Mysterious Neptune dark spot detected from Earth for the first time

 Using ESO's Very Large Telescope (VLT), astronomers have observed a large dark spot in Neptune's atmosphere, with an unexpected smaller bright spot adjacent to it. This is the first time a dark spot on the planet has ever been observed with a telescope on Earth. These occasional features in the blue background of Neptune's atmosphere are a mystery to astronomers, and the new results provide further clues as to their nature and origin.

Large spots are common features in the atmospheres of giant planets, the most famous being Jupiter's Great Red Spot. On Neptune, a dark spot was first discovered by NASA's Voyager 2 in 1989, before disappearing a few years later. "Since the first discovery of a dark spot, I've always wondered what these short-lived and elusive dark features are," says Patrick Irwin, Professor at the University of Oxford in the UK and lead investigator of the study published today in Nature Astronomy.

Irwin and his team used data from ESO's VLT to rule out the possibility that dark spots are caused by a 'clearing' in the clouds. The new observations indicate instead that dark spots are likely the result of air particles darkening in a layer below the main visible haze layer, as ices and hazes mix in Neptune's atmosphere.

Coming to this conclusion was no easy feat because dark spots are not permanent features of Neptune's atmosphere and astronomers had never before been able to study them in sufficient detail. The opportunity came after the NASA/ESA Hubble Space Telescope discovered several dark spots in Neptune's atmosphere, including one in the planet's northern hemisphere first noticed in 2018. Irwin and his team immediately got to work studying it from the ground -- with an instrument that is ideally suited to these challenging observations.

Using the VLT's Multi Unit Spectroscopic Explorer (MUSE), the researchers were able to split reflected sunlight from Neptune and its spot into its component colours, or wavelengths, and obtain a 3D spectrum [1]. This meant they could study the spot in more detail than was possible before. "I'm absolutely thrilled to have been able to not only make the first detection of a dark spot from the ground, but also record for the very first time a reflection spectrum of such a feature," says Irwin.

Since different wavelengths probe different depths in Neptune's atmosphere, having a spectrum enabled astronomers to better determine the height at which the dark spot sits in the planet's atmosphere. The spectrum also provided information on the chemical composition of the different layers of the atmosphere, which gave the team clues as to why the spot appeared dark.

The observations also offered up a surprise result. "In the process we discovered a rare deep bright cloud type that had never been identified before, even from space," says study co-author Michael Wong, a researcher at the University of California, Berkeley, USA. This rare cloud type appeared as a bright spot right beside the larger main dark spot, the VLT data showing that the new 'deep bright cloud' was at the same level in the atmosphere as the main dark spot. This means it is a completely new type of feature compared to the small 'companion' clouds of high-altitude methane ice that have been previously observed.

With the help of ESO's VLT, it is now possible for astronomers to study features like these spots from Earth. "This is an astounding increase in humanity's ability to observe the cosmos. At first, we could only detect these spots by sending a spacecraft there, like Voyager. Then we gained the ability to make them out remotely with Hubble. Finally, technology has advanced to enable this from the ground," concludes Wong, before adding, jokingly: "This could put me out of work as a Hubble observer!"

Note

[1] MUSE is a 3D spectrograph that allows astronomers to observe the entirety of an astronomical object, like Neptune, in one go. At each pixel, the instrument measures the intensity of light as a function of its colour or wavelength. The resulting data form a 3D set in which each pixel of the image has a full spectrum of light. In total, MUSE measures over 3500 colours. The instrument is designed to take advantage of adaptive optics, which corrects for the turbulence in the Earth's atmosphere, resulting in sharper images than otherwise possible. Without this combination of features, studying a Neptune dark spot from the ground would not have been possible.

New study finds ways to suppress lithium plating in automotive batteries for faster charging electric vehicles

 A new study led by Dr. Xuekun Lu from Queen Mary University of London in collaboration with an international team of researchers from the UK and USA has found a way to prevent lithium plating in electric vehicle batteries, which could lead to faster charging times. The paper was published in the journal Nature Communications.

Lithium plating is a phenomenon that can occur in lithium-ion batteries during fast charging. It occurs when lithium ions build up on the surface of the battery's negative electrode instead of intercalating into it, forming a layer of metallic lithium that continues growing. This can damage the battery, shorten its lifespan, and cause short-circuits that can lead to fire and explosion.

Dr. Xuekun Lu explains that lithium plating can be significantly mitigated by optimizing the microstructure of the graphite negative electrode. The graphite negative electrode is made up of randomly distributed tiny particles, and fine-tuning the particle and electrode morphology for a homogeneous reaction activity and reduced local lithium saturation is the key to suppress lithium plating and improve the battery's performance.

"Our research has revealed that the lithiation mechanisms of graphite particles vary under distinct conditions, depending on their surface morphology, size, shape and orientation. It largely affects the lithium distribution and the propensity of lithium plating," said Dr. Lu. "Assisted by a pioneering 3D battery model, we can capture when and where lithium plating initiates and how fast it grows. This is a significant breakthrough that could have a major impact on the future of electric vehicles."

The study provides new insights into developing advanced fast charging protocols by improving the understanding of the physical processes of lithium redistribution within graphite particles during fast charging. This knowledge could lead to an efficient charging process while minimising the risk of lithium plating.

In addition to faster charging times, the study also found that refining the microstructure of the graphite electrode can improve the battery's energy density. This means that electric cars could travel further on a single charge.

These findings are a major breakthrough in the development of electric vehicle batteries. They could lead to faster-charging, longer-lasting, and safer electric cars, which would make them a more attractive option for consumers.

Light regulates structural conversion of chiral molecules

 Just like our hands, certain organic molecules relate to each other like an image and its reflection -- a phenomenon that chemists call "chirality" or "handedness." The two mirror images of the same molecule, namely both enantiomers, often possess different biological properties. For example for drug discovery, many times only one of the structures is relevant. However, chemical synthesis methods often create a 1:1 mixture of both forms. Therefore, the selective conversion of these mixtures into one selected form is of great importance.

A team of researchers from the Institute of Organic Chemistry and from the Center for Multiscale Theory and Computation at the University of Münster led by Prof. Ryan Gilmour and Prof. Johannes Neugebauer developed a novel concept in which this conversion is enabled by light as an external energy source. The study is now published in the journal Nature.

The researchers apply an aluminium complex, that is activated by light, as catalyst to selectively convert a mixture of molecules that behave like mirror images to a single form. The reaction process was investigated experimentally and computationally. The detailed computer-based analyses contributed significantly to the understanding of the underlying processes. The new paradigm impresses with its operational simplicity and broad applicability, as the aluminium complex used is a common catalyst for chemical reactions driven by heat. Translation to light-mediated processes is now envisaged to enable a plethora of new reactivities with great spatial control.

Achieving spatial control in light-mediated reactions is one of the main challenges in contemporary organic chemistry. To this end, usually two distinct catalysts are employed in one reaction: a photocatalyst, that initiates the reactivity, operates in concert with a second catalyst that controls the spatial arrangement of the molecules. Contrarily, the successful integration of both functions in a single catalyst structure was so far only achieved by incorporation of tailored recognition motifs in the catalyst and substrate structures. In this work, the groups present a catalyst that regulates reactivity and selectivity simultaneously. It binds to simple ketones, a functional group that is prevalent in organic molecules, circumventing the need for tailored components. Furthermore, the catalyst is based on earth-abundant aluminium, which is cheaper that the transition metals that are commonly found in photocatalysts.

Scientists invent micrometers-thin battery charged by saline solution that could power smart contact lenses

 Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a flexible battery as thin as a human cornea, which stores electricity when it is immersed in saline solution, and which could one day power smart contact lenses.

Smart contact lenses are high-tech contact lenses capable of displaying visible information on our corneas and can be used to access augmented reality. Current uses include helping to correct vision, monitoring wearers' health, and flagging and treating diseases for people with chronic health conditions such as diabetes and glaucoma. In the future, smart contact lenses could be developed to record and transmit everything a wearer sees and hears to cloud-based data storage.

However, to reach this future potential a safe and suitable battery needs to be developed to power them. Existing rechargeable batteries rely on wires or induction coils that contain metal and are unsuitable for use in the human eye, as they are uncomfortable and present risks to the user.

The NTU-developed battery is made of biocompatible materials and does not contain wires or toxic heavy metals, such as those in lithium-ion batteries or wireless charging systems. It has a glucose-based coating that reacts with the sodium and chloride ions in the saline solution surrounding it, while the water the battery contains serves as the 'wire' or 'circuitry' for electricity to be generated.

The battery could also be powered by human tears as they contain sodium and potassium ions, at a lower concentration. Testing the current battery with a simulated tear solution, the researchers showed that the battery's life would be extended an additional hour for every twelve-hour wearing cycle it is used. The battery can also be charged conventionally by an external power supply.

Associate Professor Lee Seok Woo, from NTU's School of Electrical and Electronic Engineering (EEE), who led the study, said: "This research began with a simple question: could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.

"However, previous techniques for lens batteries were not perfect as one side of the battery electrode was charged and the other was not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction. Besides the charging mechanism, it relies on just glucose and water to generate electricity, both of which are safe to humans and would be less harmful to the environment when disposed, compared to conventional batteries."

Co-first author Dr Yun Jeonghun, a research fellow from NTU's EEE said: "The most common battery charging system for smart contact lenses requires metal electrodes in the lens, which are harmful if they are exposed to the naked human eye. Meanwhile, another mode of powering lenses, induction charging, requires a coil to be in the lens to transmit power, much like wireless charging pad for a smartphone. Our tear-based battery eliminates the two potential concerns that these two methods pose, while also freeing up space for further innovation in the development smart contact lenses."

Highlighting the significance of the work done by the research team, NTU School of Mechanical & Aerospace Engineering Associate Professor Murukeshan Vadakke Matham, who specialises in biomedical and nanoscale optics and was not involved in the study, said: "As this battery is based on glucose oxidase, which occurs naturally in humans and powered by chloride and sodium ions, such as those in our tears, they should be compatible and suitable for human usage. Besides that, the smart contact lenses industry has been looking for a thin, biocompatible battery that does not contain heavy metals, and this invention could help further their development to meet some unmet needs of the industry."

The research team has filed for a patent through NTUitive, NTU's innovation and enterprise company. They are also working towards commercialising their invention.

The findings were published in the scientific journal Nano Energy in June.

Cry me a current

The team demonstrated their invention using a simulated human eye. The battery, which is about 0.5 millimetres-thin generates electrical power by reacting with the basal tears -- the constant tears that create a thin film over our eyeballs -- for the devices embedded within the lenses to function.

The flexible and flat battery discharges electricity through a process called reduction when its glucose oxidase coating reacts with the sodium and chloride ions in the tears, generating power and current within the contact lenses.

The team demonstrated that the battery could produce a current of 45 microamperes and a maximum power of 201 microwatts, which would be sufficient to power a smart contact lens.

Laboratory tests showed that the battery could be charged and discharged up to 200 times. Typical lithium-ion batteries have a lifespan of 300 to 500 charging cycles.

The team recommends that the battery should be placed for at least eight hours in a suitable solution that contains a high quantity of glucose, sodium and potassium ions, to be charged while the user is asleep.

Co-first author Miss Li Zongkang, a PhD student from NTU's EEE said: "Although wireless power transmission and supercapacitors supply high power, their integration presents a significant challenge due to the limited amount of space in the lens. By combining the battery and biofuel cell into a single component, the battery can charge itself without the need for additional space for wired or wireless components. Furthermore, the electrodes placed at the outer side of the contact lens ensures that the vision of the eye cannot be obstructed."

Researchers describe rebuilding, regenerating lung cells

 Researchers from the Center for Regenerative Medicine (CReM), a joint venture between Boston University and Boston Medical Center, have discovered a novel approach for engrafting engineered cells into injured lung tissue. These findings may lead to new ways for treating lung diseases, such as emphysema, pulmonary fibrosis and COVID-19. The two studies describing the methodologies for engineering lung stem cells and transplanting them into injured experimental lungs without immunosuppression appear online in Cell Stem Cell.

For more than 20 years, the scientists leading this work have pursued a way to engraft cells into injured lung tissues with the goal of regenerating lung airways or alveoli. They suspected that for engraftment to be long-lived and functional it would be important to reconstitute the stem or progenitor "compartments" of the lung, also sometimes known as stem cell niches. They concentrated on first developing methods for engineering each of the lung's stem or progenitor cells in the laboratory using pluripotent stem cells, and then developed methods for transplanting these cells into experimental mouse models with injured lungs.

In their study "Airway Stem Cell Reconstitution by Transplantation of Primary or Pluripotent Stem Cell-Derived Basal Cells," the CReM researchers focus on the lung airways. These airways are lined by an epithelium that has well described stem cells called "basal cells," which are responsible for maintaining these airways throughout life.

"By differentiating experimental model and human pluripotent stem cells into airway basal cells in the laboratory dish, we were then able to use these cells to reconstitute the stem cell compartment of the injured model airways in vivo (in living tissue). This resulted in life-long engraftment of the engineered basal cells in an immunocompetent model. Because the cells engrafted as basal cells, the normal stem cell of the airways, they were able to self-renew or make copies of themselves by dividing and also giving rise to other cell types that together make a functional airway epithelium," explained corresponding author Darrell Kotton, MD, the David C. Seldin Professor of Medicine at Boston University Chobanian & Avedisian School of Medicine and director of the CReM.

In their second paper, "Durable alveolar engraftment of PSC-derived lung epithelial cells into immunocompetent mice," CReM researchers targeted the lung air sacks, known as alveoli. Kotton and his team developed methods for engrafting engineered cells into the alveoli, the region of the lung responsible for gas exchange. The engrafted cells formed both types of alveolar cells, called type 1 and type 2 pneumocytes. Since type 2 pneumocytes act as progenitors of lung alveoli throughout life, forming new type 2 pneumocytes out of their transplanted engineered cells ensured the cells would self-renew and differentiate to maintain lung alveoli for a long time.

The researchers believe the reconstitution of lung stem and progenitor cells in the airways and alveoli using cells engineered from pluripotent stem cells is an important finding with many implications for the future treatment of lung diseases that involve injury, degeneration or mutations. "Since induced pluripotent stem cells (iPSCs) can be generated from the blood or skin of any individual through a technology called reprogramming, we hope this work will help to pave the way towards developing new therapeutic approaches where iPSCs can be made from any patient with lung disease, differentiated into lung stem cells in the laboratory, and used for transplantation to reconstitute the healthy airway and alveolar epithelial tissues in a way that is durable and functional," said Martin Ma, first author of the first paper and a BU MD/PhD student in the Kotton lab.

For those suffering from genetic lung diseases, like cystic fibrosis and primary ciliary dyskinesia, it is possible to gene-edit the iPSCs in the laboratory prior to transplantation, meaning the newly engrafted cells will have had their gene mutation corrected and should be free of disease. "Since these cells will be the patient's own cells, differing only in the corrected gene, in theory they should not be rejected after transplantation back into that patient, thus avoiding any need for immunosuppression, as we have demonstrated in our two proof-of-concept syngeneic transplantation studies in immunocompetent experimental models" added Michael Herriges, PhD, first author of the second paper and a postdoctoral fellow in the Kotton lab.

According to Kotton, these papers represent the culmination of 20 years of research. "While treatment of lung diseases like emphysema, pulmonary fibrosis and COVID-19 will take a lot more research, we are hopeful that those with gene mutations that cause damage to lung airways or alveoli, such as children or adults with familial forms of lung disease, might be treatable in the future with this type of approach."