Invited contributions from early career researchers 2020 at Physics of Fluids.

Patrick Comiskey and Christopher Staszel are mentioned in a special issue of Physics of Fluids which is dedicated to outstanding
young scientists who are at the early stages of their “scientific life.”

 

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Solving a murder case with physics

Blood

In 2009, famed music producer Phil Spector was found guilty of the murder of actress Lana Clarkson, who was found dead from a single gunshot to her mouth at close range in Spector’s California mansion.

During the trial, the attorney argued that Spector couldn’t have been the shooter because his white dinner jacket only had a handful blood droplets on it. If he shot Clarkson, the jacket would be covered with blood.

After watching a film about the trial, UIC Distinguished Professor Alexander Yarin was intrigued by the scientific questions it raised. Yarin and his colleagues from Iowa State University—Assistant Professor James Michael and Associate Professor Daniel Attinger— started researching blood spatter, and their recent papers show how Spector could be the shooter and remain relatively free of blood droplets.

“We did simulations with my PhD student Gen Li and found that there are scenarios where droplets can be turned around completely and land behind the victim. Experiments of Dr. Michael confirmed that prediction.”

In addition, the researchers noted that a shooter could stand in a certain position or at a specific angle and all backward blood spatter would be turned around, keeping the shooter clean.

“Essentially, I believe this proves that a shooter could have been guilty. There is an explanation for how his outfit could have been basically clean. And the explanation is essentially physically sound,” Yarin said.

The researchers plan to continue investigating the blood spatter as they examine a variety of interesting situations and variables.

“We want to go much further,” he said. “You have the effect of skin, which may not be that significant, but the effect of surrounding bones can be very significant,” he said. A cranial wound, Yarin noted as an example, does not result in an immediate spatter; it is delayed.

“There’s a lot of interest in the phenomena associated with these types of wounds,” Yarin said. “We would like to study them and understand them better because there might be several waves of gushes of blood and brain matter from such wounds.”

Those results have been published on Physics of Fluids as Featured Article, read more with following link:

Li, G., Sliefert, N., Michael, J. B., & Yarin, A. L. (2021). Blood backspatter interaction with propellant gases. Physics of Fluids, 33(4), 043318. 

Sliefert, N., Li, G., Michael, J. B., & Yarin, A. L. (2021). Experimental and numerical study of blood backspatter interaction with firearm propellant gases. Physics of Fluids, 33(4), 043319.

 

Forensics puzzle cracked via fluid mechanical principles

Blood trajectory

In Physics of Fluids, from AIP Publishing, the researchers present theoretical results revealing an interaction of the incoming vortex ring of propellant muzzle gases with backward blood spatter.

A detailed analytical theory of such turbulent self-similar vortex rings was given by this group in earlier work and is linked mathematically to the theory of quantum oscillators.

“In our previous work, we determined the physical mechanism of backward spatter as an inevitable instability triggered by acceleration of a denser fluid, blood, toward a lighter fluid, air,” said Alexander Yarin, a distinguished professor at the University of Illinois at Chicago. “This is the so-called Rayleigh-Taylor instability, which is responsible for water dripping from a ceiling.”

Backward spatter droplets fly from the victim toward the shooter after being splashed by a penetrating bullet. So the researchers zeroed in on how these blood droplets interact with a turbulent vortex ring of muzzle gases moving from the shooter toward the victim.

They predict that backward blood spatter droplets can be entrained — incorporated and swept along within its flow — by the approaching turbulent vortex ring, even being turned around.

“This means that such droplets can even land behind the victim, along with the forward splatter being caused by a penetrated bullet,” said Yarin. “With a certain position of the shooter relative to the victim, it is possible for the shooter’s clothing to remain practically free of bloodstains.”

Who pulled the trigger? Gun muzzle exhaust may complicate analysis of crime scenes

Interaction with blood backspatter

When a gun is fired, the gases that propel the bullet forward also issue forth from the barrel at high speed, forming turbulent vortex rings. As blood droplets coming from the victim encounter a vortex going in the opposite direction, they can get swept aside or along by the gas flow. They may even end up completely reversing direction, Yarin and colleagues report today in Physics of Fluids.

Can dental scalers, drills be used without spraying aerosols?

Adding a polymer to a dental office’s water system can completely eliminate aerosols generated by ultrasonic scalers and drills, reducing the transmission risk of pathogens such as SARS-CoV-2, according to a study published online August 25 in Physics of Fluids.

Adding polyacrylic acid to a dental office’s irrigation system changes the way water responds; the water and polymer solution forms strands that remain near the tips of dental tools, preventing droplets from entering the air, according to the authors.

 

Reopening dentistry after COVID-19: Complete suppression of aerosolization in dental procedures by viscoelastic Medusa Gorgo Reported in German

German

Physiker der Universität Illinois Chicago verfolgen einen ganz neuen Ansatz, um die Gefahr einer möglichen Infektion mit SARS-CoV-2 bei einer zahnärztlichen Behandlung zu reduzieren: Sie wollen die Spraynebelbildung komplett verhindern.

Reopening Dentistry With Complete Aerosol Suppression

12

Ever since the onset of the COVID-19 pandemic, the potential for transmission of virus particles through aerosol generation has had a significant impact on the delivery of dental procedures and created a heightened risk for the dental team.

For months, it seemed the problem of aerosol production in dental offices was insurmountable. That is until a team of researchers, led by Dr. Alexander Yarin, Professor at the Department of Mechanical and Industrial Engineering at the University of Illinois at Chicago, came up with a novel approach that alters the physical response of water to the rotary and ultrasonic forces that are used in dentistry.

In this breakthrough discussion with Chiraz Guessaier, Manager of CDA Oasis, Dr. Yarin presents his ground-breaking findings that may eliminate the risks posed by aerosol generation entirely. He explains the concept of risk elasticity and walks through clear video evidence of aerosol suppression. He also suggests it may not be long before this breakthrough technology finds its way into dental offices all over the world.

Polymers in water at dentist can prevent aerosol mists that spread germs

1

Researchers say the addition of food-grade polymers to water solutions, such as polyacrylic acid, can prevent misting.

In lab experiments, small amounts of polyacrylic acid eliminated aerosolization entirely, they say.

“It was amazing that these materials were capable of so easily and completely suppressing aerosolization by dental tools, with significant inertial forces involved. Nevertheless, the elastic forces generated by small polymer additives were stronger,” said Yarin, a professor of mechanical and industrial engineering at the University of Illinois.

Food-additive might make pandemic dental visits safer

covid_19

Scientists may have a solution to a hazard faced by dentists and their patients during the coronavirus pandemic. The mists generated by water used in dentists’ tools could potentially carry exhaled coronavirus particles through the air. Mixing the water with a small amount of an FDA-approved food additive called polyacrylic acid can markedly suppress these mists or even prevent them, researchers reported on Tuesday in the journal Physics of Fluid. “What was surprising is that the very first experiment in my lab completely proved the concept,” coauthor Alexander Yarin of the University of Illinois at Chicago said in a news release. “It was amazing that these materials were capable of so easily and completely suppressing aerosolization by dental tools.” The spraying mist results when water encounters rapid vibration of a dental tool or the centrifugal force of a drill, which bursts water into tiny droplets and propels them into the air, the researchers explain. The polymer suppresses these bursts as large polymer molecules stretch like rubber bands, pulling the droplets back and preventing them from becoming airborne.

Polymers Prevent Potentially Hazardous Mist During Dentist Visit

pas

Researchers at the University of Illinois at Chicago couldn’t stop thinking about the spinning, vibrating tools in a dentist’s office that turn water into mist and send it flying into the air. If that mist contains a virus or some other pathogen, it is a health hazard for dentists and patients.

 

In a paper published this week in Physics of Fluids, by AIP Publishing, Alexander Yarin and his colleagues discovered that the forces of a vibrating tool or dentist’s drill are no match for the viscoelastic properties of food-grade polymers, such as polyacrylic acid, which they used as a small admixture to water in dental settings.

Engineering breakthrough can mitigate COVID-19 contamination in dental clinics

Dental

Dental practices have been shuttered since March after being cautioned by the American Dental Association and the Centers for Disease Control and Prevention to close their offices to all but emergencies. Recently, they provided a framework for reopening facilities, which calls for offices to carry extra personal protective equipment (PPE) like face masks, shields, eye protection, gowns and gloves, and to change them frequently. The guidelines call for the complete cleaning of workspaces between patients and a pause to allow air filtration systems to remove potentially infectious particles.

UIC’s College of Dentistry is following the guidelines to protect patients, faculty, staff and students against COVID-19. However, these measures do not guarantee complete protection against the inhalation of aerosols generated by some of the essential tools used by dentists.

To mitigate the aerosols, the dental school leaders reached out to experts at the UIC College of Engineering to help them solve the problem.

UIC’s engineering team, made up of faculty and students from Mechanical and Industrial engineering (MIE) and Electrical and Computer Engineering (ECE), are studying how aerosols are dispersed from dental instruments.

With the polymer solution, threads and filaments do not break up and droplets do not detach, as demonstrated in the lab experiments and in the dental clinic. Yarin and his PhD students tested the solutions at low speeds and at the highest speed of the dental drill and all Cavitron powers, which provided the same suppression of droplet formation.

PhD students Yasmin Dias, Jevon Plog and Jingwei Wu worked under the direction of Yarin on this research. “These three students were very instrumental and heroically came to UIC when everything was closed, and we worked alone there for quite some time,” Yarin said.

UIC is now filing a patent for this new technology and working with companies to get the process implemented, which will allow dental schools and clinics to reopen and operate safely. Their research will be published as a feature article in the journal Physics of Fluids under the title “Reopening Dentistry after COVID-19: Complete Suppression of Aerosolization in Dental Procedures by Viscoelastic Medusa Gorgo.”

Professor Yarin uses plants to research fighting forest fires

fire

Forest fires cause tremendous trouble as they threaten lives, homes, communities, and destroy millions of acres of land annually, leaving billions of dollars of damage in their wake.

While firefighters use a wide range of tactics to combat the fires, recent research conducted by UIC Distinguished Professor Alexander Yarin and his team in the Multiscale Mechanics and Nanotechnology Laboratory at UIC shows how some plants can help to understand the intrinsic mechanism of forest fires. Professor Eyal Zussman, of the Technion – Israel Institute of Technology, and PhD student Wenshuo Zhang collaborated on the research.

The results of their research were published in the journal Experimental Thermal and Fluid Science under the title “Heat and mass transfer resulting in eruptive jetting from stems and leaves during distillation stage of forest fire.”

Researchers are revolutionizing battery industry with novel approach to produce solid ceramic batteries

solution blowing

Approximately 17 million cars and light trucks were purchased in 2019, and all of those vehicles have batteries. Every battery takes time to manufacture and a new technique may make batteries safer, while reducing costs and processing time.

Professors Reza Shahbazian-Yassar and Alexander Yarin, both of the Mechanical and Industrial Engineering  Department at the University of Illinois Chicago, and their students recently had a research paper titled “Solution Blowing Synthesis of Li-Conductive Ceramic Nanofibers” in the journal ACS Applied Materials and Interfaces.

IIT-Mandi develops high-efficiency face masks from waste plastic bottles

IIT

IIT’s School of Engineering assistant professor Dr Sumit Sinha Ray, along with research scholars Ashish Kakoria and Sheshang Singh Chandel, used waste plastic bottles to develop a single thin layer of nano-nonwoven membrane that provides desirable particle filtration efficiency at par with N95 respirator and a medical mask.

“The nono-fibres can do wonders for face masks. Air-borne particulate and pollutant removal efficiency and breathability are two main criteria for an
efficient face mask. The commercially available melt blown fabric-based masks can be efficient at a cost of high-breathing resistance, while generic 3-ply surgical masks are breathable but have meagre efficiency. But, nano-fibresbased masks can filter out small particles efficiently despite being comfortably breathable,” Dr Sumit Sinha Ray said.

Calling the shots

Calling the shots

Blood spatter can provide a lot of information to an investigator at a crime scene. Unfortunately, current methods do not tell the whole story. UIC Distinguished Professor Alexander Yarin and his colleagues have shown that investigators can gather more accurate information. Their blood spatter research has the potential to change crime scene investigations in the same way DNA changed other police investigations.

Yarin and his associates made a splash in the science and law enforcement communities with their research on blood spatter with their papers, Prediction of Blood Backspatter from a Gunshot in Bloodstain Pattern Analysis, which was published in the journal Physical Review Fluids in 2016, High-Speed Video Analysis of Forward and Backward Spattered Blood Droplets published in Forensic Science International in 2017, and Hydrodynamics of back spatter by blunt bullet gunshot with a link to bloodstain pattern analysis, published in Physical Review Fluids in 2017.

Flying high

Flying high

Suman Sinha Ray, a postdoctoral fellow and recent UIC graduate, and his brother, Sumit Sinha Ray, a graduate student, conducted experiments in 2013 in a Novespace & European Space Agency plane while floating weightless. Under the direction of Alexander Yarin, UIC professor of mechanical and industrial engineering, the brothers went aloft and braved high- and zero-gravity to test a cooling system Yarin’s team developed for hot-running microelectronics.
Satellites, rockets, and drones have elaborate electro-optical and infrared sensors, recording equipment, and data processing systems that generate heat and can burn out. Yarin and his group have developed novel nano-textured surfaces that dramatically increase cooling efficiency. They were interested in learning how well the evaporative cooling system they developed would work under conditions of twice-normal or zero gravity. The three flights were physically demanding but “exciting and fun,” said Suman, who worked on the computer running the experiment. Sumit photographed the action and monitored the pressurized rigging running the system.The research was sponsored by NASA and in collaboration with a Germanuniversity.