The researchers will present their work at the 2023 Conference on Computer Vision and Pattern Recognition (CVPR), which will take place from June 18 to 22 in Vancouver, Canada.

“By providing the robot with a better understanding of its surroundings in 3D, it can be deployed in more complex environments in the real world,” said study senior author Xiaolong Wang, a professor of electrical and computer engineering at the UC San Diego Jacobs School of Engineering.

The robot is equipped with a forward-facing depth camera on its head. The camera is tilted downwards at an angle that gives it a good view of both the scene in front of it and the terrain beneath it.

To improve the robot’s 3D perception, the researchers developed a model that first takes 2D images from the camera and translates them into 3D space. It does this by looking at a short video sequence that consists of the current frame and a few previous frames, then extracting pieces of 3D information from each 2D frame. That includes information about the robot’s leg movements such as joint angle, joint velocity and distance from the ground. The model compares the information from the previous frames with information from the current frame to estimate the 3D transformation between the past and the present.

The model fuses all that information together so that it can use the current frame to synthesize the previous frames. As the robot moves, the model checks the synthesized frames against the frames that the camera has already captured. If they are a good match, then the model knows that it has learned the correct representation of the 3D scene. Otherwise, it makes corrections until it gets it right.

The 3D representation is used to control the robot’s movement. By synthesizing visual information from the past, the robot is able to remember what it has seen, as well as the actions its legs have taken before, and use that memory to inform its next moves.

“Our approach allows the robot to build a short-term memory of its 3D surroundings so that it can act better,” said Wang.

The new study builds on the team’s previous work, where researchers developed algorithms that combine computer vision with proprioception — which involves the sense of movement, direction, speed, location and touch — to enable a four-legged robot to walk and run on uneven ground while avoiding obstacles. The advance here is that by improving the robot’s 3D perception (and combining it with proprioception), the researchers show that the robot can traverse more challenging terrain than before.

“What’s exciting is that we have developed a single model that can handle different kinds of challenging environments,” said Wang. “That’s because we have created a better understanding of the 3D surroundings that makes the robot more versatile across different scenarios.”

The approach has its limitations, however. Wang notes that their current model does not guide the robot to a specific goal or destination. When deployed, the robot simply takes a straight path and if it sees an obstacle, it avoids it by walking away via another straight path. “The robot does not control exactly where it goes,” he said. “In future work, we would like to include more planning techniques and complete the navigation pipeline.”

Video: https://youtu.be/vJdt610GSGk

Paper title: “Neural Volumetric Memory for Visual Locomotion Control.” Co-authors include Ruihan Yang, UC San Diego, and Ge Yang, Massachusetts Institute of Technology.

This work was supported in part by the National Science Foundation (CCF-2112665, IIS-2240014, 1730158 and ACI-1541349), an Amazon Research Award and gifts from Qualcomm.

“We are not advocating the use of alcohol to reduce the risk of heart attacks or strokes because of other concerning effects of alcohol on health,” says senior author and cardiologist Ahmed Tawakol, MD, co-director of the Cardiovascular Imaging Research Center at Massachusetts General Hospital. “We wanted to understand how light to moderate drinking reduces cardiovascular disease, as demonstrated by multiple other studies. And if we could find the mechanism, the goal would be to find other approaches that could replicate or induce alcohol’s protective cardiac effects without the adverse impacts of alcohol.”

Previous epidemiological studies have suggested that light to moderate alcohol consumption (1 drink per day for women and 1 to 2 drinks per day for men) is associated with a lower risk of cardiovascular disease. But it was unknown whether alcohol was inducing cardiovascular benefits, or whether light/moderate drinkers’ health behaviors, socioeconomic status, or other factors protected their hearts.

The study, led by K Mezue and M Osborne, included more than 50,000 individuals enrolled in the Mass General Brigham Biobank. The first part of the study evaluated the relationship between light/moderate alcohol consumption and major adverse cardiovascular events after adjusting for a range of genetic, clinical, lifestyle, and socioeconomic confounders. The researchers found that light/moderate alcohol consumption was associated with a substantial reduction in the risk of cardiovascular disease events, even after accounting for those other factors.

Next, they studied a subset of 754 individuals who had undergone previous PET/CT brain imaging (primarily for cancer surveillance) to determine the effect of light/moderate alcohol consumption on resting stress-related neural network activity.

The brain imaging showed reduced stress signaling in the amygdala, the brain region associated with stress responses, in individuals who were light to moderate drinkers compared to those who abstained from alcohol or who drank little. And when the investigators looked at these individuals’ history of cardiovascular events, they found fewer heart attacks and strokes in light to moderate drinkers. “We found that the brain changes in light to moderate drinkers explained a significant portion of the protective cardiac effects,” says Tawakol.

It’s long been known that alcohol reduces the amygdala’s reactivity to threatening stimuli while individuals are drinking. The current study is the first to indicate that light to moderate alcohol consumption has longer-term neurobiological effects in dampening activity in the amygdala, which may have a significant downstream impact on the cardiovascular system.

“When the amygdala is too alert and vigilant, the sympathetic nervous system is heightened, which drives up blood pressure and increases heart rate, and triggers the release of inflammatory cells,” explains Tawakol. “If the stress is chronic, the result is hypertension, increased inflammation, and a substantial risk of obesity, diabetes, and cardiovascular disease.”

Finally, the investigators examined whether light/moderate alcohol would be even more effective at reducing heart attacks and strokes in people who are prone to a chronically higher stress response, such as those with a history of significant anxiety. They found that, within the 50,000-patient sample, light to moderate drinking was associated with nearly double the cardiac-protective effect in individuals with a history of anxiety compared with others.

Yet while light/moderate drinkers lowered their risk for cardiovascular disease, the study also showed that any amount of alcohol increases the risk of cancer. And at higher amounts of alcohol consumption — more than 14 drinks a week — heart attack risk started to increase while overall brain activity started to decrease (which may be associated with adverse cognitive health).

The authors concluded that research should focus on finding new interventions that reduce the brain’s stress activity without the deleterious effects of alcohol. The research team is currently studying the effect of exercise, stress-reduction interventions such as meditation, and pharmacological therapies on stress-associated neural networks and how they might induce cardiovascular benefits.

Co-authors include Kenechukwu Mezue and Michael T. Osborne.

This study was supported by the National Institutes of Health.

One of the most promising renewable energy carriers is clean hydrogen, which is produced without fossil fuels.

It’s a promising idea because the most abundant element in the universe is hydrogen, found in 75 percent of all matter. Moreover, a hydrogen molecule has two paired atoms — Gemini twins that are both non-toxic and highly combustible.

Hydrogen’s combustive potential makes it an attractive subject for energy researchers around the world.

At Pacific Northwest National Laboratory (PNNL), a team is investigating hydrogen as a medium for storing and releasing energy, largely by cracking its chemical bonds. Much of their work is linked to the Hydrogen Materials-Advanced Research consortium (HyMARC) at the Department of Energy (DOE).

Hydrogen storage not yet optimized

One PNNL research focus relates to optimizing hydrogen storage, a stubborn issue. To date, there is no completely safe, cost-effective, and energy-efficient way to store hydrogen at large scales.

PNNL researchers recently coauthored a paper that investigates a baking soda solution as a means of storing hydrogen. The study has already been dubbed a “hot paper” by the journal itself, Green Chemistry, published by the Royal Society of Chemistry. That means that it has had a lot of clicks showing interest.

The hydrogen-based storage efforts at PNNL are funded by the DOE’s Hydrogen and Fuel Cell Technologies Office in the Office of Energy Efficiency and Renewable Energy (EERE). The research advances the DOE’s H2@Scale initiative as well as the agency’s Hydrogen Shot.

The new paper’s two main authors are chemist and PNNL Laboratory Fellow Thomas Autrey and his colleague Oliver Gutiérrez, an expert in making chemical reactions speedy and cost-effective.

“You have to be a little creative,” said Autrey, who is amused at how common, cheap, and mild baking soda is as a potential answer to a big problem. “Not every chemical is going to be efficient at storing hydrogen. You have to work with what Mother Nature gives you.”

Clean hydrogen for long-term energy needs

Autrey, Gutiérrez, and others at PNNL see long-duration energy storage as the key to hydrogen’s future as a carrier of renewable energy.

Current battery technology is designed for several hours of storage. In a renewable energy grid, batteries can handle about 80 percent of storage needs.

But “the last 20 percent will take unique approaches,” said Autrey. “We will want to store the excess energy to be prepared for Dunkelflaute.”

That’s a German word describing conditions without enough solar and wind energy potential. During the dark, windless periods of Dunkelflaute, grids need a way to store energy for more than just several hours.

Seasonal storage capability like this is one of hydrogen’s attractions. So is the fact that hydrogen storage can happen anywhere that it is “geographically agnostic,” as experts say. Hydropower, for example, requires differences in elevation to store excess water to make power. Hydrogen storage requires no special conditions related to geography.

In addition, said Autrey, as scales get larger, hydrogen gets more economical. It is cheaper to buy a few additional hydrogen storage tanks than to buy a lot of batteries.

Finding the best way for hydrogen storage

Clean hydrogen has great promise as an energy source. A process called electrolysis, for instance, can split water into hydrogen and oxygen. In the best of worlds, the power for electrolysis would come from renewable energy sources, including solar, wind, and geothermal.

However, there is one stubborn challenge: to produce hydrogen more cheaply.

To address that, in 2021 the DOE announced its Energy Earthshots initiative, a series of six steps to underwrite breakthroughs in clean-energy technology. Introduced first was the Hydrogen Shot, a quest to reduce the cost of hydrogen to from $5 to $1 per kilogram in a decade — an 80 percent reduction.

Beyond getting clean hydrogen production costs down, “you have to figure out how to move and store it,” said Autrey, which are steps that can send prices back up.

But finding the ideal medium for hydrogen storage has been elusive.

Hydrogen can be compressed into a gas, but that requires very high pressures — up to 10,000 pounds per square inch. A safe storage tank would need walls of very thick steel or expensive space-grade carbon fiber.

How about cryogenic liquid hydrogen? This is a proven storage medium but requires getting and keeping something so cold (-471 F, or -279.4 C) that peripheral energy costs are significant.

What seems to hold the most promise are molecules that are liquids, optimized to store and release hydrogen. Jamie Holladay, a sustainable energy expert, recently directed PNNL-led research on simpler and more efficient strategies for liquefying hydrogen.

Using such liquids as a storage medium have the advantage of keeping existing energy infrastructure in place, including pipelines, trucks, trains, and taker ships, said Gutierrez.

The bicarbonate-formate cycle

Want to bake cookies? Or store hydrogen energy? Baking soda could be the ticket. This mild, cheap sodium salt of bicarbonate is non-toxic and Earth-abundant.

Not baking soda exactly. The PNNL team is investigating the hydrogen energy storage properties of the long-studied bicarbonate-formate cycle. (Formate is a safe, mild liquid organic molecule.)

Here’s how it works: Solutions of formate ions (hydrogen and carbon dioxide) in water carry hydrogen based on non-corrosive alkali metal formate. The ions react with water in the presence of a catalyst. That reaction makes hydrogen and bicarbonates the “baking soda” Autrey admires for its absence of environmental impacts.

With the right mild tweaks in pressure, the bicarbonate-formate cycle can be reversed. That provides an on-off switch for an aqueous solution that can alternately store or release hydrogen.

Before baking soda, the PNNL hydrogen storage team looked at ethanol as a liquid organic hydrogen carrier, the industry’s blanket term for storage and transport media. In tandem, they developed a catalyst that releases the hydrogen.

Catalysts are designer additives that speed the processes used to make and break chemical bonds in an energy-efficient way.

In May 2023, for a project related to the PNNL effort, EERE granted OCOchem of Richland, Washington, $2.5 million in funding over two years to develop an electrochemical process that makes formate and formic acid from carbon dioxide. The process would bind carbon dioxide with the hydrogen located in water’s iconic chemical bond, H₂O.

In a partnership just starting, PNNL will develop ways to release hydrogen from the OCOchem products.

Hydrogen storage that ‘looks like water’

In the world of hydrogen storage research, the bicarbonate-formate cycle has created a buzz for quite some time. After all, it is based on materials that are abundant, non-flammable, and non-toxic.

The cycle is built on an aqueous storage solution so mild it “looks like water,” said Autrey. “You can put out a fire with it.”

But for formate-bicarbonate salts to become a viable means of storing hydrogen energy, researchers must still develop economically feasible scenarios. So far, the technology stores hydrogen at only 20 kilograms per cubic meter, compared to liquid hydrogen’s industry standard of 70.

More fundamentally, said Autrey, researchers need a systems-level understanding of the required electrochemistry and catalysis. In engineering terms, to date, the idea of a workable bicarbonate-formate cycle has a low technical readiness level.

“If we solve the catalysis problems,” he added, “we could get some real interest.”

‘An amazing shiny thing’

On the plus side, the salt solutions under consideration at PNNL release hydrogen upon reaction with water. They also operate at moderate temperatures and low pressures.

In theory, at least, as Autrey and Gutiérrez describe in their 2023 paper, the bicarbonate-formate cycle represents “a feasible green alternative for storing and transporting energy” from hydrogen.

The baking soda idea is also at the nexus of what the 2023 paper calls “several urgent scientific challenges.”

Among them are how to make a hydrogen storage media from captured excess carbon dioxide. And even to use the same media to store electrons, which offers the promise of direct formate fuel cells.

In addition, the PNNL work could provide insights for catalysis in the aqueous (water) phase. For now, the PNNL team is using palladium as their candidate catalyst. Their efforts include finding ways to make the rare metal more stable, reusable, and longer-lived.

In all, the baking soda idea “is this amazing shiny thing” for hydrogen storage, said Autrey. “What’s exciting are the possibilities.”

“Before, we thought that it was impossible for liquid metal to adhere to non-wetting surfaces so easily, but here it can adhere to various surfaces only by adjusting the pressure, which is very interesting,” said Bo Yuan, a scientist at Tsinghua University and the first author of the study.

Scientists seeking to combine liquid metal with traditional materials have been impeded by liquid metal’s extremely high surface tension, which prevents it from binding with most materials, including paper. To overcome this issue, previous research has mainly focused on a technique called “transfer printing,” which involves using a third material to bind the liquid metal to the surface. But this strategy comes with drawbacks — adding more materials can complicate the process and may weaken the end product’s electrical, thermal, or mechanical performance.

To explore an alternative approach that would allow them to directly print liquid metal on substrates without sacrificing the metal’s properties, Yuan and colleagues applied two different liquid metals (eGaln and BilnSn) to various silicone and silicone polymer stamps, then applied different forces as they rubbed the stamps onto paper surfaces.

“At first, it was hard to realize stable adhesion of the liquid metal coating on the substrate,” said Yuan. “However, after a lot of trial and error, we finally had the right parameters to achieve stable, repeatable adhesion.”

The researchers found that rubbing the liquid metal-covered stamp against the paper with a small amount of force enabled the metal droplets to bind effectively to the surface, while applying larger amounts of force prevented the droplets from staying in place.

Next, the team folded the metal-coated paper into a paper crane, demonstrating that the surface can still be folded as usual after the process is completed. And after doing so, the modified paper still maintains its usual properties.

While the technique appears promising, Yuan noted that the researchers are still figuring out how to guarantee that the liquid metal coating stays in place after it has been applied. For now, a packaging material can be added to the paper’s surface, but the team hopes to figure out a solution that won’t require it.

“Just like wet ink on paper can be wiped off by hand, the liquid metal coating without packaging here also can be wiped off by the object it touches as it is applied,” said Yuan. “The properties of the coating itself will not be greatly affected, but objects in contact may be soiled.”

In the future, the team also plans to build on the method so that it can be used to apply liquid metal to a greater variety of surfaces, including metal and ceramic.

“We also plan to construct smart devices using materials treated by this method,” said Yuan.

This work was supported by China Postdoctoral Science Foundation, the National Nature Science Foundation of China, and the cooperation funding between Nanshan and Tsinghua SIGS in science and technology.