Although hydrovoltaic devices currently exist, there is very little functional understanding of the conditions and physical phenomena that govern HV energy production at the nanoscale. It’s an information gap that Giulia Tagliabue, head of the Laboratory of Nanoscience for Energy Technology (LNET) in the School of Engineering, and PhD student Tarique Anwar wanted to fill. They leveraged a combination of experiments and multiphysics modelling to characterize fluid flows, ion flows, and electrostatic effects due to solid-liquid interactions, with the goal of optimizing HV devices.

“Thanks to our novel, highly controlled platform, this is the first study that quantifies these hydrovoltaic phenomena by highlighting the significance of various interfacial interactions. But in the process, we also made a major finding: that hydrovoltaic devices can operate over a wide range of salinities, contradicting prior understanding that highly purified water was required for best performance,” says Tagliabue.

The LNET study has recently been published in the Cell Press journal Device.

A revealing multiphysics model

The researchers’ device represents the first hydrovoltaic application of a technique called nanosphere colloidal lithography, which allowed them to create a hexagonal network of precisely spaced silicon nanopillars. The spaces between the nanopillars created the perfect channels for evaporating fluid samples, and could be finely tuned to better understand the effects of fluid confinement and the solid/liquid contact area.

“In most fluidic systems containing saline solutions, you have an equal number of positive and negative ions. However, when you confine the liquid to a nanochannel, only ions with a polarity opposite to that of the surface charge will remain,” Anwar explains. “This means that if you allow liquid to flow through the nanochannel, you will generate current and voltages.”

“This goes back to our major finding that the chemical equilibrium for the surface charge of the nanodevice can be exploited to extend the operation of hydrovoltaic devices across the salinity scale,” adds Tagliabue. “Indeed, as the fluid ion concentration increases, so does the surface charge of the nanodevice. As a result, we can use larger fluid channels while working with higher-concentration fluids. This makes it easier to fabricate devices for use with tap or seawater, as opposed to only purified water.”

Water, water everywhere

Because evaporation can occur continuously over a wide range of temperatures and humidities — and even at night — there are many exciting potential applications for more efficient HV devices. The researchers hope to explore this potential with the support of a Swiss National Science Foundation Starting Grant, which aims to develop “a completely new paradigm for waste-heat recovery and renewable energy generation at large and small scales,” including a prototype module under real-world conditions on Lake Geneva.

And because HV devices could theoretically be operated anywhere there is liquid — or even moisture, like sweat — they could also be used to power sensors for connected devices, from smart TVs to health and fitness wearables. With the LNET’s expertise in light energy harvesting and storage systems, Tagliabue is also keen to see how light and photothermal effects could be used to control surface charges and evaporation rates in HV systems.

Finally, the researchers also see important synergies between HV systems and clean water generation.

“Natural evaporation is used to drive desalination processes, as fresh water can be harvested from saltwater by condensing the vapor produced by an evaporative surface. Now, you could imagine using an HV system both to produce clean water and harness electricity at the same time,” Anwar explains.

Using the James Webb Space Telescope, an international team of astronomers led by the University of Cambridge have spotted a ‘dead’ galaxy when the universe was just 700 million years old, the oldest such galaxy ever observed.

This galaxy appears to have lived fast and died young: star formation happened quickly and stopped almost as quickly, which is unexpected for so early in the universe’s evolution. However, it is unclear whether this galaxy’s ‘quenched’ state is temporary or permanent, and what caused it to stop forming new stars.

The results, reported in the journal Nature, could be important to help astronomers understand how and why galaxies stop forming new stars, and whether the factors affecting star formation have changed over billions of years.

“The first few hundred million years of the universe was a very active phase, with lots of gas clouds collapsing to form new stars,” said Tobias Looser from the Kavli Institute for Cosmology, the paper’s first author. “Galaxies need a rich supply of gas to form new stars, and the early universe was like an all-you-can-eat buffet.”

“It’s only later in the universe that we start to see galaxies stop forming stars, whether that’s due to a black hole or something else,” said co-author Dr Francesco D’Eugenio, also from the Kavli Institute for Cosmology.

Astronomers believe that star formation can be slowed or stopped by different factors, all of which will starve a galaxy of the gas it needs to form new stars. Internal factors, such as a supermassive black hole or feedback from star formation, can push gas out of the galaxy, causing star formation to stop rapidly. Alternatively, gas can be consumed very quickly by star formation, without being promptly replenished by fresh gas from the surroundings of the galaxy, resulting in galaxy starvation.

“We’re not sure if any of those scenarios can explain what we’ve now seen with Webb,” said co-author Professor Roberto Maiolino. “Until now, to understand the early universe, we’ve used models based on the modern universe. But now that we can see so much further back in time, and observe that the star formation was quenched so rapidly in this galaxy, models based on the modern universe may need to be revisited.”

Using data from JADES (JWST Advanced Deep Extragalactic Survey), the astronomers determined that this galaxy experienced a short and intense period of star formation over a period between 30 and 90 million years. But between 10 and 20 million years before the point in time where it was observed with Webb, star formation suddenly stopped.

“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” said Looser.

Astronomers have previously observed dead galaxies in the early universe, but this galaxy is the oldest yet — just 700 million years after the big bang, more than 13 billion years ago. This observation is one of the deepest yet made with Webb.

In addition to the oldest, this galaxy is also relatively low mass — about the same as the Small Magellanic Cloud (SMC), a dwarf galaxy near the Milky Way, although the SMC is still forming new stars. Other quenched galaxies in the early universe have been far more massive, but Webb’s improved sensitivity allows smaller and fainter galaxies to be observed and analysed.

The astronomers say that although it appears dead at the time of observation, it’s possible that in the roughly 13 billion years since, this galaxy may have come back to life and started forming new stars again.

“We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” said D’Eugenio. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life — we’ll need more observations to help us figure that out.”

The research was supported in part by the European Research Council, the Royal Society, and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

In a study published in Nature, the team describes how they analyzed gene expression in more than a million individual cells from postmortem brain tissue from 191 people. They found that in individuals with schizophrenia and in older adults without schizophrenia, two brain cell types called astrocytes and neurons reduced their expression of genes that support the junctions between neurons called synapses, compared to healthy or younger people. They also discovered tightly synchronized gene expression changes in the two cell types: when neurons decreased the expression of certain genes related to synapses, astrocytes similarly changed expression of a distinct set of genes that support synapses.

The team called this coordinated set of changes the Synaptic Neuron and Astrocyte Program (SNAP). Even in healthy, young people, the expression of the SNAP genes always increased or decreased in a coordinated way in their neurons and astrocytes.

“Science often focuses on what genes each cell type expresses on its own,” said Steve McCarroll, a co-senior author on the study and an institute member at the Broad Institute. “But brain tissue from many people, and machine-learning analyses of those data, helped us recognize a larger system. These cell types are not acting as independent entities, but have really close coordination. The strength of those relationships took our breath away.”

Schizophrenia is well-known for causing hallucinations and delusion, which can be at least partly treated with medications. But it also causes debilitating cognitive decline, which has no effective treatments and is common in aging as well. The new findings suggest that the cognitive changes in both conditions might involve similar cellular and molecular alterations in the brain.

“To detect coordination between astrocytes and neurons in schizophrenia and aging, we needed to study tissue samples from a very large number of individuals,” said Sabina Berretta, a co-senior author of the study, an associate professor at Harvard Medical School, and a researcher in the field of psychiatric disorders. “Our gratitude goes to all donors who chose to donate their brain to research to help others suffering from brain disorders and to whom we’d like to dedicate this work.”

McCarroll is also director of genomic neurobiology for the Broad’s Stanley Center for Psychiatric Research and a professor at Harvard Medical School. Berretta also directs the Harvard Brain Tissue Resource Center (HBTRC), which provided tissue for the study. Emi Ling, a postdoctoral researcher in McCarroll’s lab, was the study’s first author.

SNAP insights

The brain works in large part because neurons connect with other neurons at synapses, where they pass signals to one another. The brain constantly forms new synapses and prunes old ones. Scientists think new synapses help our brains stay flexible, and studies — including previous efforts by scientists in McCarroll’s lab and international consortia — have shown that many genetic factors linked to schizophrenia involve genes that contribute to the function of synapses.

In the new study, McCarroll, Berretta, and colleagues used single-nucleus RNA sequencing, which measures gene expression in individual cells, to better understand how the brain naturally varies across individuals. They analyzed 1.2 million cells from94 people with schizophrenia and 97 without.

They found that when neurons boosted expression of genes that encode parts of synapses, astrocytes increased the expression of a distinct set of genes involved in synaptic function. These genes, which make up the SNAP program, included many previously identified risk factors for schizophrenia. The team’s analyses indicated that both neurons and astrocytes shape genetic vulnerability for the condition.

“Science has long known that neurons and synapses are important in risk for schizophrenia, but by framing the question a different way — asking what genes each cell type regulates dynamically — we found that astrocytes too are likely involved,” said Ling.

To their surprise, the researchers also found that SNAP varied greatly even among people without schizophrenia, suggesting that SNAP could be involved in cognitive differences in healthy humans. Much of this variation was explained by age; SNAP declined substantially in many — but not all — older individuals, including both people with and without schizophrenia.

With better understanding of SNAP, McCarroll says he hopes it might be possible to identify life factors that positively influence SNAP, and develop medicines that help stimulate SNAP, as a way to treat the cognitive impairments of schizophrenia or help people maintain their cognitive flexibility as they age.

In the meantime, McCarroll, Berretta, and their team are working to understand if these changes are present in other conditions such as bipolar disorder and depression. They also aim to uncover the extent to which SNAP appears in other brain areas, and how SNAP affects learning and cognitive flexibility.

Funding:

This work was supported by the Stanley Family Foundation, the Simons Collaboration on Plasticity and the Aging Brain, and the National Institute of Mental Health and the National Human Genome Research Institute at the National Institutes of Health.

Anyone who has used a microscope in a biology class to study a plant cell will probably be able to recall a similar situation. It is easy to tell that a certain chloroplast is located above and to the right of the nucleus. But are both of them located on the same plane? Once you adjust the focus on the microscope, however, you see that the image of the nucleus becomes sharper while the image of the chloroplast blurs. One of them must be a little higher and one a little lower than the other. However, this method cannot give us precise details about their vertical positions.

The principle is very similar if you want to observe individual atoms instead of cells. So-called quantum gas microscopy can be used for this purpose. It allows you to straightforwardly determine the x and y coordinates of an atom. However, it is much more difficult to measure its z coordinate, i.e., the distance to the objective lens: In order to find out on what plane the atom is located, multiple images must be taken in which the focus is shifted across various different planes. This is a complex and time-consuming process.

Turning round specks into dumbbells

“We have now developed a method in which this process can be completed in one step,” explains Tangi Legrand from the Institute of Applied Physics (IAP) at the University of Bonn. “To achieve this, we use an effect that has already been known in theory since the 1990s but which had not yet been used in a quantum gas microscope.”

To experiment on the atoms, it is first necessary to cool them down significantly so that they are barely moving. Afterwards, it is possible, for example, to trap them in a standing wave of laser light. They then slip into the troughs of the wave similar to how eggs sit in an egg box. Once trapped, to reveal their position, they are exposed to an additional laser beam, which stimulates them to emit light. The resulting fluorescence shows up in the quantum gas microscope as a slightly blurred, round speck.

“We have now developed a special method to deform the wavefront of the light being emitted by the atom,” explains Dr. Andrea Alberti. The researcher, who has now moved from the IAP to the Max Planck Institute of Quantum Optics in Garching, also participated in the study. “Instead of the typical round specks, the deformed wavefront produces a dumbbell shape on the camera that rotates around itself. The direction in which this dumbbell points is dependent on the distance that the light had to travel from the atom to the camera.”

“The dumbbell thus acts a bit like the needle on a compass, allowing us to read off the z coordinate according to its orientation,” says Prof. Dr. Dieter Meschede. The IAP researcher, whose research group carried out the study, is also a member of the transdisciplinary research area “Matter” at the University of Bonn.

Important for quantum mechanics experiments

The new method makes it possible to precisely determine the position of an atom in three dimensions with one single image. This is important, for example, if you want to carry out quantum mechanics experiments with atoms because it is often essential to be able to precisely control or track their position. This allows researchers to make the atoms interact with one another in the desired way.

Furthermore, the method could also be used to help develop new quantum materials with special characteristics. “For example, we could investigate which quantum mechanical effects occur when atoms are arranged in a certain order,” explains Dr. Carrie Weidner from the University of Bristol. “This would allow us to simulate the properties of three-dimensional materials to some extent without having to synthesize them.”

The study, led by Professor Jun Suzuki of the Institute for Integrated Cell-Material Sciences (iCeMS), addresses a critical gap by directly targeting genes within testicular cells inside living organisms. Utilizing a genetic tool called CRISPR, which can be likened to genetic scissors, the researchers developed a method to investigate which genes contribute to healthy sperm production in living animals. Until now, this had mainly been done in cells cultivated in the laboratory. The researchers randomly disrupted genes by developing a method to introduce a collection of genetic tools in lentivirus into testicular cells in testes at high efficiency. Through this method, the researchers made it possible to analyze the effects of targeted genes on specific biochemical reactions in the sperm cells, such as the movement of lipids (fats) in cell membranes.

Using the method, the team focused on sperms with defective capacitation, a process through which sperms become capable of fertilizing an egg. They identified these sperms by measuring how much calcium they absorbed. By using this method in live animals, they were able to identify a specific gene, Rd3, as being crucial for maintaining sperm cell health, particularly during sperm cell development. Despite Rd3’s previous association with eye function, the team found it is also highly active in round sperm cells, an early stage in sperm production, and that it plays a significant role in regulating sperm health. This discovery was made possible by examining how Rd3 interacts with mitochondria, structures responsible for energy production within cells.

To further understand Rd3’s function, Suzuki and his colleagues developed Hub-Explorer, a computational tool that revealed Rd3’s impact on regulation of oxidative stress — a condition linked to cellular damage. Rd3’s role in regulating oxidative stress revealed its significance in maintaining sperm integrity during development.

“While women have many available birth control options, choices for men remain limited,” says Noguchi, a first author of this paper. “This new screening method holds promise by aiding the discovery of key molecules, potentially leading to new birth control options and infertility therapies for men.”

“These discoveries not only advance our understanding of sperm cell development but also demonstrate the potential to uncover mysteries in different biological processes,” adds Suzuki. “The method can also be applied to other tissues, potentially expediting the development of drugs for a wide range of diseases.”

Despite these advancements, challenges remain. The researchers observed a gradual decline in the number of cells with targeted genes, suggesting room for improvement. They are currently exploring alternative approaches to enhance the effectiveness of their technique, and they plan to apply it to investigate various biological processes and diseases in other areas of the body.

Findings of the study led by Gaurav Sahay and Yulia Eygeris of the Oregon State University College of Pharmacy and Renee Ryals of Oregon Health & Science University were published today in the Proceedings of the National Academy of Sciences.

Unlike other types of lipid nanoparticles that tend to accumulate in the liver, the ones in this study, based on the compound thiophene, are able to navigate their way to the tissues of the lungs and retina, where they deliver their therapeutic payload. The researchers refer to these new lipids as Thio-lipids.

The collaboration demonstrated, by using animal models, the possibility of using Thio-lipids in lipid nanoparticles to deliver messenger RNA, the technology underpinning COVID-19 vaccines, to combat genetic blindness and pulmonary disease.

“These nanoparticles filled with fatty lipids can encapsulate genetic medicines like mRNA and CRISPR-Cas9 gene editors, which can be used to treat and even cure rare genetic diseases,” said Eygeris, a senior research associate at OSU. “Chemical structures of the lipids determine how potent are the lipid nanoparticles and which organ they can reach from the bloodstream.”

Lipids are organic compounds containing fatty tails and are found in many natural oils and waxes, and nanoparticles are tiny pieces of material ranging in size from one- to 100-billionths of a meter. Messenger RNA delivers instructions to cells for making a particular protein.

With the coronavirus vaccines, the mRNA carried by the lipid nanoparticles instructs cells to make a harmless piece of the virus’ spike protein, which triggers an immune response from the body.

As a therapy for vision impairment resulting from inherited retinal degeneration, the mRNA would instruct cells in the retina — which don’t work right because of a genetic mutation — to manufacture the proteins needed for sight. Inherited retinal degeneration, commonly abbreviated to IRD, encompasses a group of disorders of varying severity and prevalence that affect one out of every few thousand people worldwide.

An example of a genetic pulmonary condition is cystic fibrosis, a progressive disorder that results in persistent lung infection and affects 30,000 people in the U.S., with about 1,000 new cases identified every year.

One faulty gene — the cystic fibrosis transmembrane conductance regulator, or CFTR — causes the disease, which is characterized by lung dehydration and mucus buildup that blocks the airway.

The thiophene-based lipid nanoparticle study, which involved mice and non-human primates, stems from a $3.2 million grant to Sahay and Ryals from the National Eye Institute. The grant’s purpose is addressing limitations associated with the current primary means of delivery for gene editing: a type of virus known as adeno-associated virus, or AAV.

“AAV has limited packaging capacity compared to lipid nanoparticles and it can prompt an immune system response,” said Sahay, a professor of pharmaceutical sciences. “It also doesn’t do fantastically well in continuing to express the enzymes the editing tool uses as molecular scissors to make cuts in the DNA to be edited.”

Sahay calls the Thio-lipid findings “highly encouraging” but says more studies are needed, including research on the lipids’ long-term impact on retinal health.

“But we think our results serve as a proof of concept and we will continue to explore Thio-lipids in potential treatments of pulmonary and retinal genetic diseases,” he said.

In addition to the National Eye Institute, funding and research support were provided by the Oregon National Primate Research Center and the Casey Eye Institute.