Genes affect when trees sprout leaves in the spring. Understanding how these genes work could help scientists adapt trees to be more resilient to climate change.

One of the surest signs of spring is how the vibrantly lime-green tinge trees develop as their buds open and tiny new leaves unfurl. Bud-break is the scientific name for this process — a straightforward term for the grand genetic mechanism that allows trees to leaf out and do their summer work of photosynthesis to store up energy for the coming winter.

Bud-break is precluded by bud-set, which occurs in the autumn. After trees drop their leaves and as the days shorten and grow colder, new buds grow on branches. Like many wildflowers, trees require a period of dormancy at colder temperatures — a process fine-tuned by evolution — before bud-break can occur.

But as the changing climate becomes increasingly unpredictable, late frosts are more common — and many trees initiate bud-break too early or too late. For farmers who grow fruit- and nut-bearing trees as well as grape vines, a mistimed bud-break and a frost could mean the difference between a good harvest and none at all.

For example, a late frost in 2007 across the eastern United States. resulted in an estimated agricultural loss of $112 million, including $86 million in losses to fruit crops. Poorly synchronized bud-break can also lead to pest and disease outbreaks.

Understanding bud-break genetics enables scientists to modify or select crop varieties more resilient to such threats.

Victor Busov, professor in the College of Forest Resources and Environmental Science at Michigan Technological University, along with colleagues in the U.S. and Sweden, published new research about the transcription factors responsible for early bud-break in the journal Nature Communications. Transcription factors are genes that regulate other genes by binding to DNA and giving activation instructions.

Regulating Bud-break

The properties of transcription factors help scientists determine what other genes might be involved in a particular process like starting bud-break.

Busov and collaborators previously identified transcription factors for early bud-break 1 (EBB1) and short vegetative phase-like (SVL), which directly interact to control bud-break. The research team has now identified and characterized the early bud-break 3 (EBB3) gene. EBB3 is a temperature-responsive regulator of bud-break controlled by interactions between genes and the surrounding environment. The transcription factor provides a direct link to activation of the cell cycle during bud-break.

“We know now EBB3 is providing a direct link through the signaling pathway for how these cells divide,” Busov said. “Once we found the third gene, we started to put them together in a coherent pathway, which helps us see the bigger picture.”

Using poplar and flowering locust trees in the Michigan Tech greenhouses, the researchers mimicked the daylight length and temperature of an average summer day for a period of time, followed by a period that mimicked average winter days. Then, the scientists conducted gene expression analysis to determine how the transcription factors worked together to help the trees judge when to put forth leaves in the greenhouse’s artificial springtime.

Busov said the analysis reveals how particular genes activate through the season or in response to specific environmental factors.

“We need to understand not only three transcription factors, but the whole network,” Busov said. “Once we identify the genes, we do experiments where we dial up or down the expression of the gene. We look at what the effect of these actions is on offspring. Identifying variation in the network will allow us to regulate early bud-break. New technologies of sequencing are empowering these areas.”

Speaking for the Trees

The climate has profound effects on the genetic processes that regulate bud-break. The first of these effects is warming winters. In places that no longer experience enough cold, trees do not get the necessary growth-resetting cold exposure. Cold exposure is crucial for strong and uniform bloom and leaf-out, which is needed to produce a good crop, whether it’s peaches, apples, cherries, grapes or almonds.

The second way climate change affects trees is late frosts. Bud-break is all about timing; trees shouldn’t initiate leaf growth until the danger of frost is past. Instances of extremely late frost are becoming more common, and as Busov notes, research indicates that the frequency of these events is increased by climate change.

“Late frost has detrimental effects, not only on fruit trees, resulting in crop loss, but also forest trees,” Busov said. “Frost negatively affects growth and inflicts injuries to growing organs, making trees susceptible to disease and pests.”

To make matters worse, trees are such long-lived organisms that their evolution is not keeping pace with the rate at which the climate is changing.

“For trees, their adaption is generational – but their generations are so long, their adaptation is also so long,” Busov said. “You need some way to speed this up, both in fruit trees and in forest populations. With rapid changes, there is no time for this adaptation.”

Devising new approaches for accelerated tree adaptation to climate change can ensure bud-break happens at precisely the right time each spring. Using their understanding of the genetic pathways that control bud-break, scientists hope to genetically modify crops to adapt to warmer winters and unpredictable frosts. Scientists can also conduct genome-assisted breeding — the age-old process of natural selection, with science-enabled knowledge.

Value estimations for grid-tied photovoltaic systems prove solar panels are beneficial for utility companies and consumers alike.

Beyond the environmental benefits and lower electric bills, it turns out installing solar panels on your house actually benefits your whole community.

For years some utility companies have worried that solar panels drive up electric costs for people without panels. Joshua Pearce, Richard Witte Endowed Professor of Materials Science and Engineering and professor of electrical and computer engineering at Michigan Technological University, has shown the opposite is true — grid-tied solar photovoltaic (PV) owners are actually subsidizing their non-PV neighbors.

Most PV systems are grid-tied and convert sunlight directly into electricity that is either used on-site or fed back into the grid. At night or on cloudy days, PV-owning customers use grid-sourced electricity so no batteries are needed.  

“Anyone who puts up solar is being a great citizen for their neighbors and for their local utility,” Pearce said, noting that when someone puts up grid-tied solar panels, they are essentially investing in the grid itself. “Customers with solar distributed generation are making it so utility companies don’t have to make as many infrastructure investments, while at the same time solar shaves down peak demands when electricity is the most expensive.”

Pearce and Koami Soulemane Hayibo, graduate student in the Michigan Tech Open Sustainability Technology (MOST) Lab, found that grid-tied PV-owning utility customers are undercompensated in most of the U.S., as the “value of solar” eclipses both the net metering and two-tiered rates that utilities pay for solar electricity. Their results are published online now and will be printed in the March issue of Renewable and Sustainable Energy Reviews.

Value of Solar

The value of solar is becoming the preferred method for evaluating the economics of grid-tied PV systems. Yet value of solar calculations are challenging and there is widespread disagreement in the literature on the methods and data needed. To overcome these limitations, Pearce and Hayibo’s paper reviews past studies to develop a generalized model that considers realistic costs and liabilities utility companies can avoid when individual people install grid-tied solar panels. Each component of the value has a sensitivity analysis run on the core variables and these sensitivities are applied for the total value of solar.

The overall value of solar equation has numerous components:

• Avoided operation and maintenance costs (fixed and variable)
• Avoided fuel.
• Avoided generations capacity.
• Avoided reserve capacity (plants on standby that turn on if you have, for example, a large air conditioning load on hot day).
• Avoided transmission capacity (lines).
• Environmental and health liability costs associated with forms of electric generation that are polluting.

Pearce said one of the paper’s goals was to provide the equations to determine the value of solar so individual utility companies can plug in their proprietary data to quickly make a complete valuation.

“It can be concluded that substantial future regulatory reform is needed to ensure that grid-tied solar PV owners are not unjustly subsidizing U.S. electric utilities,” Pearce explains. “This study provides greater clarity to decision makers so they see solar PV is truly an economic benefit in the best interest of all utility customers.”

Not Just Solar Panels

In addition to being good for human communities, solar PV technology is good for the planet, and it is now a profitable method to decarbonize the grid. If catastrophic climate change is to be avoided, emissions from transportation and heating must also decarbonize, Pearce argues.

One approach to renewable heating is leveraging improvements in PV with heat pumps (HPs), and it turns out investing in PV+HP tech has a better rate of return than CDs or savings accounts.

To determine the potential for PV+HP systems in Michigan’s Upper Peninsula, Pearce performed numerical simulations and economic analysis using the same loads and climate, but with local electricity and natural gas rates for Sault Ste. Marie, in both Canada and U.S. North American residents can profitably install residential PV+HP systems, earning up to 1.9% return in the U.S. and 2.7% in Canada, to provide for all of their electric and heating needs. 

“Our results suggest northern homeowners have a clear and simple method to reduce their greenhouse gas emissions by making an investment that offers a higher internal rate of return than savings accounts, CDs and global investment certificates in both the U.S. and Canada,” Pearce said. “Residential PV and solar-powered heat pumps can be considered 25-year investments in financial security and environmental sustainability.”

Sixteen years of remote sensing data reveals that in Earth’s largest freshwater lakes, climate change influences carbon fixation trends.

NASA-funded research on the 11 largest freshwater lakes in the world coupled field and satellite observations to provide a new understanding of how large bodies of water fix carbon, as well as how a changing climate and lakes interact.

Scientists at the Michigan Tech Research Institute (MTRI) studied the five Laurentian Great Lakes bordering the U.S. and Canada; the three African Great Lakes, Tanganyika, Victoria and Malawi; Lake Baikal in Russia; and Great Bear and Great Slave lakes in Canada.

These 11 lakes hold more than 50% of the surface freshwater that millions of people and countless other creatures rely on, underscoring the importance of understanding how they are being altered by climate change and other factors.

The two Canadian lakes and Lake Tanganyika saw the greatest changes in primary productivity — the growth of algae in a water body. Productivity fluctuations point to big changes in lake ecosystems.

“The base of the food chain in these lakes is algal productivity. These lakes are oceanic in size, and are teaming with phytoplankton — small algae,” said co-author Gary Fahnenstiel, a fellow at MTRI and recently retired senior research scientist for NOAA’s Great Lakes Environmental Research Laboratory. “We measured the carbon fixation rate, which is the rate at which the algae photosynthesize in these lakes. As that rate changes, whether increasing or decreasing, it means the whole lake is changing, which has ramifications all the way up the food chain, from the zooplankton to the fish.”

Many factors affect these lakes. Climate change, increasing nutrients (eutrophication) and invasive species all combine to cause systemwide change — making it difficult to pinpoint specific causes, particularly from the ground with limited on-site observations.

Counting Phytoplankton with Color

But satellite imagery has made sorting through the noise easier and provides insights over time and space. Michael Sayers, MTRI research scientist and study lead author, uses ocean color remote sensing — making inferences about type and quantity of phytoplankton based on the color of the water — to track freshwater phytoplankton dynamics.

“We’ve relied on NASA assets — the MODIS satellite, which has been flying since 2002, to which we apply the algorithm and model we’ve been developing at MTRI for a decade,” Sayers said. “When we start to tally the numbers of pixels as observations globally for 11 lakes for 16 years, it is really quite remarkable.” The pixels observed per lake number “in the millions,” he added.

One of the most remarkable aspects of the results is just how fast changes in these freshwater lakes have occurred — a noticeable amount in fewer than 20 years. The research contributes to NASA’s Carbon Monitoring System’s goal of determining how much freshwater lakes contribute to the global carbon cycle.

“Three of the largest lakes in the world are showing major changes related to climate change, with a 20-25% change in overall biological productivity in just the past 16 years,” Fahnenstiel said.

More Than Algae

In the 16 years of data, Great Bear and Great Slave lakes in northern Canada saw the greatest increases in productivity, while Lake Tanganyika in southeastern Africa has seen decreases. The trends are linked to increases in water temperatures, as well as solar radiation and a reduction in wind speed.

Sayers said looking at productivity, algal abundance, water clarity, water temperature, solar radiation and wind speeds at freshwater lakes provides a richer picture of the overall ecosystem.

“Temperature and solar radiation are factors of climate change,” Sayers said. “Chlorophyll and water transparency changes are not necessarily caused by climate change, but could be caused by eutrophication or invasive species, like quagga mussels.”

The researchers used lake measurements performed by the Great Lakes Research Center research vessel fleet to ground truth the satellite observations and to provide input for model estimates.

The article “Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018” is published in the journal Water. The researchers plan to continue their research, applying what they’ve learned so far to the role harmful algal blooms have on carbon flux to the atmosphere.

As the saying goes, water is life. Gaining a better understanding of how lake productivity changes affect the bodies of water so many people rely on is important to the communities who live on the lakeshores. It’s also significant to the global community as we delve deeper into the role freshwater lakes play in the global carbon cycle and climate change.

Michigan Technological University is a public research university, home to more than 7,000 students from 54 countries. Founded in 1885, the University offers more than 120 undergraduate and graduate degree programs in science and technology, engineering, forestry, business and economics, health professions, humanities, mathematics, and social sciences. Our campus in Michigan’s Upper Peninsula overlooks the Keweenaw Waterway and is just a few miles from Lake Superior.

Half of vaccines are wasted annually because they aren’t kept cold. Chemical engineers have discovered a way to stabilize viruses in vaccines with proteins instead of temperature.

Ever receive a vaccination that seemed to burn while it was injected? The vaccine solution likely contained a lot of salt or sugar — natural preservatives that help keep it stable, in addition to the cold temperature at which it was kept.

The viruses in vaccines, which train our cells to identify and vanquish viral invaders, must be kept cold to keep them from bursting apart. The typical shipping temperature for vaccines ranges from 2 to 8 degrees Celsius (35 to 47 degrees Fahrenheit).

Viruses are kept cold for the same reason we refrigerate food items. “You wouldn’t take a steak and leave it out on your counter for any length of time and then eat it,” said Caryn Heldt, director of the Health Research Institute at Michigan Technological University and professor of chemical engineering. “A steak has the same stability issues — it has proteins, fats, and other molecules that, in order to keep them stable, we need to keep them cold.”

Like proteins, viruses unfold when it’s hot or there’s space to move around. Heat provides energy for viruses to shake themselves apart, and not being crowded gives them the room to fall apart. Stable vaccines need cold or crowding.

But what if cold storage isn’t available? What if someone accidentally leaves the package on the counter? What if the power goes out? 

Heldt, together with Sarah Perry, professor of chemical engineering at the University of Massachusetts Amherst, has developed a way to mimic the body’s environment in vaccines using a process called complex coacervation. Rather than relying on refrigeration, Perry and Heldt tap the other method to keep viruses stable — crowding.

Freezer Camp

To keep the viruses in vaccines stable, everyone along the supply chain, from manufacturing facility to shipping company to doctor’s office, must maintain the cold temperature. This cooperative effort is known as the cold chain. If a vaccine is kept above that temperature range for even an hour, it may become ruined and unusable.

The World Health Organization estimates that up to 50% of vaccines are wasted every year because the cold chain and ideal temperature for storage cannot be maintained.

The human body is a crowded place. Cells of varying shapes and sizes jockey for position. This includes viruses, which do their nefarious work by hostile takeover. Viruses invade our cells, commandeering them to replicate. Unchecked, virus copies explode out of the cells like darts through a balloon. Then all of those replicas go and do the same to other cells — and before you know it, you’re sick.

Heldt researches vaccine manufacturing techniques and the COVID-19 pandemic has served as a masterclass. But SARS-CoV-2 isn’t the only virus in the world — there is still need for other vaccines and storage methods that don’t rely on refrigeration.

“The conditions for a vaccine that make it good to be injected into someone’s body are almost the opposite of what makes a virus stable,” Heldt said. “There’s a really hard trade-off of keeping the virus stable to get good immune response, while having the right components in the vaccine that are safe to inject.”

Virus Burritos

The process of complex coacervation keeps viruses in vaccine solutions stable by crowding them tightly together, reducing the need for refrigeration. Graphic Credit: Caryn Heldt and Sarah Perry

Heldt and Perry use polypeptides — synthetic proteins — that have positive or negative charges. When these charged peptides are put in solution, they stick together and form a separate liquid phase, a process called complex coacervation. The liquid wraps around virus capsids, holding the virus material together like a burrito’s tortilla.

“Coacervate materials are something that we actually see all of the time in our daily lives,” Perry said. “Many shampoos undergo coacervation. When you put the shampoo onto your wet hair, the water that is present dilutes the shampoo, causing it to phase separate and facilitating the removal of dirt and oil from your hair.”

Complex coacervation works for nonenveloped viruses, which have no lipid, or fatty layer, around them. Nonenveloped viruses include polio, rhinovirus (which causes the common cold) and hepatitis A.

Next Steps

Heldt and Perry received a $400,000 developmental research grant in March 2020 from the National Institutes of Health (NIH) to continue their research through early 2022, which includes exploring ways to reduce salt concentrations (used in the vaccine to break apart the coacervate phase when it is injected by altering peptide sequences). Additionally, the chemical engineers are working on ways to apply complex coacervation to enveloped viruses — like SARS-CoV-2 — which require a balance of tightness and compartmentalization in the lipid layer in a way nonenveloped viruses do not.

“Looking forward, we want to think more about the specific materials that we use in our coacervates,” Perry said. “Crowding alone isn’t a universal strategy to improve virus stability. We need to understand how different polymers interact with our viruses and how we can use this to create a toolbox that can be applied to future challenges.” 

As the taco bar of vaccine storage expands, the research shows that naturally occurring proteins improve our vaccines and make them more widely accessible around the world, refrigerated or not.

“The great thing about these amino acids is that they are the same building blocks as in our bodies,” Heldt said. “We’re not adding anything to the vaccines that aren’t already known to be safe.”

Solving the cold storage conundrum promises to improve access to vaccinations against viruses. Bypassing the cold chain with polypeptides and innovative chemical engineering stands to improve health care and reduce medical emergencies around the world.

Think about your favorite pair of winter socks. Are they wool, cotton or synthetic? Ankle or knee-high? What color are they?

Perhaps you’ve never really given it much thought, but the perfect pair of winter socks has been one of humanity’s great aspirations since people figured out that warm toes are generally preferable to cold ones.

And as any knitter or crocheter could tell you, socks are much more complicated than we give them credit for. Did you know there are seven parts to a sock? Cuff, leg, heel flap, turned heel, gusset, foot and toe — each component is necessary. But can the sock as we know it be improved upon?

Better Fibers

For thousands of years, the primary method for making socks was to knit, sew or weave them by hand. If anyone has ever knit you a pair of socks, it’s a sign they truly love you — hand knit socks take many hours to make. When the first knitting machine, the stocking frame, was invented in the 16th century — allegedly by a man whose love was spurned by a woman more passionate about knitting than about marriage — it allowed socks to be made in a fraction of the time.

Today’s industrial knitting processes use the same principle as the device invented in 1589; the first industrial revolution traces its beginnings to the stocking frame, which allowed mechanization of a sector of the textiles industry. And surely the tech can be improved upon. 

Electrospinning is a technique that uses electric fields to manipulate polymers to form fine fibers in the nano- and micro-range. Smitha Rao, assistant professor of biomedical engineering, researches biomedical applications of electrospun fibers for scaffolding and electrical sensing — the fibers are incredibly strong and can be embedded with sensors.

“A challenge I pose my students is to electrospin a spider web-like structure,” Rao said. “It is a structure that can support a lot of weight, not just because of the spider silk but because of the pattern it creates.”

Naturally occurring nanofibers such as collagen, keratin and others support specific biomedical functions as mechanical support, bio-signaling and bio-transportation. Along with replicating the properties of the natural materials, electrospinners can mimic the patterns of natural materials, which can be repeated several times one on top of another, weaving a beautiful and practical tapestry.

“Just like specific ingredients go into making a delectable cookie, electrospinning uses electric field, solvents and polymers to produce fibers,” Rao said. “Different sizes, patterns and features can be obtained by changing any or all of these parameters.”

But while many socks are created to be beautiful, they are a prime example of form following function.

“A more practical use here in the Upper Peninsula would be winter socks,” Rao said. “Electrospun socks with conductive silver embedded in the weave would make an ideal antimicrobial sock while also keeping your feet toasty warm.”

Sensory Stitches

Ye Sun, assistant professor of mechanical engineering—engineering mechanics and affiliated assistant professor of biomedical engineering, received an National Science Foundation (NSF) CAREER Award earlier this year that recognizes outstanding achievement by early career faculty. The research and development grant is for Sun’s project “System-on-Cloth: A Cloud Manufacturing Framework for Embroidered Wearable Electronics.” 

Sun’s research looks to replace wearable health monitoring devices with embroidered electronics and to build a manufacturing network and cloud-based website where stitch generation orders can be made.

Sun said a functional sock — one that could monitor blood pressure, gait or glucose levels—could provide a noninvasive method by which to provide medical interventions through sensors that could provide cues to the wearer to perform a specific action.

“Say if a child whose feet when they walk turn too far inward or outward could be corrected how they place their feet,” Sun said. “A specialized sock could not only monitor gesture and gait, but could also give intervention to the child. It could vibrate as a warning to the child to pay attention to how they place their feet, and the socks additionally could be powered to give a force in an opposite direction if necessary.”

Stop the Sagging

But what if the socks you’re wearing lose their elasticity and just won’t stay up? The answer to that could be smart adhesives. 

“Smart adhesives are adhesives that could be turned ‘on’ and ‘off’,” said Bruce Lee, associate professor of biomedical engineering.

“Adhesives could be used to keep socks in place so that they do not slump down,” Lee said. “However, removal of the adhered socks could cause a lot of pain and potentially lost hairs. If one could use a smart adhesive, one could turn it ‘off’ first so that the adhered socks could be more easily and painlessly removed.”

Lee’s former advisee, Ameya Narkar, focused his doctoral work on smart adhesives inspired by mussel adhesive chemistry — a small jolt of electricity can turn the stickiness on and off — but that’s not its only potential use.

While making the smart glue, the team of engineers discovered a handy byproduct: hydrogen peroxide. In microgel form, it reduces bacteria and virus ability to infect by at least 99 percent.

And these socks could potentially keep legs and ankles safe from bacteria and viruses, which could be beneficial to those suffering from diabetes or pregnancy-related swelling.

Warm Feet for All

One of Michigan Tech’s initiatives is to create technological solutions to enhance human health and quality of life. Socks may not seem like an important subject for academic discussion, but they’re a bit of creative engineering most people take for granted. Not everyone, though. Socks are some of the most needed items in homeless shelters. 

Karla Saari Kitalong, professor of humanities and director of the scientific and technical communication program, learned to knit scarves and potholders when she was 10 years old, but didn’t learn to knit socks until about two years ago. She now knits for Street Knits, an organization founded by Silke Feltz, who will soon graduate from the Rhetoric, Theory and Culture program, and who is now a faculty member at the University of Oklahoma. Street Knits is a humanitarian knitting charity that donates hand-knitted articles to the homeless.

“I’ve adopted the entrepreneur’s slogan, ‘the perfect is the enemy of the good,’” Kitalong said. “I try to focus on quantity, warmth and washability. A less-than-perfect wool blend sock is a blessing on a cold night. A suspension bridge or artificial limb needs to be closer to perfect.” 

Stitch by stitch, we can refine the design of an article of clothing that’s been under development for centuries. Warmth is a basic human need, and one day we will recognize socks are as necessary to quality of life as bridges, health monitoring and artificial limbs. Electrospinning, smart adhesives, sensors and compassion are the individual strands that may one day weave the perfectly engineered sock.

Original Article: https://www.mtu.edu/unscripted/stories/2018/december/engineering-the-perfect-winter-sock.html

Propelled by chemical changes in surface tension, microrobots surfing across fluid interfaces lead researchers to new ideas.

Spend an afternoon by a creek in the woods, and you’re likely to notice water striders — long-legged insects that dimple the surface of the water as they skate across. Or, dip one side of a toothpick in dish detergent before placing it in a bowl of water, and impress your grade schooler as the toothpick gently starts to move itself across the surface.

Both situations illustrate the concepts of surface tension and propulsion velocity. At Michigan Technological University, mechanical engineer Hassan Masoud and PhD student Saeed Jafari Kang have applied the lessons of the water strider and the soapy toothpick to develop an understanding of chemical manipulation of surface tension.

Their vehicle? Tiny surfing robots.

“During the past few decades, there have been many efforts to fabricate miniature robots, especially swimming robots,” said Masoud, an assistant professor in the mechanical engineering-engineering mechanics department. “Much less work has been done on tiny robots capable of surfing at the interface of water and air, what we call liquid interfaces, where very few robots are capable of propelling themselves.”

Beyond the obvious implications for future Lucasfilm droids designed for ocean planets (C-H2O?), what are the practical applications of surfing robots?

“Understanding these mechanisms could help us understand colonization of bacteria in a body,” Masoud said. “The surfing robots could be used in biomedical applications for surgery. We are unraveling the potential of these systems.”

Hunting for Answers and the Marangoni Effect

During his doctoral studies and postdoc appointment, Masoud conducted research to understand the hydrodynamics of synthetic microrobots and the mechanisms by which they move through fluid. While helping a colleague with an experiment, Masoud made an observation he couldn’t explain. An aha! moment came shortly thereafter. 

“During a conversation with a physicist, it occurred to me that what we had observed then was due to the release of a chemical species that changed the surface tension and resulted in motion of particles that we observed,” Masoud said.

That knowledge has led Masoud to continue analyzing the propulsion behavior of diminutive robots — only several microns in size — and the Marangoni effect, which is the transfer of mass and momentum due to a gradient of surface tension at the interface between two fluids. In addition to serving as an explanation for tears of wine, the Marangoni effect helps circuit manufacturers dry silicon wafers and can be applied to grow nanotubes in ordered arrays.

For Masoud’s purposes, the effect helps him design surfing robots powered by manipulating surface tension chemically. This solves a core problem for our imagined C-H2O: How would a droid propel itself across the surface of water without an engine and propeller?

Detailed in research findings published recently in the journal Physical Review Fluids, Masoud, Jafari Kang and their collaborators used experimental measurements and numerical simulations to demonstrate that the microrobot surfers propel themselves in the direction of lower surface tension — in reverse of the expected direction.

“We discovered that negative pressure is the primary contributor to the fluid force experienced by the surfer and that this suction force is mainly responsible for the reverse Marangoni propulsion,” Masoud said. “Our findings pave the way for designing miniature surfing robots. In particular, knowing that the direction of propulsion is altered by a change in the surrounding boundary can be harnessed for designing smart surfers capable of sensing their environment.”

Stability Studies on the Horizon

While Masoud’s work focused on understanding how microrobots can chemically manipulate their environment to create propulsion, future studies will zero in on the stability of these tiny surfers. Under what conditions are they stable? How do multiple surfers interact with each other? The interactions could provide insight into the swarm dynamics commonly seen in bacteria.

“We have just scratched the surface of learning the mechanisms through which the surfers — and other manipulators of surface tension — move,” Masoud said. “Now we are building understanding toward how to control their movement.”

Light-absorbing brown carbon aerosols, emitted by wildfires, remain longer in the atmosphere than expected, which could have implications for climate predictions.

Rising 2,225 meters into the air on an island in the Azores archipelago, Pico Mountain Observatory is an ideal place to study aerosols—particles or liquids suspended in gases—that have traveled great distances in the troposphere.

The troposphere is the portion of the atmosphere from the ground to about 10 kilometers in the air. Nearly all of the atmosphere’s water vapor and aerosol exist in the troposphere, and this is also where weather occurs. The Pico Observatory rises above the first layer of clouds in the troposphere, known as the atmospheric marine boundary layer. At that boundary the temperature drops rapidly, and relatively high humidity decreases as cooling air forces water to condense into cloud droplets.

Pico is often ringed in clouds, with its summit climbing above them. This feature allows scientists to study the aerosols above the boundary layer, including a set of three samples a research team at Michigan Technological University recently observed that challenges the way atmospheric scientists think about aerosol aging.

In “Molecular and physical characteristics of aerosol at a remote free troposphere site: Implications for atmospheric aging” published Tuesday, Oct. 2, 2018 in the journal Atmospheric Chemistry and Physics (DOI: 10.5194/acp-18-14017-2018), Michigan Tech chemists demonstrate that some aerosol particles—those that originate from wildfire combustion—are existing for longer periods in the atmosphere undergoing less oxidation than previously thought.

“Previously, brown carbon was expected to become mostly depleted within approximately 24 hours, but our results suggested the presence of significant brown carbon roughly a week downwind of its initial wildfire source in northern Quebec,” says Simeon Schum, a chemistry doctoral candidate at Michigan Tech and the paper’s first author.

This work builds on a previous paper published in the same journal, “Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume.”

Honey or marbles? Aerosol consistency explained

In order to determine where the molecules in aerosols originate, the team, led by the article’s corresponding author and associate professor of chemistry, Lynn Mazzoleni, used a Fourier Transform-Ion Cyclotron Resonance mass spectrometer, located at Woods Hole Oceanographic Institution, to analyze the chemical species of molecules from within the samples.

Aerosols, depending on their chemical and molecular composition, can have both direct and indirect effects on the climate. This is because some aerosols only scatter light, while others also absorb light, and others uptake water vapor, changing cloud properties. Aerosols play a cooling role in the atmosphere, but there are great uncertainties about the extent of forcing and climate effects.

Understanding how specific aerosols oxidize—break down—in the atmosphere is one piece in the puzzle of understanding how Earth’s climate changes. Aerosols take on a variety of consistencies, called viscosities, depending on their composition and their surroundings. Some have a consistency similar to olive oil or honey, and these tend to oxidize more rapidly than more solidified aerosol particles, which can become like pitch, or even marble-like.

Model simulations that indicate the airmass histories for three pollution events: PMO-1 (June 28, 2013), PMO-2 (July 6, 2014) and PMO-3 (June 21, 2015). The model simulations show the column integrated residence times over a 20-day transport time and their vertical distributions at given upwind times. The labels indicate the approximate locations of the center of the plume for each of the transport days. Further description can be found in Schum et al. Atmospheric Chemistry and Physics, 2018.

The three samples analyzed by the Michigan Tech team are named PMO-1, PMO-2 and PMO-3. PMO-1 and PMO-3 traveled to Pico in the free troposphere, while PMO-2 traveled to Pico in the boundary layer. Aerosols are less likely to occur in the free troposphere than in the boundary layer, but pyro-convection from wildfires can lift the particles higher up in the air. Though PMO-2 had been in the atmosphere for only two to three days, it had oxidized more than PMO-1 and PMO-3, which had been in the atmosphere roughly seven days and were estimated to be glassy in consistency.

“We were puzzled by the substantial difference between PMO-2 compared to PMO-1 and PMO-3. So, we asked ourselves why we would see aerosols at the station which were not very oxidized after they had been in the atmosphere for a week,” says Mazzoleni. “Typically, if you put something into the atmosphere, which is an oxidizing environment, for seven to 10 days, it should be very oxidized, but we weren’t seeing that.”

Cold and dry aerosols

Schum said the research team hypothesized that the first and third samples had oxidized more slowly because of the free tropospheric transport path of the aerosol after being injected to that level by wildfires in Quebec. Such a path toward Pico meant lower average temperature and humidity causing the particles to become more solid, and therefore less susceptible to oxidative destruction processes in the atmosphere.

That a particle would oxidize at a slower rate despite more time in the atmosphere because of its physical state provides new insight toward better understanding how particles affect the climate.

“Wildfires are such a huge source of aerosol in the atmosphere with a combination of cooling and warming properties, that understanding the delicate balance can have profound consequences on how accurately we can predict future changes,” says Claudio Mazzoleni, professor of physics and one of the authors of the paper.

As wildfires increase in size and frequency in the world’s arid regions, more aerosol particles could be injected into the free troposphere where they are slower to oxidize, contributing another important consideration to the study of atmospheric science and climate change.

In the field of cancer research, the idea that scientists can disrupt cancer growth by changing the environment in which cancerous cells divide is growing in popularity. The primary way researchers have tested this theory is to conduct experiments using animals.

Smitha Rao’s cell scaffolding research aims to replace animal testing in cancer research with electrospun synthetics.

Rao, assistant professor of biomedical engineering at Michigan Technological University, recently published “Engineered three-dimensional scaffolds modulating fate of breast cancer cells using stiffness and morphology related cell adhesion” in the journal IEEE Open Journal of Engineering in Medicine and Biology.

Rao’s coauthors are doctoral student Samerender Hanumantharao, master’s student Carolynn Que and undergraduate student Brennan Vogl, all Michigan Tech biomedical engineering students.

When cells grow inside the body, they require something known as an extra-cellular matrix (ECM) on which to grow, just like a well-built house requires a strong foundation. To study how cells grow on ECMs, researchers need to source the matrices from somewhere.

“Synthetic ECMs are created by electrospinning matrices from polymers such as polycaprolactone and are more consistent for research than using cells from different kinds of animals,” Hanumantharao said.

“In my lab the focus has been on standardizing the process and using synthetic materials to keep the same chemical formulation of a scaffold, but change the physical structure of the fibers that are produced,” Rao said, noting that changing the type of polymer or adding solvents to polymers introduces too many variables, which could affect the way cells grow on the scaffolds. Rao and her fellow researchers, therefore, can compare separate cell lines with different scaffold alignments by changing just one aspect of the experiment: voltage.

By changing the voltage at which the polymer is spun, the researchers can alter the shape of the scaffolds, whether honeycombed, mesh or aligned. Rao’s team published recently in Royal Chemistry Society Advances about manipulating electric fields to achieve different scaffold patterns. Rao’s team is working with Dipole Materials to explore scaling up the process.

Rao and her fellow researchers used four different cell lines to test the efficacy of the electrospun scaffolds: 184B5, which is normal breast tissue, as a control; MCF-7, a breast adenocarcinoma; MCF10AneoT, a premalignant cell line; and MDA-MB-231, a triple negative adenocarcinoma-metastatic, a very difficult-to-detect cancer.

“We can study why and how cancer cells metastasize,” Rao said. “We can understand in a true 3D system why pre-metastatic cells become metastatic, and provide tools to other researchers to study signaling pathways that change between pre-malignant and malignant cells.”

In addition, the research has uncovered information for another area of study: In what type of cellular environment do malignant cancer cells grow best? Rao’s group discovered that the triple-negative breast cancer cells preferred honeycomb scaffolds while adenocarcinoma cells favored mesh scaffolds and premalignant cells preferred the aligned scaffolds. In the future, scientists may be able to engineer cell scaffolding—stiffness, structure and shape—to make the area around a tumor in a person’s body a far less hospitable place for cancer cells to grow.