The new findings appear in the journal Nature Communications, in a paper by postdoc Yi Ding, professors of materials science and engineering Alfredo Alexander-Katz and Caroline Ross, and three others.

“This is a discovery that was in some sense fortuitous,” says Alexander-Katz. “Everyone thought this was not possible,” he says, describing the team’s discovery of a phenomenon that allows the polymers to self-assemble in patterns that deviate from regular symmetrical arrays.

Self-assembling block copolymers are materials whose chain-like molecules, which are initially disordered, will spontaneously arrange themselves into periodic structures. Researchers had found that if there was a repeating pattern of lines or pillars created on a substrate, and then a thin film of the block copolymer was formed on that surface, the patterns from the substrate would be duplicated in the self-assembled material. But this method could only produce simple patterns such as grids of dots or lines.

In the new method, there are two different, mismatched patterns. One is from a set of posts or lines etched on a substrate material, and the other is an inherent pattern that is created by the self-assembling copolymer. For example, there may be a rectangular pattern on the substrate and a hexagonal grid that the copolymer forms by itself. One would expect the resulting block copolymer arrangement to be poorly ordered, but that’s not what the team found. Instead, “it was forming something much more unexpected and complicated,” Ross says.

There turned out to be a subtle but complex kind of order — interlocking areas that formed slightly different but regular patterns, of a type similar to quasicrystals, which don’t quite repeat the way normal crystals do. In this case, the patterns do repeat, but over longer distances than in ordinary crystals. “We’re taking advantage of molecular processes to create these patterns on the surface” with the block copolymer material, Ross says.

This potentially opens the door to new ways of making devices with tailored characteristics for optical systems or for “plasmonic devices” in which electromagnetic radiation resonates with electrons in precisely tuned ways, the researchers say. Such devices require very exact positioning and symmetry of patterns with nanoscale dimensions, something this new method can achieve.

Katherine Mizrahi Rodriguez, who worked on the project as an undergraduate, explains that the team prepared many of these block copolymer samples and studied them under a scanning electron microscope. Yi Ding, who worked on this for his doctoral thesis, “started looking over and over to see if any interesting patterns came up,” she says. “That’s when all of these new findings sort of evolved.”

The resulting odd patterns are “a result of the frustration between the pattern the polymer would like to form, and the template,” explains Alexander-Katz. That frustration leads to a breaking of the original symmetries and the creation of new subregions with different kinds of symmetries within them, he says. “That’s the solution nature comes up with. Trying to fit in the relationship between these two patterns, it comes up with a third thing that breaks the patterns of both of them.” They describe the new patterns as a “superlattice.”

Having created these novel structures, the team went on to develop models to explain the process. Co-author Karim Gadelrab PhD ’19, says, “The modeling work showed that the emergent patterns are in fact thermodynamically stable, and revealed the conditions under which the new patterns would form.”

Ding says “We understand the system fully in terms of the thermodynamics,” and the self-assembling process “allows us to create fine patterns and to access some new symmetries that are otherwise hard to fabricate.”

He says this removes some existing limitations in the design of optical and plasmonic materials, and thus “creates a new path” for materials design.

So far, the work the team has done has been confined to two-dimensional surfaces, but in ongoing work they are hoping to extend the process into the third dimension, says Ross. “Three dimensional fabrication would be a game changer,” she says. Current fabrication techniques for microdevices build them up one layer at a time, she says, but “if you can build up entire objects in 3-D in one go,” that would potentially make the process much more efficient.

The research was funded by the Office of General Sciences of the U.S. Department of Energy. The team also included graduate student Hejin Huang.

Writing in the Journal of the Royal Society of Medicine, Professor John Ashton points to the recent announcement of a scheme to plant 130,000 trees in urban areas as a contribution to reducing pollution and global warming. While lacking in ambition, he writes, it gives a clue as to what might be possible by joining up the dots of green environmentalism and human burial.

The environmental and human health impacts of the fluids and materials used in embalming and coffins is a matter of growing interest and concern, writes Prof Ashton, and resonates with the recent move towards simpler funeral approaches, not least green funerals with biodegradable regalia and coffins in woodland areas.

With little prospect of finding burial space for those who seek it, he writes, there is a real opportunity of stepping up to the mark as boldly as the Victorians did with the Metropolitan Burial Act of 1852.

Prof Ashton concludes: “A glimpse of what might be possible with political will and imagination can be seen by what has happened alongside long-forgotten canals by neglect and default where wildlife corridors have evolved over time. It is time to revisit the public health roots of human burial and connect them to a new vision for a planet fit for future generations.”

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It has until now been believed that nerve signals for pain are always conducted more slowly than those for touch. The latter signals, which allow us to determine where we are being touched, are conducted by nerves that have a fatty sheath of myelin that insulates the nerve. Nerves with a thick layer of myelin conduct signals more rapidly than unmyelinated nerves. In contrast, the signalling of pain in humans has been thought to be considerably slower and carried out by nerves that have only a thin layer of myelin, or none at all.

In monkeys and many other mammals, on the other hand, part of the pain-signalling system can conduct nerve signals just as fast as the system that signals touch. The scientists speculated whether such a system is also present in humans.

“The ability to feel pain is vital to our survival, so why should our pain-signalling system be so much slower than the system used for touch, and so much slower than it could be?” asks Saad Nagi, principal research engineer of the Department of Clinical and Experimental Medicine and the Center for Social and Affective Neuroscience (CSAN) at Linköping University.

To answer this, the scientists used a technique that allowed them to detect the signals in the nerve fibres from a single nerve cell. They examined 100 healthy volunteers and looked for nerve cells that conducted signals as rapidly as the nerve cells that detect touch, but that had the properties of pain receptors, otherwise known as nociceptors. Pain receptors are characterised by the ability to detect noxious stimuli, such as pinching and abrasion of the skin, while not reacting to light touch. The researchers found that 12% of thickly myelinated nerve cells had the same properties as pain receptors, and in these nerve cells the conduction speed was as high as in touch-sensitive nerve cells.

The next step of the scientists’ research was to determine the function of these ultrafast pain receptors. By applying short electrical pulses through the measurement electrodes, they could stimulate individual nerve cells. The volunteers described that they experienced sharp or pinprick pain.

“When we activated an individual nerve cell, it caused a perception of pain, so we conclude that these nerve cells are connected to pain centres in the brain,” says Saad Nagi.

The research team also investigated patients with various rare neurological conditions. One group of people had, as adults, acquired nerve damage that led to the thickly myelinated nerve fibres being destroyed, while the small fibres were spared. These patients cannot detect light touch. The scientists predicted that the loss of myelinated nerve fibres should also affect the rapidly conducting pain system they had identified. It turned out that these people had an impaired ability to experience mechanical pain. Examination of patients with two other rare neurological conditions gave similar results. These results may be highly significant for pain research, and for the diagnosis and care of patients with pain.

“It’s becoming evident that thickly myelinated nerve fibres contribute to the experience of pain when it has a mechanical cause. Our results challenge the textbook description of a rapid system for signalling touch and a slower system for signalling pain. We suggest that pain can be signalled just as rapidly as touch,” says Saad Nagi.

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University of Exeter scientists scoured existing published studies and Twitter for shark and ray entanglements, and found reports of more than 1,000 entangled individuals.

And they say the true number is likely to be far higher, as few studies have focussed on plastic entanglement among shark and rays.

The study says such entanglement — mostly involving lost or discarded fishing gear — is a “far lesser threat” to sharks and rays than commercial fishing, but the suffering it causes is a major animal welfare concern.

“One example in the study is a shortfin mako shark with fishing rope wrapped tightly around it,” said Kristian Parton, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.

“The shark had clearly continued growing after becoming entangled, so the rope — which was covered in barnacles — had dug into its skin and damaged its spine.

“Although we don’t think entanglement is a major threat to the future of sharks and rays, it’s important to understand the range of threats facing these species, which are among the most threatened in the oceans.

“Additionally, there’s a real animal welfare issue because entanglements can cause pain, suffering and even death.”

Co-author Professor Brendan Godley, co-ordinator of the university’s marine strategy, added: “Due to the threats of direct over-fishing of sharks and rays, and ‘bycatch’ (accidental catching while fishing for other species), the issue of entanglement has perhaps gone a little under the radar.

“We set out to remedy this. Our study was the first to use Twitter to gather such data, and our results from the social media site revealed entanglements of species — and in places — not recorded in the academic papers.”

The review of academic papers found reports of 557 sharks and rays entangled in plastic, spanning 34 species in oceans including the Atlantic, Pacific and Indian. Almost 60% of these animals were either lesser spotted dogfish, spotted ratfish or spiny dogfish.

On Twitter, the researchers found 74 entanglement reports involving 559 individual sharks and rays from 26 species including whale sharks, great whites, tiger sharks and basking sharks.

Both data sources suggested “ghost” fishing gear (nets, lines and other equipment lost or abandoned) were by far the most common entangling objects. Other items included strapping bands used in packaging, polythene bags and rubber tyres.

The study identified factors that appear to put certain species more at risk:

• Habitat — sharks and rays in the open ocean appear more likely to get entangled, as do those living on the sea floor, where materials such as nets loaded with dead fish sink and attract predators, which in turn get stuck.
• Migration — species that cover long distances appear at more at risk of encountering plastic waste.
• Body shape — sharks seem to be at greater risk than rays. Species with unusual features — such as manta rays, basking sharks and sawfish — are also at more risk.

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During the surgery, Australian surgeons attached functioning nerves above the spinal injury to paralysed nerves below the injury. Two years after surgery, and following intensive physical therapy, participants were able to reach their arm out in front of them and open their hand to pick up and manipulate objects. Restoring elbow extension improved their ability to propel their wheelchair and to transfer into bed or a car.

They can now perform everyday tasks independently such as feeding themselves, brushing teeth and hair, putting on make-up, writing, handling money and credit cards, and using tools and electronic devices.

The findings suggest that nerve transfers can achieve similar functional improvements to traditional tendon transfers, with the benefit of smaller incisions and shorter immobilisation times after surgery.

In 10 participants, nerve transfers were uniquely combined with tendon transfers allowing different styles of reconstruction to be performed in each hand, and enabling participants to benefit from the innate strengths of both tendon and nerve transfers. Nerve transfers restored more natural movement and finer motor control in one hand, and tendon transfers restored more power and heavy lifting ability in the other hand.

While only a small study, researchers say that nerve transfers are a major advance in the restoration of hand and arm function, and offer another safe, reliable surgical option for people living with tetraplegia.

Nevertheless, four nerve transfers failed in three participants and the authors conclude that more research will be needed to determine which people are the best candidates to select for nerve transfer surgery to minimise the incidence of failure.

“For people with tetraplegia, improvement in hand function is the single most important goal. We believe that nerve transfer surgery offers an exciting new option, offering individuals with paralysis the possibility of regaining arm and hand functions to perform everyday tasks, and giving them greater independence and the ability to participate more easily in family and work life,” says Dr Natasha van Zyl from Austin Health in Melbourne, Australia who led the research.

“What’s more, we have shown that nerve transfers can be successfully combined with traditional tendon transfer techniques to maximise benefits. When grasp and pinch was restored using nerve transfers in one hand and tendon transfers in the other, participants consistently reporting that they liked both hands for different reasons and would not choose to have two hands reconstructed in the same way.”

Traditionally, upper limb function has been reconstructed using tendon transfer surgery, during which muscles that still work, but are designed for another function, are surgically re-sited to do the work of muscles that are paralysed. In contrast, nerve transfers allow the direct reanimation of the paralysed muscle itself. Additionally, nerve transfers can re-animate more than one muscle at a time, have a shorter period of immobilisation after surgery (10 days in a sling vs 6-12 weeks in a brace for a nerve transfer for elbow extension), and avoid the technical problems associated with of tendon transfer surgery including tendon tensioning during surgery and mechanical failure (stretch or rupture) after surgery.

Previous single case reports and small retrospective studies have shown nerve transfer surgery to be feasible and safe in people with tetraplegia. But this is the first prospective study to use standardised functional outcome measures and combinations of multiple nerve and tendon transfer surgeries.

In total the study recruited 16 young adults (average age 27 years) with traumatic, early (less than 18 months post injury) spinal cord injury to the neck (C5-C7), who were referred to Austin Health in Melbourne for restoration of function in the upper limb. Most were the result of motor vehicle accidents or sports injuries.

Participants underwent single or multiple nerve transfers in one or both upper limbs to restore elbow extension, grasp, pinch, and hand opening. This involved taking working nerves to expendable muscles innervated above the spinal injury and attaching them to the nerves of paralysed muscles innervated below the injury to restore voluntary control and reanimate the paralysed muscle.

For example, the surgeons selected the nerve supplying the teres minor muscle in the shoulder as a donor nerve and attached it to the nerve supplying the triceps that activates the muscles that extend (straighten) the elbow. To restore grasp and pinch the nerve to a spare wrist extensor muscle was transferred to the anterior interosseous nerve.

In total, 59 nerve transfers were completed in 16 participants (13 men and three women; 27 limbs). In 10 participants (12 limbs), nerve transfers were combined with tendon transfers to improve hand function.

Participants completed assessments on their level of independence related to activities of daily living (e.g., self-care, toilet, upper limb function, muscle power, grasp and pinch strength, and hand opening ability) before surgery, one year after surgery, and again two years later. Two participants were lost to follow up, and there was one death (unrelated to the surgery).

At 24 months, significant improvements were noted in the hands ability to pick up and release several objects within a specified time frame and independence. Prior to surgery, none of the participants were able to score on the grasp or pinch strength tests, but 2 years later pinch and grasp strength were high enough to perform most activities of daily living.

Three participants had four failed nerve transfers — two had a permanent decrease in sensation, and two had a temporary decrease in wrist strength that resolved by 1 year after surgery. Overall, surgery was well tolerated. Five serious adverse events were recorded (including a fall from a wheelchair with femur fracture), but none were related to the surgery.

Despite these achievements, nerve transfer surgery still has some limitations. For the best results nerve transfers should ideally be performed within 6-12 months of injury. Additionally, it can take months after nerve transfer for nerve regrowth into the paralysed muscle to occur and for new movement to be seen, and years until full strength is achieved. However, the authors note that one of the benefits of nerve transfers is that most movements not successfully restored by nerve transfers can still be restored using tendon transfers.

Discussing the implications of the findings in a linked comment, Dr Ida Fox from Washington University in the USA writes, “Stem cells and neuroprostheses could change the landscape of regenerative medicine in the future. For now, nerve transfers are a cost-effective way to harness the body’s innate capability to restore movement in a paralysed limb. As nerve transfers are adopted and their uses adapted, careful ongoing outcomes research — including comparison of nerve versus tendon transfer outcomes, which nerve transfers produce the greatest functional improvements, and optimal timings for surgery after injury — is paramount to advancing the field. Detailed study of the reasons for nerve transfer failure is also required, as is improving our understanding of the effects of biopsychosocial factors (including access to information and care, psychological readiness, and social support) on patient decision making and outcomes.”

They confirmed that the belt of brown macroalgae called Sargassum forms its shape in response to ocean currents, based on numerical simulations. It can grow so large that it blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico. This happened last year when more than 20 million tons of it — heavier than 200 fully loaded aircraft carriers — floated in surface waters and some of which wreaked havoc on shorelines lining the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida.

The team also used environmental and field data to suggest that the belt forms seasonally in response to two key nutrient inputs: one human-derived, and one natural. In the spring and summer, Amazon River discharge adds nutrients to the ocean, and such discharged nutrients may have increased in recent years due to increased deforestation and fertilizer use. In the winter, upwelling off the West African coast delivers nutrients from deep waters to the ocean surface where the Sargassum grows.

“The evidence for nutrient enrichment is preliminary and based on limited field data and other environmental data, and we need more research to confirm this hypothesis,” said Dr. Chuanmin Hu of the USF College of Marine Science, who led the study and has studied Sargassum using satellites since 2006. “On the other hand, based on the last 20 years of data, I can say that the belt is very likely to be a new normal,” said Hu.

Hu spearheaded the work with first author Dr. Mengqiu Wang, a postdoctoral scholar in his Optical Oceanography Lab at USF. The team included others from USF, Florida Atlantic University, and Georgia Institute of Technology. The data they analyzed from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) between 2000-2018 indicates a possible regime shift in Sargassum blooms since 2011.

“The scale of these blooms is truly enormous, making global satellite imagery a good tool for detecting and tracking their dynamics through time,” said Woody Turner, manager of the Ecological Forecasting Program at NASA Headquarters in Washington.

In patchy doses in the open ocean, Sargassum contributes to ocean health by providing habitat for turtles, crabs, fish, and birds and producing oxygen via photosynthesis like other plants. “In the open ocean, Sargassum provides great ecological values, serving as a habitat and refuge for various marine animals. I often saw fish and dolphins around these floating mats,” Wang said.

But too much of this seaweed makes it hard for certain marine species to move and breathe, especially when the mats crowd the coast. When it dies and sinks to the ocean bottom at large quantities it can smother corals and seagrasses. On the beach, rotten Sargassum releases hydrogen sulfide gas and smells like rotten eggs, potentially presenting health challenges for people on beaches who have asthma, for example.

2011: A Tipping Point

Before 2011, most of the pelagic Sargassum in the ocean was primarily found floating in patches around the Gulf of Mexico and Sargasso Sea. The Sargasso Sea is located on the western edge of the central Atlantic Ocean and named after its popular algal resident. Christopher Columbus first reported Sargassum from this crystal-clear ocean in the 15th century, and many boaters of the Sargasso Sea are familiar with this seaweed.

In 2011, Sargassum populations started to explode in places it hadn’t been before, like the central Atlantic Ocean, and it arrived in gargantuan gobs that suffocated shorelines and introduced a new nuisance for local environments and economies. Some countries, such as Barbados, declared a national emergency last year because of the toll this once-healthy seaweed took on tourism.

“The ocean’s chemistry must have changed in order for the blooms to get so out of hand,” Hu said. Sargassum reproduces vegetatively, and it probably has several initiation zones around the Atlantic Ocean. It grows faster when nutrient conditions are favorable and when its internal clock ticks in favor of reproduction.

To unravel the mystery, the team analyzed fertilizer consumption patterns in Brazil, Amazon deforestation rates, Amazon River discharge, two years of nitrogen and phosphorus measurements taken from the central western parts of the Atlantic Ocean, among other ocean properties.

While the data are preliminary, the pattern seems clear: the explosion in Sargassum correlates to increases in deforestation and fertilizer use, both of which have increased since 2010.

A Recipe for a Doom and Gloom Bloom

The team identified key factors that are critical to bloom formation: a large seed population in the winter left over from a previous bloom, nutrient input from West Africa upwelling in winter, and nutrient input in the spring or summer from the Amazon River. In addition, Sargassum only grows well when salinity is normal and surface temperatures are normal or cooler.

The 2011 bloom was likely caused by Amazon River discharge in previous years, Wang said, but was driven to even larger proportions by the double whammy of upwelling in the eastern Atlantic and river discharge on the western Atlantic.

As noted in the satellite imagery, major blooms occurred in every year between 2011 and 2018 except 2013 — and the cocktail of ingredients necessary explains why. No bloom occurred in 2013 because the seed populations measured during winter of 2012 were unusually low, Wang said.

Hu also explained why the tipping point started in 2011 instead of 2010, even on the heels of significant Amazon discharge in 2009. Significant rain in 2009 introduced freshwater to the ocean, which reduced salinity. Plus, in 2010 the sea surface temperature was higher than normal. Sargassum didn’t bloom in either 2009 or 2010 because these conditions do not favor Sargassum growth.

“This is all ultimately related to climate change because it affects precipitation and ocean circulation and even human activities, but what we’ve shown is that these blooms do not occur because of increased water temperature,” Hu said. “They are probably here to stay.”

The team reports that a more detailed seasonal pattern likely to be recurring looks like this:

January: Sargassum in Central Atlantic provides the seeds for the subsequent spring-summer blooms

Jan-April: Sargassum develops into a bloom extending to the tropical Atlantic (some may reach Caribbean)

Apr — July: Blooms continue to develop into a Great Atlantic Sargassum Belt (extends northwestward by the North Brazil Current and North Equatorial Current, and eastward to the West Africa coast by the North Equatorial Counter Current)

After July: Bloom continues to the eastern Atlantic while overall abundance begins to decrease

Sept-Oct: Bloom gradually dissipates

Winter: Either the mats dissipate (as in 2012) or contribute to new blooms in the coming year

No Crystal Ball and More Work Needed

The Sargassum bloom in the Caribbean during the early parts of this year was even worse than last year, Hu said, and it’s likely to impact holiday vacations in the northern Caribbean and south Florida, including Dominican Republic, Puerto Rico, Jamaica, Quintana Roo, Florida Keys, Miami Beach, and Palm Beach.

In general, predicting future blooms is difficult, Hu said, because the blooms depend on a wide-ranging spectrum of factors that are hard to predict. There’s a lot left to understand, too, such as whether and how the Sargassum belt affects fisheries.

“We hope this provides a framework for improved understanding and response to this emerging phenomenon,” Hu said. “We need a lot more follow-on work.”