Unlocking the mechanical secrets of giant Amazonian waterlilies

Giant Amazonian waterlilies at Oxford Botanic Garden
Credit: Chris Thorogood

Researchers studying giant Amazonian waterlilies grown at the University's Botanic Garden have unraveled the engineering enigma behind the largest floating leaves in nature.

In a study published recently in Science Advances, researchers found that the distinctive pattern on the underside of the gargantuan leaves is the secret to the success of the giant Amazonian waterlily (genus Victoria).

The crisscross framework makes up the vascular structure of the lily pad (or leaf), supporting its large surface area and keeping it afloat. The giant leaves can grow 40cm a day, reaching nearly 3m in diameter – ten times larger than any other species of waterlily – and carry the weight of a small child.

Dr Chris Thorogood, Deputy Director at the University of Oxford Botanic Garden said:

'I used to marvel at this extraordinary plant on childhood trips to botanic gardens. I remember wondering how on earth does it grow this big.'

The researchers compared the high-sided giant Amazonian waterlily leaf which has thick veins to Nymphaea – a smaller relation with disc-like leaves and a less prominent vascular system. Using in-situ experiments and mathematical modelling, the team found that the giant Amazonian waterlily leaves had a greater rigidity for a given volume of plant matter.

New study unlocks mystery origin of iconic Aussie snakes

Tiger Snake (Notechis scutatus)
Credit: Max Tibby- Snake Catchers Adelaide

New research led by the University of Adelaide has found the first tangible evidence that the ancestors of some of Australia’s most venomous snakes arrived by sea rather than by land – the dispersal route of most other Australian reptiles.

In a paper published in Genes, the researchers analyzed the genomes of two Australian elapids (front fanged snakes), a tiger and a brown snake, and compared them to marine and semi-marine elapid sea snakes and Asian elapids.

“Some believe their ancestors travelled by land, whereas others hold the more contentious view that a marine or semi-marine ancestor swam here."

Professor David Adelson

They inferred that the ancestor of all Australian elapids had accumulated self-replicating and self-mobilizing genes (jumping genes) that were not present in their land relatives but came from another source altogether.

Einstein’s photoelectric effect: The time it takes for an electron to be released

COLTRIMS reaction microscope at electron storage ring BESSY II, Helmholtz-Zentrum Berlin für Materialien und Energie (HZB).
Photo: Miriam Weller, Goethe University Frankfurt

When light hits a material, electrons can be released from this material – the photoelectric effect. Although this effect played a major role in the development of quantum theory, it still holds a number of secrets: To date it has not been clear how quickly the electron is released after the photon is absorbed. Jonas Rist, a Ph.D. student working within an international team of researchers at the Institute for Nuclear Physics at Goethe University Frankfurt, has now been able to find an answer to this mystery with the aid of a COLTRIMS reaction microscope which had been developed in Frankfurt: The emission takes place lightning fast, namely within just a few attoseconds – within a billionth of billionths of a second.

It is now exactly one hundred years ago that Albert Einstein was awarded the Nobel Prize in Physics for his work on the photoelectric effect. The jury had not yet really understood his revolutionary theory of relativity – but Einstein had also conducted ground-breaking work on the photoelectric effect. With his analysis he was able to demonstrate that light comprises individual packets of energy – so-called photons. This was the decisive confirmation of Max Planck's hypothesis that light is made up of quanta, and paved the way for the modern quantum theory.

Researchers identify brain region associated with feeling full after eating

Feeling full, or satiated, after a meal is healthy and normal, but what causes that feeling is complicated and not well understood. New University of Arizona-led research published in the journal Molecular Metabolism has identified a brain region and neural circuitry that mediate satiation, which could help scientists better target drugs to treat eating disorders or manage weight.

There are currently six Food and Drug Administration-approved medications for weight management, but they often come with side effects.

"When we can more precisely target the part of the brain responsible for feelings of satiation, then we can create treatments with fewer side effects," said lead study author Haijiang Cai, an associate professor in the Department of Neuroscience.

Previous research has mapped the circuits for satiation to the brain's central amygdala, which also controls fear, pain and other strong emotions. But the complexity of the neurons in this part of the brain has made it difficult for scientists to map where the signal goes next.

Cai and his team found that after the amygdala, the signal heads to neurons located in a brain region called the parasubthalamic nucleus, or PSTh, responsible for the feeling of satiation.

Here's how they did it: First, they knew that the hormone cholecystokinin, or CCK, is secreted by the gut to tell the brain "I'm full" after a meal. They also knew that specific neurons in the amygdala, called PKC-delta neurons, mediate the satiation effect of CCK by turning off other central amygdala inhibitory neurons. The researchers reasoned that the neurons downstream of the central amygdala should be turned on by PCK-delta neurons while also being turned on by CCK, Cai said.

Notches on lions’ teeth reveal poaching in Zambia’s conservation areas

UCLA biologist Paula White displays two leopard skulls.
Credit: Paula White

In a hunting camp in Zambia more than a decade ago, UCLA biologist Paula White puzzled over the heavy skull of a trophy-hunted lion. Zambia permits limited hunting in certain areas to help fund its national conservation program, and White had gained permission to examine the trophy skulls and hides to evaluate how hunting was affecting conservation efforts.

This particular skull had a pronounced horizontal V-shaped notch on one of the canine teeth — a marking White had never seen before from natural wear. Over the next few months, she began noticing similar notches on other lions’ teeth.

It wasn’t until three years later, when she visited lions bred in captivity and saw them gnawing on a wire fence, that it clicked: The tooth notches in wild lions resulted from the animals chewing their way out of wire snares — noose-like traps set by poachers. The sheer number of notched teeth she’d seen suggested that such traps, illegal in conservation areas, were injuring far more lions than experts had estimated.

“It was an odd mix of thrilling to figure out the cause of the notches and horrifying to realize that so many animals had been entangled in a snare at some point in their lives,” said White, director of the Zambia Lion Project and a senior research fellow with the Center for Tropical Research at UCLA’s Institute of the Environment and Sustainability.

Earth's Inner Core: A Mixture of Solid Fe and Liquid-like Light Elements

Earth's interior structure and superionic inner core
Image by IGCAS

Earth's core, the deepest part of our planet, is characterized by extremely high pressure and temperature. It is composed of a liquid outer core and solid inner core.

The inner core is formed and grows due to the solidification of liquid iron at the inner core boundary. The inner core is less dense than pure iron, and some light elements are believed to be present in the inner core.

A joint research team of Prof. LI Heping and Prof. HE Yu from the Institute of Geochemistry of the Chinese Academy of Sciences (IGCAS) and Prof. MAO Ho-kwang and Prof. KIM Duck Young from Center for High Pressure Science & Technology Advanced Research (HPSTAR) has found that the inner core of the Earth is not a normal solid but is composed of a solid iron sublattice and liquid-like light elements, which is also known as a superionic state. The liquid-like light elements are highly diffusive in iron sublattices under inner core conditions.

This study was published in Nature on Feb. 9.

A superionic state, which is an intermediate state between solid and liquid, widely exists in the interior of planets. Using high-pressure and high-temperature computational simulations based on quantum mechanics theory, researchers from IGCAS and the Center for High Pressure Science & Technology Advanced Research (HPSTAR) found that some Fe-H, Fe-C and Fe-O alloys transformed into a superionic state under inner core conditions.

In superionic iron alloys, light elements become disordered and diffuse like a liquid in the lattice, while iron atoms remain ordered and vibrate about their lattice grid, forming the solid iron framework. The diffusion coefficients of C, H and O in superionic iron alloys are the same as those in liquid Fe.

"It is quite abnormal. The solidification of iron at the inner core boundary does not change the mobility of these light elements, and the convection of light elements is continuous in the inner core," said Prof. HE Yu, the first and corresponding author of the study.

A new approach for detecting ultra-low-energy photons

A low energy photon emitted by a qubit can potentially be detected by measuring its energy with two thermometers simultaneously. The two signals are combined into a cross-correlation measurement with superior sensitivity.
Illustration: Bayan Karimi.

Professor Jukka Pekola and Doctoral Candidate Bayan Karimi from Aalto University propose a new approach to measure the energy of single microwave photons. These low energy quanta are emitted by artificial quantum systems such as superconducting qubits. Detecting them continuously has been challenging but would be useful in quantum information processing and other quantum technologies.

A photon is produced when a superconducting qubit transits between states, radiating energy into its environment. The researchers capture the tiny energy of this photon by transferring it into heat. The new technique relies on splitting the energy of a photon across two independent heat baths and making measurements using two uncoupled detectors at once. This would significantly enhance the signal-to-noise ratio, making it easier to detect an absorption event and its energy.

‘In our proposed setup the energy of a qubit is large whereas its typical operating temperature is very low. This contrast opened an opportunity to solve the Schrödinger equation exactly for up to one million external oscillators forming the heat baths in the model describing this measurement,’ Pekola says.

Fossils excavated in the 1960s add missing link to crocodile evolution

Credit: Gabriel Ugueto

A set of Triassic archosaur fossils, excavated in the 1960s in Tanzania, have been formally recognized as a distinct species, representing one of the earliest-known members of the crocodile evolutionary lineage.

Researchers at the University of Birmingham, the Natural History Museum and Virginia Tech University have named the animal Mambawakale ruhuhu. It is among the last to be studied of a collection of fossils dug up nearly 60 years ago from the Manda Beds, a geological formation in southern Tanzania.

The remains, which are the only known example of Mambawakale ruhuhu, include a partial skull, lower jaw, several vertebrae and a hand. From these, the research team were able to identify several distinctive features that set it apart from other archosaurs found in the Manda Beds.

These included a large skull, more than 75 cm in length, and a particularly large nostril, as well as a notably narrow lower jaw and strong variation in the sizes of the teeth at the front of the upper jaws.

A catalyst that can turn carbon dioxide into gasoline 1,000 times more efficiently

Chengshuang Zhou holds vials of ruthenium, left, and the coated catalyst, while Matteo Cargnello holds the pipe used for the reaction experiments.
Image credit: Mark Golden

Captured CO2 can be turned into carbon-neutral fuels, but technological advances are needed. In new research, a new catalyst increased the production of long-chain hydrocarbons in chemical reactions by some 1,000 times over existing methods.

Engineers working to reverse the proliferation of greenhouse gases know that in addition to reducing carbon dioxide emissions we will also need to remove carbon dioxide from power plant fumes or from the skies. But, what do we do with all that captured carbon? Matteo Cargnello, a chemical engineer at Stanford University, is working to turn it into other useful chemicals, such as propane, butane or other hydrocarbon fuels that are made up of long chains of carbon and hydrogen.

“We can create gasoline, basically,” said Cargnello, who is an assistant professor of chemical engineering. “To capture as much carbon as possible, you want the longest chain hydrocarbons. Chains with eight to 12 carbon atoms would be the ideal.”

A new catalyst, invented by Cargnello and colleagues, moves toward this goal by increasing the production of long-chain hydrocarbons in chemical reactions. It produced 1,000 times more butane – the longest hydrocarbon it could produce under its maximum pressure – than the standard catalyst given the same amounts of carbon dioxide, hydrogen, catalyst, pressure, heat and time. The new catalyst is composed of the element ruthenium – a rare transition metal belonging to the platinum group – coated in a thin layer of plastic. Like any catalyst, this invention speeds up chemical reactions without getting used up in the process. Ruthenium also has the advantage of being less expensive than other high-quality catalysts, like palladium and platinum.

'Molecular Velcro' enables tissues to sense, react to mechanical force

University of Illinois professor Deborah Leckband led a study that revealed how Velcro-like cellular proteins called cadherins sense tissue mechanics to regulate cell communication and biological tissue growth. 
Photo courtesy Claire Benjamin

The Velcro-like cellular proteins that hold cells and tissues together also perform critical functions when they experience increased tension. A new University of Illinois Urbana-Champaign study observed that when tugged upon in a controlled manner, these proteins – called cadherins – communicate with growth factors to influence in vitro tumor growth in human carcinoma cells.

The study, led by chemical and biomolecular engineering professor Deborah Leckband, found that cadherins that bond with growth factor receptors can sense mechanical force and respond by altering cell communication and growth.

The findings are published in the Proceedings of the National Academy of Sciences.

When bound to cadherin molecules in normal tissue, growth factor receptors cannot communicate with growth factor proteins – the substance they need to promote tissue growth. However, the study shows that changes in tensional stress on cadherin bonds disrupt the cadherin-growth factor interaction to switch on growth signals in tissues.