the iron catalyst, organic compounds such as methanol, ethanol and acetaldehyde were produced, but also formaldehyde. That is an encouraging harvest—acetaldehyde and formaldehyde in particular are important building blocks for fatty acids, nucleobases (themselves the building blocks of DNA), sugars and amino acids. Importantly, these reactions took place successfully under a variety of pressure and temperature conditions. Sophia Peters says, "Since there are many different possibilities for the properties of the early Earth, I tried to experimentally test every possible scenario. In the end, I used fifty different catalysts, and ran the experiment at various values for the pressure, the temperature, and the ratio of carbon dioxide and hydrogen molecules." That the organic molecules formed under such a variety of condition is a strong indication that reactions like these could have taken place on the early Earth—whatever its precise atmospheric conditions will turn out to be. Adding a scenario to the portfolio of possible mechanisms With these results, there is now a new contender for how the first building blocks of life were formed on Earth. Joining the ranks of "classic" mechanisms such as organic synthesis near hot vents on the ocean floor, or electric discharge in a methane-rich atmosphere (as in the Urey-Miller experiment), and of models that predict how organic compounds could have formed in the depth of space and transported to Earth by asteroids or comets (see this MPIA press release), there is now another possibility: meteoric iron particles or fine volcanic ash acting as catalysts in an early, carbon-dioxide-rich atmosphere. With this spread of possibilities, learning more about the atmospheric composition and physical properties of the early Earth should allow researchers to deduce, eventually, which of the various mechanisms will give the highest yield of building blocks under the given conditions—and which thus was likely the most important mechanism for the first steps from non-life to life on our home planet. IMAGE...A small fragment of the Campo del Cielo iron meteorite. The same intense heat that partially melted the meteorite to produce the smooth surface visible here would have also evaporated and ablated iron, creating tiny, nanometer-sized particles. These particles could have acted as catalysts for producing the building blocks of life on the early Earth. Credit: O. Trapp

#space #science #Astronomy #physics #news #astrobiology

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insomniaruler · 2 years

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Hydra! Peter Parker origins because I changed my introduction format but I’m super proud of this

Peter was doomed from the day he was born to Mary and Richard Parker on the 3rd Tuesday day of June 2004. Richard and Mary hailed from the Italian neighbourhoods of New York, but they had secrets well… Mary had secrets. First she was born Siberian to Hydra Parents. She was steeped in their ideals of one day ruling the world. Her mind gained her positions in the Science wing of Shield.

Then she met Richard and she defected. She wrote letters to anyone who might listen. That Hydra was still alive and Damn it they were in the government. But life moved on for Helena “Mary” Parker (neé: Semenov). She started a cafe with Richard and then she came down pregnant. Oh her little Peter. With soft brown hair and wide brown eyes. Richard and his Brother Ben loved the little boy fiercely. And then the past came knocking.

The last thing she saw was her baby boy kicking and screaming for her in the operative’s arms. And then she passed out still screaming for her boy.

#hydra peter parker #fan fic #trope

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sandimexicola · 4 months

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a close up of a person sitting on a rock, highly detailed visionary art, inspired by tomasz alen kopera, digital visionary art, peter gric and dan mumford, psytrance artwork, hyper - detailed visionary art, beksinski and dan mumford, highly detailed dark art, anton semenov, award winning scifi art, intricate transhuman

#AI #AI art #AI art generation #AI artist #AI artwork #AI generated #AI image #AI model #AI woman #computer art #computer generated image #digital #digital art #digital drawing #digital illustration #digital painting #the amazing digital circus

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ailtrahq · 8 months

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Crypto advocacy group Coin Center has criticized the latest indictment of two former Tornado Cash developers, arguing that the facts offered don't show any clear violations of money-transmitting-related offenses.Roman Storm and Romen Semenov were indicted by the United States Office of Foreign Asset Control (OFAC) on Aug. 23 for conspiring to operate an unlicensed money-transmitting business, among other charges.In a follow-up opinion piece, Coin Center research director Peter Van Valkenburgh argues that the claims in the indictment appear to run counter to guidance from the U.S. Financial Crimes Enforcement Network — arguing that Tornado Cash only provides the software to transmit money, rather than transmitting the money itself.New Tornado Cash indictments seem to run counter to FinCEN guidanceCoin Center’s initial thoughts on a case that could potentially criminalize the publication of software codehttps://t.co/YCBv3vsZAE— Neeraj K Agrawal (@NeerajKA) August 23, 2023 "The only thing the indictment claims regarding the defendants’ unlicensed money transmission is that they 'engaged in the business of transferring funds on behalf of the public' and did so without registering with FinCEN," wrote Valkenburgh.But does the indictment state any facts that actually show that the defendants engaged in any activities that qualify as money transmission under the relevant law?He pointed to an interpretation by FinCEN as to what constitutes “money transmission services” under the U.S. Bank Secrecy Act, which states:“An anonymizing software provider is not a money transmitter.”An excerpt from FinCEN’s Virtual Currency Guidance from 2019. Source: FinCEN.Valkenburgh then referred to another excerpt stating that only people using the software can be considered money transmitters:“[A] person that utilizes the software to anonymize the person’s own transactions will be either a user or a money transmitter, depending on the purpose of each transaction.”While Valkenburgh said that Tornado Cash made it easier for individuals to use the protocol’s smart contracts to transmit money, he argued it doesn’t mean that the developers were money transmitters themselves. “[But] that doesn’t somehow mean that they became transmitters merely because they provided tools that others used to transmit their own money,” Valkenburgh explained. Valkenburgh also criticized claims in the indictment suggesting that Storm and Semenov had complete control over the protocol’s smart contracts.“Ethereum smart contracts are variable and sometimes people have no control over their operation, some control, or total control. This is the key fact needed to determine whether one is performing money transmission, he argued.Related: Crypto lobbyists still fighting to axe ‘unlawful’ Tornado Cash sanctions Coin Center first voiced its opposition toward the U.S. Treasury in October when it sued the agency for its unprecedented and unlawful sanctioning of Tornado Cash.The OFAC indictment claims Storm and Semenov ran an unlicensed money transmission service by engaging in the business of transferring funds on behalf of the public. The enforcement agency claimed the developers should have registered with FinCEN.Semenov was added to OFAC’s list of Specially Designated Nationals and Blocked Persons on Aug. 23, while Storm was arrested by the Federal Bureau of Investigation in Washington state on the same day.Alexey Pertsev, another one of Tornado Cash’s founders, was imprisoned by Dutch authorities in Aug. 2022 before being released in late April.Valkenburgh believes the outcome of the Tornado Cash saga will have a profound impact on the legal rights of United States citizens to build and publish software in the future.Magazine: Magazine: Tornado Cash 2.0 — The race to build safe and legal coin mixers Source

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bitcofun · 2 years

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Source: AdobeStock/ Vladimir Kazakov An increasing variety of crypto and personal privacy supporters are trying to combat back versus the United States Treasury's choice to prohibit the popular crypto blending service Tornado Cash Most just recently, the Electronic Frontier Foundation, a not-for-profit company safeguarding civil liberties in the digital world, has actually revealed issue relating to the Treasury's sanctions versus "an open source computer system task."" EFF is deeply worried that the U.S. Treasury Department has actually consisted of an open source computer system job, Tornado Cash, on its list of approved people," the EFF stated on Twitter. "Tornado Cash is an open source software application job and site that released a decentralized cryptocurrency mixer." The digital rights company declared that, " Code has actually long been acknowledged as speech, so there are clear First Amendment ramifications whenever the federal government hinders the publication of computer system code on a public site." The declaration by the EFF comes as GitHub, a Git repository hosting service, suspended the account of Tornado Cash designer Roman Semenov in action to the sanctions and likewise got rid of the source code for Tornado Cash. As reported, the United States Treasury's Office of Foreign Assets Control ( OFAC) has enforced sanctions on Tornado Cash on August 8 for its supposed function in cash laundering operations. Initially, some users kept in mind that this relocation would just penalize United States users while genuine wrongdoers can continue to utilize the blending service. "This brand-new legislation is just impacting Americans. It is a sanction on Americans *, however not the supposed bad stars," ETH supporter and software application engineer Adriano Feria stated a number of days earlier, including: " This was a political maneuver, managed behind closed doors, that effects specific flexibilities from law abiding Americans, and which was done without previous notification or providing clear proof of the claims." Furthermore, Coin Center, a crypto non-profit concentrated on the policy problems dealing with cryptocurrencies, has actually revealed that it is preparing a court obstacle to the restriction on Tornado Cash. Jerry Brito and Peter Van Valkenburgh, respectively Coin Center's executive director and director of research study, composed in an August 15 post that," By dealing with self-governing code as a 'individual' OFAC surpasses its statutory authority." In the short article, the duo discussed that the crypto neighborhood didn't resist when the Treasury approved crypto mixer Blender, since it "is an entity that is eventually under the control of particular people." On the other hand, the authors declared that the declaration versus Tornado Cash "does not make good sense" since "it can't be stated that Tornado Cash is an individual based on sanctions," highlighting the contradiction of calling a wise agreement a sanctionable entity. Therefore, they composed: " We plan to deal with other digital rights supporters to pursue administrative relief. We are likewise now checking out bringing an obstacle to this action in court." Meanwhile, a current report by Global Ledger, a Ukrainian start-up that assists determine the origins of Bitcoin (BTC) deals and offers banks, crypto, and fintech business with anti-money laundering (AML) compliance software application, declared that hackers are accountable for just a little portion of Tornado Cash deals. After examining 181,164 deals performed in 2 TornadoCash proxy servers, the business "had the ability to straight trace the connection in between particular cybercrime and TornadoCash in 7.73% of all these deals," Global Ledger stated in a report shown Cryptonews.com Meanwhile, as concerns surrounding Tornado Cash stack on, users continue to take out their properties from the blending service. Twister Cash's overall worth locked (TVL), which stood at over USD 460.

6 m on August 8, has actually given that plunged to USD 341.93 m, according to DeFi Llama. The increasing issues have actually likewise pressed the signatories of Tornado Cash's multisignature neighborhood fund to dissolve their positions. Peer-elected members in charge of the fund have abandoned their posts and handed control to the task's decentralized self-governing company ( DAO). Launched in 2021, the fund intended to offer rewards to forecast factors. ____ Read More

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disease · 2 years

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“RUSSIAN SILVER TUMBLER CUPS” MOSCOW | circa 1752/1757

[1] Chased with two rows of heart motifs on snakeskin ground above fluted lower section, gilt interior. [2] Chased with six rows of heart motifs on snakeskin ground, gilt interior tumbler. — 3″ diameter // 5 oz.

#u #gavrila grigoriev serebrenikov #ivan schagin #peter semenov #antique #design #drinkware #silver #hearts #moscow #18th century #russian #decorative art

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petr198 · 5 years

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In 1921, a couple of young scientists asked Kustodiev, who was writing Chaliapin at that time, to write their portrait. One was 27, the other 25. They promised the artist two things: that they would become famous and that they would generously pay for his work - they would bring a bag of flour. Clever men earned flour by repairing something at the mill. Kustodiev could not refuse a scarce product. And the heroes of the picture had to keep their word. In 1956, the Nobel Prize in chemistry will be awarded to Nikolai Semenov, pictured on the right, and in 1978, to the Nobel Prize in physics, will be Peter Kapitsa, pictured on the left. Boris Kustodiev. Portrait of Pyotr Kapitsa and Nikolai Semenov. 🔹В 1921 году к Кустодиеву, который в то время писал Шаляпина, заявилась парочка молодых ученых с просьбой написать их портрет. Одному было 27, второму 25. Они пообещали художнику две вещи: что станут знаменитыми и что щедро оплатят его работу – принесут мешок муки. Муку умники заработали, починив что-то на мельнице. Кустодиев не смог отказаться от дефицитного товара. А героям картины пришлось держать слово. В 1956-м Нобелевскую премию по химии получит изображенный справа Николай Семенов, а в 1978-м Нобелевку по физике - изображенный слева Петр Капица. Борис Кустодиев. Портрет Петра Капицы и Николая Семенова.🔹 #Nobel #Prize #chemistry #Nikolai #Semenov #pictured #NobelPrize in #physics #Peter #Kapitsa https://www.instagram.com/p/B3gF6u_Ind2/?igshid=fm23ln7ksa9e

#nobel #prize #chemistry #nikolai #semenov #pictured #nobelprize #physics #peter #kapitsa

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vinayv224 · 4 years

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Vox Sentences: 3 days of hearings and one notepad

Drew Angerer/Getty Images

Impeachment on the airwaves; Congo faces multiple deadly disease outbreaks.

Vox Sentences is your daily digest for what’s happening in the world. Sign up for the Vox Sentences newsletter, delivered straight to your inbox Monday through Friday, or view the Vox Sentences archive for past editions.

The biggest impeachment week yet

The last scheduled public impeachment hearing wrapped up Thursday. Now Democrats and Republicans are fighting about whether the evidence presented is enough to impeach President Trump. Both sides complain that partisan opposition is holding up important evidence. [NBC News / Jonathan Allen]

Here are the basics on how we got here — and what could happen next — from Vox’s big impeachment explainer. [Vox / Matthew Yglesias and Andrew Prokop]

Tuesday, Lt. Col. Alexander Vindman testified about his concern with Trump’s conduct on the call with Ukrainian President Volodymyr Zelensky. [New Yorker / John Cassidy]

On Wednesday, the biggest day of testimony, US Ambassador to the European Union Gordon Sondland said that, yes, there was a quid pro quo. [CBS News / Caroline Cournoyer, Grace Segers, and Stefan Becket]

And on Thursday, when former National Security Council Russia expert Fiona Hill and State Department official David Holmes came to answer questions, Holmes backed up Sondland’s assertion of a quid pro quo and Hill rebutted conspiracy theories about Ukraine election meddling. [Washington Post / Aaron Blake]

“I WANT NOTHING”: Trump prepared to dismiss testimony with some very strange notes. [Vox / Hannah Brown]

Here are the four arguments conservatives are using to defend Trump. [Vox / Jane Coaston]

There are also plenty of people who haven’t testified: former National Security Adviser John Bolton, the anonymous whistleblower, Secretary of State Mike Pompeo, and the president himself. [New York Times / Peter Baker]

So when’s the next step? Here are a few possibilities. [Vox / Ella Nilsen]

Thousands dead in the DRC

Children are bearing the brunt of the world’s worst current measles outbreak, which has struck the Democratic Republic of Congo. [The Guardian / Rebecca Ratcliffe]

Nearly 5,000 people have died, with about 90 percent of the deceased under the age of 5. More than 230,000 report contracting measles in the DRC, according to the World Health Organization. [IFLScience]

Health professionals are attempting to fight the disease with vaccination campaigns with limited success. That same WHO report notes that while 44 percent of the country is in the epidemic phase of the disease, many affected areas are inaccessible to medical professionals due to ongoing conflict. [Outbreak News Today]

The DRC is also suffering from an Ebola outbreak, with half the number of those perishing from measles dying from Ebola over the last 15 months. [BBC]

Miscellaneous

Trump won’t commit to the bipartisan bill to stand with Hong Kong protesters, claiming it might hurt his chances to make a trade deal with China. [CNN / Kevin Liptak and Betsy Klein]

While Russian troops have moved into Syrian domain that the US used to hold, they are facing problems they didn’t anticipate. [Al Monitor / Kirill Semenov]

Isolation rooms are a common practice in Illinois public schools. Here’s why Gov. Pritzker finds the practice “appalling,” and wants to end them. [Chicago Tribune / Jennifer Smith Richards, Jodi S. Cohen and Lakeidra Chavis]

A young man’s insurance resisted covering drug rehab near his home. Months later, he overdosed after bad treatment — thousands of miles away. Now his mother is suing the insurer. [Vox / German Lopez]

A look into how to be, and stay, resilient. [Quartz]

Verbatim

“Nowadays, you see a dead body with two shots to the chest and one in the groin. That’s how military members shoot. So you have to ask yourself, who’s teaching them to shoot or who is doing the shooting.” [US Marine Corps veteran Daniel Torres speaks on the grim fate for some deported veterans: joining drug cartels]

Watch this: How a murder changed the fate of the Amazon

How the battle for Amazon’s most valuable trees cost Chico Mendes his life. [YouTube / Ana Terra Athayde, Sam Ellis, and Christina Thornell]

“Are you sure?” Trump’s Ukraine conspiracy theory was a bit much even for Fox & Friends

How the Washington Post’s TikTok became an unofficial 2020 campaign stop

Watching The Report through Muslim eyes

Why Elsa from Frozen is a queer icon — and why Disney won’t embrace that idea

Adults are finding new (and brutal) ways to enjoy Pokémon

from Vox - All https://ift.tt/2KNBMam from Blogger https://ift.tt/37pdKwh via IFTTT

#IFTTT #Blogger

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ebenpink · 5 years

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Commentaries, Analysis, And Editorials -- March 25, 2019 https://ift.tt/2UbP0Um

Sharyl Attkisson, The Hill: Apologies to President Trump Yet, each time Trump said so, some of us in the media lampooned him. We treated any words he spoke in his own defense as if they were automatically to be disbelieved because he had uttered them. Some even declared his words to be “lies,” although they had no evidence to back up their claims. We in the media allowed unproven charges and false accusations to dominate the news landscape for more than two years, in a way that was wildly unbalanced and disproportionate to the evidence. We did a poor job of tracking down leaks of false information. We failed to reasonably weigh the motives of anonymous sources and those claiming to have secret, special evidence of Trump’s “treason.” As such, we reported a tremendous amount of false information, always to Trump’s detriment. Read more ....

Commentaries, Analysis, And Editorials -- March 25, 2019

Trump Wins Big with Mueller Report -- Daniel McCarthy, National Interest Mueller's Verdict May Be In, But Closure Is Out of Reach -- Susan Crabtree, RCP Mueller Was Trump’s Nemesis—Now He’s His Greatest Asset -- Peter Nicholas and Elaina Plott, The Atlantic The Myth that Won’t Die: Donald Trump as Russia's Puppet -- Ted Galen Carpenter, National Interest Trump's Golan recognition: A dangerous precedent? -- Chase Winter, DW Ferry disaster highlights corruption, mafia-like activities in Mosul -- Gilgamesh Nabeel, Al-Monitor Tehran Is Trouble in Cyberspace -- Peter Brookes, RCW Qatar’s break with Hamas shakes up Mideast politics -- Jack Rosen, Jerusalem Post What’s next for Kazakhstan? -- Nargis Kassenova, Asia Times There is no place like Rome for President Xi -- Gordon Watts, Asia Times Afghanistan May Not Survive a U.S. Withdrawal -- Ahmed Charai, National Interest Whose side is Russia on in Libya? -- Kirill Semenov, Al-Monitor Why Is the U.K. Jeopardising Its Five Eyes Partnership Over 5G? -- Michael Shoebridge, The Strategist Global Economy: How bad is it? -- David P. Goldman, Asia Times Antarctic mission reveals Totten Glacier secrets, along with rethink on sea level rise -- Jessica Hayes, ABC News Online from War News Updates https://ift.tt/2Tu7mM1 via IFTTT

#IFTTT #Blogger

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zeroviraluniverse-blog · 6 years

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A model for autoignition in turbulent jets -- ScienceDaily

Visit Now - http://zeroviral.com/a-model-for-autoignition-in-turbulent-jets-sciencedaily/

A model for autoignition in turbulent jets -- ScienceDaily

Jets are rapid streams of liquids or gases that forcefully shoot into a surrounding medium. When ignitable substances are involved, combustion — rapid chemical reactions that result in heat and light — can occur. Combustion in jets has many industrial and technological applications, and is thus of great interest to scientists and engineers.

The chemical interactions in jets with an oxidizing component and a chemically-reacting agent can either produce a weak reaction inducing slow oxidation in the reactive component, or develop quickly and instigate thermal runaway, which results in a swift temperature increase that spontaneously triggers combustion. Autoignition ensues when this spontaneous combustion results in a visible flame. In a paper published earlier this week in the SIAM Journal on Applied Mathematics, Peter V. Gordon, Uday G. Hegde, and Michael C. Hicks present a mathematical model for autoignition in free round turbulent jets.

The mathematics of autoignition in reactive materials dates back to the 1920s and 30s, particularly to the early work of Nikolay Semenov, David Frank-Kamenetskii, and Yakov Borisovich Zel’dovich. Their research established a mathematical combustion theory called the theory of thermal explosion, and subsequent studies were typically based on their findings. One common truth characteristically unites all thermal explosion studies: prior to autoignition, the reactive systems’ dynamics are fairly straightforward. As a result, scientists can simplify a system of equations governing the evolution of reactive systems to create and examine models of autoignition in great detail.

Gordon et al. use recent experimental advances in the study of hydrothermal flames to analyze autoignition in free jets. First observed about 30 years ago, hydrothermal flames arise in aqueous (water) environments at conditions above the thermodynamical critical point of water. They are a key component of an emerging “green” water purification technology called supercritical water oxidation (SCWO), and occur spontaneously during SCWO via autoignition. “The principal advantage of this technology is that it allows almost perfect conversion rates of organically-contaminated waste streams without producing harmful intermediate species,” Hicks said. “The presence of hydrothermal flames in SCWO devices is often desirable since it allows for substantially-reduced reaction times — from seconds to milliseconds — thereby dramatically enhancing decomposition rates.”

Experimental studies of hydrothermal flames typically involve a closed combustion vessel with an injection inlet. The authors derive an elementary autoignition model for a fully-developed, round turbulent reactive jet. The jet is formed via injection of fuel and oxidizer into the vessel, which contains pure water at a supercritical state at rest. The injected stream creates a round jet that is either laminar (smooth with parallel flow) or turbulent (irregular). When conditions are right, the jet autoignites axially downstream from the injection point.

To effectively illustrate autoignition, Gordon et al. make certain assumptions about the jet’s form and overall conditions. “The key experimental facts that we use in our theory is that the shape of the jet, as well as the velocity and concentration fields of the species within the jet prior to autoignition, can be viewed as a priori prescribed,” Gordon said. “Specifically, in a first approximation, the main region of the jet assumes the shape of a conical frustum (a cone with the pointed top sliced off). Moreover, the velocity within the main part of the jet — in the direction perpendicular to the jet — is negligible in comparison to one in the direction of injection. The latter is radially symmetric and inversely proportional to the distance from the injection point, and the same applies to concentration fields of reactive and oxidizing components within the jet.”

Using experimental observations and the aforementioned assumptions, the authors separate the model’s hydrodynamic and reactive components. This drastically simplifies autoignition, reducing it to one differential equation. “The problem reduces to the analysis of a single equation that describes evolution of the temperature field within the jet, which we can analyze using a general framework of the Frank-Kamenetskii theory of thermal explosion,” Gordon said. “This leads to sharp characterization of an autoignition event in terms of principal physicochemical and geometric parameters.”

Gordon et al.’s model is a counterpart to their previous model of autoignition for laminar co-flow jets, and reveals some valuable truths about autoignition. “The results of the model’s analysis allow us to correlate specific values of principal physicochemical and geometric parameters of the problem with the event of autoignition, or absence thereof,” Hegde said. “This, in turn, allows one to identify parametric regimes where autoignition takes place, and therefore can be used in guiding experimental studies of hydrothermal flames.”

The authors’ conclusions will serve the experimental studies of scientists exploring the relation between hydrothermal flames and autoignition. “This work is applicable in the design of next-generation SCWO reactors that will rely on the spontaneous ignition and subsequent control of hydrothermal flames to sustain temperatures and reaction kinetics of SCWO processes in real world applications, like waste remediation and water reclamation,” Hicks said. Such research is transpiring at NASA’s Glenn Research Center, in Cleveland, Ohio.

“We are currently conducting laboratory experiments with hydrothermal flames in organically-contaminated environments to verify the model predictions,” Hegde said. “Qualitatively, we have already seen good agreement with predicted model trends. Quantitative comparisons are more challenging due to the technical difficulties of making accurate in situ measurements in SCWO environments, and are the subject of ongoing and future work.”

#autoignition #jets #Model #ScienceDaily #turbulent #Facts

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demonstrous · 7 years

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Adobe - Photoshop 25th Anniversary – "Dream On" from Brady Baltezore on Vimeo.

Celebrating 25 years of Adobe Photoshop

Client: Adobe Project: Photoshop 25th Anniversary – "Dream On" Length: 60 seconds Product: Adobe Photoshop Agency: Goodby, Silverstein & Partners Co-Chairman, Creative Director: Rich Silverstein Creative Directors: Adam Reeves, Patrick Knowlton, Will Elliott Associate Creative Directors: Sam Luchini, Roger Baran Executive Producer: Tod Puckett Producer: Timothy Plain Director of Graphic Services: Jim King Business Affairs Manager: Heidi Killeen Account Director: Joel Giullian Account Managers: Cassi Norman, Chelsea Bruzzone Brand Strategy Director: Anne Faricy Director of Communications Strategy: Christine Chen Senior Communications Strategist: Joe Gruchacz Communications Strategist: Victoria Barbatelli Junior Communications Strategist: Tara Hughes Production and Postproduction Directors: Brady Baltezore, Mike Landry Editorial Company: Rock Paper Scissors Executive Producer: Angela Dorian Producer: Cristina Matracia Editor: Grant Surmi Assistant Editor: Arielle Zakowski Color: Chris Martin @ Spy Post Graphics Company: eLevel Studios Executive Producer: PJ Koll Creative Directors: Brady Baltezore, Mike Landry Producer: Luke Dillon Artists: Nathan Shipley, Kyle Westbrook, Chad Ford, Jessica Gibson, Karim Fawzy, Jon Corriveau, Devin Earthman Final Mix: Dave Baker Photoshop Effects Artists: Sam Nordemann, Kleber Lacher, Philip Chudy Artwork Collaborators: Adhemas Batista Ahmed Emad Eldin Alex Trouchut Alexey Romanowsky Anka Zhuravleva Anthony Hearsey Anton Semenov Artur Szygulski Bill Mayer Brian Miller Chris Slabber Claude Shade Clifton Harvey Cristian Girotto Damián Domínguez Dan Elijah Fajardo David Fuhrer David Mascha David McLeod Edit Ballai El Grand Chamaco Emi Haze Evgeny Kazantsev Fabian Flenker Fede Cook Flora Borsi Foreal Gerrel Saunders Henrique Cassab Jakob Wagner James Roper Jason Seiler Jerico Santander Jimmy Williams jonathan ball Jordan Metcalf José Bernabé Juan Carlos Paz -Bakea k2man* Kittozutto KJA Artists Fredrico Kristina Varaksina La Boca Leandro Senna Lucas Zimmermann Luke Choice Mario Sanchez Nevado Mart Biemans Martin Grohs Maxim Vasilyev Mike Campau Oleg Dou Paolo Todde Pawel Nolbert Peter Stylianou Richard Perez Rik Oostenbroek Romain Laurent Rubén Álvarez Ruslan Khasanov Sasha Vinogradova Stu Ballinger Tejal Patni ThisisMessor Thomas Koch Thomas Muller Tim Tadder Vault 49 Vincent Viriot Zaki Abdelmounim Zooka

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t-baba · 7 years

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