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New crystalline form of ice: Scientists elucidate crystal structure for exotic ice XIX

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New crystalline form of ice: Scientists elucidate crystal structure for exotic ice XIX

Three years ago, chemists found evidence for the existence of a new variety of ice. Until then, 18 types of crystalline ice were known. The team now reports on the elucidation of the crystal structure of ice XIX using neutron diffraction.

Ice is a very versatile material. In snowflakes or ice cubes, the oxygen atoms are arranged hexagonally. This ice form is called ice one (ice I). “”Strictly speaking, however, these are not actually perfect crystals, but disordered systems in which the water molecules are randomly oriented in different spatial directions,” explains Thomas Loerting from the Institute of Physical Chemistry at the University of Innsbruck, Austria. Including ice I, 18 crystalline forms of ice were known so far, which differ in the arrangement of their atoms. The different types of ice, known as polymorphs, form depending on pressure and temperature and have very different properties. For example, their melting points differ by several hundred degrees Celsius. “It’s comparable to diamond and graphite, both of which are made of pure carbon,” the chemist explains.
Icy variety
When conventional ice I is cooled strongly, the hydrogen atoms can arrange themselves periodically in addition to the oxygen atoms if the experiment is conducted correctly. Below minus 200 degrees Celsius, this can lead to the formation of so-called ice XI, in which all water molecules are ordered according to a specific pattern. Such ordered ice forms differ from the disordered parental forms, especially in their electrical properties. In the current work, the Innsbruck chemists deal with the parent form ice VI, which is formed at high pressure, for example in the Earth’s mantle. Like hexagonal ice, this high-pressure form of ice is not a completely ordered crystal. More than 10 years ago, researchers at the University of Innsbruck produced a hydrogen-ordered variant of this ice, which found its way into textbooks as ice XV. By changing the manufacturing process, three years ago Thomas Loerting’s team succeeded for the first time in creating a second ordered form for ice VI. To do this, the scientists significantly slowed down the cooling process and increased the pressure to around 20 kbar. This enabled them to arrange the hydrogen atoms in a second way in the oxygen lattice and produce ice XIX. “We found clear evidence at that time that it is a new ordered variant, but we were not able to elucidate the crystal structure.” Now his team has succeeded in doing just that using the gold standard for structure determination — neutron diffraction.Crystal structure solved

For the clarification of the crystal structure, an essential technical hurdle had to be overcome. In an investigation using neutron diffraction, it is necessary to replace the light hydrogen in water with deuterium (“heavy hydrogen”). “”Unfortunately, this also changes the time scales for ordering in the ice manufacturing process,” says Loerting. “But Ph.D. student Tobias Gasser then had the crucial idea of adding a few percent of normal water to the heavy water — which turned out to speed up the ordering immensely.” With the ice obtained in this way, the Innsbruck scientists were finally able to measure neutron data on the high-resolution HRPD instrument at the Rutherford Appleton Laboratory in England and painstakingly solve the crystal structure of ice XIX. This required finding the best crystal structure out of several thousand candidates from the measured data — much like searching for a needle in a haystack. A Japanese research group confirmed the Innsbruck result in another experiment under different pressure conditions. Both papers have now been published jointly in Nature Communications.

Six ice forms discovered in Innsbruck

While conventional ice and snow are abundant on Earth, no other forms are found on the surface of our planet — except in research laboratories. However, the high-pressure forms ice VI and ice VII are found as inclusions in diamonds and have therefore been added to the list of minerals by the International Mineralogical Association (IMA). Many varieties of water ice are formed in the vastness of space under special pressure and temperature conditions. They are found, for example, on celestial bodies such as Jupiter’s moon Ganymede, which is covered by layers of different ice varieties.

Ice XV and ice XIX represents the first sibling pair in ice physics in which the oxygen lattice is the same, but the pattern how hydrogen atoms are ordered is different. “”This also means that for the first time it will now be possible to realize the transition between two ordered ice forms in experiments,” Thomas Loerting is pleased to report. Since the 1980s, researchers at the University of Innsbruck, Austria, are now responsible for the discovery of four crystalline as well as two amorphous ice forms.

The current research work was carried out within the framework of the Research Platform for Materials and Nanoscience at the University of Innsbruck and was financially supported by the Austrian Science Fund FWF.

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Large wildfires create weather that favors more fire

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New crystalline form of ice: Scientists elucidate crystal structure for exotic ice XIX


A new UC Riverside study shows soot from large wildfires in California traps sunlight, making days warmer and drier than they ought to be.

Many studies look at the effect of climate change on wildfires. However, this study sought to understand the reverse — whether large fires are also changing the climate.

“I wanted to learn how the weather is affected by aerosols emitted by wildfires as they’re burning,” said lead study author and UCR doctoral candidate James Gomez.

To find his answers, Gomez analyzed peak fire days and emissions from every fire season over the past 20 years. Of these fire days, he examined a subset that occurred when temperatures were lower, and humidity was higher. “I looked at abnormally cool or wet days during fire season, both with and without fires. This mostly takes out the fire weather effects,” Gomez said.

Published in the journal Atmospheric Chemistry and Physics, the study found that large fires did have an effect. They made it hotter and drier than usual on the days the fires burned. The extra heat and aridity may then make conditions favorable for more fire.

“It appears these fires are creating their own fire weather,” Gomez said.

The most intense fires occurred in Northern California, where fire-fueling vegetation is denser than elsewhere in the state. On average, temperatures were about 1 degree Celsius warmer per day during the fires.

There are likely two reasons for this. One — soot traps heat, and two — the extra heat reduces humidity in the atmosphere, making it more difficult for clouds to form.

“Fires emit smoke with black carbon, or soot. Since it is very dark, the soot absorbs sunlight more readily than bright or reflective things,” Gomez said.

There are two types of aerosols: reflective and absorptive. Sulfate aerosols, which are byproducts of fossil fuel burning, are reflective and can cool the environment. These particles reflect the sun’s energy back into space, keeping it out of the atmosphere.

Recent UCR research points to an unfortunate byproduct of improving air quality by reducing sulfate aerosols. Since these particles have a cooling effect, removing them makes climate change more severe and leads to an increase in wildfires, especially in northern hemisphere forests.

Sulfate aerosols can also help make clouds brighter, more reflective, and more effective at cooling the planet.

The researchers note that the only way to prevent additional wildfires when cleaning up reflective sulfate air pollution is to simultaneously reduce emissions of greenhouse gases like carbon dioxide and methane.

Absorptive aerosols have the opposite effect. They trap light and heat in the atmosphere, which can raise temperatures. Black carbon, the most common aerosol emission from wildfires, is an absorbing aerosol. They not only directly make temperatures hotter, but indirectly as well by discouraging cloud formation and precipitation.

“What I found is that the black carbon emitted from these California wildfires is not increasing the number of clouds,” Gomez said. “It’s hydrophobic.” Fewer clouds mean less precipitation, which is problematic for drought-prone states.

While some studies have shown an association between fires and brighter, more numerous clouds, this one did not.

Notably, the study found that days with fewer fire emissions had a more muted effect on the weather. “If the aerosols are coming out in smaller amounts and more slowly, the heating effect is not as pronounced,” Gomez said.

Gomez is hopeful that mitigating CO2 emissions, alongside better land management practices, can help reduce the number of large wildfires.

“There is a buildup of vegetation here in California. We need to allow more frequent small fires to reduce the amount of fuel available to burn,” Gomez said. “With more forest management and more prescribed burns, we could have fewer giant fires. That is in our control.”



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Astronomers see a massive black hole awaken in real time

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New crystalline form of ice: Scientists elucidate crystal structure for exotic ice XIX


In late 2019 the previously unremarkable galaxy SDSS1335+0728 suddenly started shining brighter than ever before. To understand why, astronomers have used data from several space and ground-based observatories, including the European Southern Observatory’s Very Large Telescope (ESO’s VLT), to track how the galaxy’s brightness has varied. In a study out today, they conclude that they are witnessing changes never seen before in a galaxy — likely the result of the sudden awakening of the massive black hole at its core.

Imagine you’ve been observing a distant galaxy for years, and it always seemed calm and inactive,” says Paula Sánchez Sáez, an astronomer at ESO in Germany and lead author of the study accepted for publication in Astronomy & Astrophysics. “Suddenly, its [core] starts showing dramatic changes in brightness, unlike any typical events we’ve seen before.” This is what happened to SDSS1335+0728, which is now classified as having an ‘active galactic nucleus’ (AGN) — a bright compact region powered by a massive black hole — after it brightened dramatically in December 2019 [1].

Some phenomena, like supernova explosions or tidal disruption events — when a star gets too close to a black hole and is torn apart — can make galaxies suddenly light up. But these brightness variations typically last only a few dozen or, at most, a few hundreds of days. SDSS1335+0728 is still growing brighter today, more than four years after it was first seen to ‘switch on’. Moreover, the variations detected in the galaxy, which is located 300 million light-years away in the constellation Virgo, are unlike any seen before, pointing astronomers towards a different explanation.

The team tried to understand these brightness variations using a combination of archival data and new observations from several facilities, including the X-shooter instrument on ESO’s VLT in Chile’s Atacama Desert [2]. Comparing the data taken before and after December 2019, they found that SDSS1335+0728 is now radiating much more light at ultraviolet, optical, and infrared wavelengths. The galaxy also started emitting X-rays in February 2024. “This behaviour is unprecedented,” says Sánchez Sáez, who is also affiliated with the Millennium Institute of Astrophysics (MAS) in Chile.

“The most tangible option to explain this phenomenon is that we are seeing how the [core] of the galaxy is beginning to show (…) activity,” says co-author Lorena Hernández García, from MAS and the University of Valparaíso in Chile. “If so, this would be the first time that we see the activation of a massive black hole in real time.”

Massive black holes — with masses over one hundred thousand times that of our Sun — exist at the centre of most galaxies, including the Milky Way. “These giant monsters usually are sleeping and not directly visible,” explains co-author Claudio Ricci, from the Diego Portales University, also in Chile. “In the case of SDSS1335+0728, we were able to observe the awakening of the massive black hole, [which] suddenly started to feast on gas available in its surroundings, becoming very bright.”

“[This] process (…) has never been observed before,” Hernández García says. Previous studies reported inactive galaxies becoming active after several years, but this is the first time the process itself — the awakening of the black hole — has been observed in real time. Ricci, who is also affiliated with the Kavli Institute for Astronomy and Astrophysics at Peking University, China, adds: “This is something that could happen also to our own Sgr A*, the massive black hole (…) located at the centre of our galaxy,” but it is unclear how likely this is to happen.

Follow-up observations are still needed to rule out alternative explanations. Another possibility is that we are seeing an unusually slow tidal disruption event, or even a new phenomenon. If it is in fact a tidal disruption event, this would be the longest and faintest such event ever observed. “Regardless of the nature of the variations, [this galaxy] provides valuable information on how black holes grow and evolve,” Sánchez Sáez says. “We expect that instruments like [MUSE on the VLT or those on the upcoming Extremely Large Telescope (ELT)] will be key in understanding [why the galaxy is brightening].”

Notes

[1] The SDSS1335+0728 galaxy’s unusual brightness variations were detected by the Zwicky Transient Facility (ZTF) telescope in the US. Following that, the Chilean-led Automatic Learning for the Rapid Classification of Events (ALeRCE) broker classified SDSS1335+0728 as an active galactic nucleus.

[2] The team collected archival data from NASA’s Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX), the Two Micron All Sky Survey (2MASS), the Sloan Digital Sky Survey (SDSS), and the eROSITA instrument on IKI and DLR’s Spektr-RG space observatory. Besides ESO’s VLT, the follow-up observations were conducted with the Southern Astrophysical Research Telescope (SOAR), the W. M. Keck Observatory, and NASA’s Neil Gehrels Swift Observatory and Chandra X-ray Observatory.



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Bedtime battles: 1 in 4 parents say their child can’t go to sleep because they’re worried or anxious

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Many bedtime battles stem from children’s after dark worries, suggests a new national poll.

And while most families have bedtime rituals to help their little ones ease into nighttime, many rely on strategies that may increase sleep challenges long term, according to the University of Michigan Health C.S. Mott Children’s Hospital National Poll on Children’s Health.

Overall, one in four parents describe getting their young child to bed as difficult — and these parents are less likely to have a bedtime routine, more likely to leave on a video or TV show, and more likely to stay with their child until they’re asleep.

“Our report reinforces the common struggle of getting young children to sleep. When this transition to bedtime becomes a nightly conflict, some parents may fall into habits that work in the moment but could set them up for more sleep issues down the road,” said Mott Poll co-director Sarah Clark, M.P.H.

“Establishing a consistent bedtime routine is crucial. When children don’t get enough rest, it can impact their physical development, emotional regulation and behavior.”

Nearly one in five parents say they have given their kids melatonin to help with sleep while a third stay in the room until their child completely dozes off, according to the nationally representative poll that includes responses from 781 parents of children ages one to six surveyed in February.

Nighttime worries interfere with sleep

Parents share common reasons behind bedtime struggles, with nearly a quarter saying their child’s sleep is often or occasionally delayed due to being worried or anxious.

A particular challenge, parents say, is when children don’t stay asleep. More than a third of parents say their child wakes up upset or crying, with more than 40% saying their child moves to their parents’ bed and about 30% saying children insist that the parent sleep in their room.

“Many young children go through stages when they become scared of the dark or worry that something bad might happen, causing them to delay bedtime or become distressed by parents leaving the room. Bad dreams or being awakened in the middle of the night can also disrupt sleep,” Clark said.

“Although this is a normal part of a child’s development, it can be frustrating when parents already feel tired themselves at the end of the day. Parents should find a balance between offering reassurance and comfort while maintaining some boundaries that help ensure everyone — both kids and adults — get adequate sleep.”

More findings from the report, plus Clark’s recommendations for helping young children fall and stay asleep:

Stick to a regular bedtime routine

Most parents polled report having a bedtime routine for their child, often including brushing teeth, reading bedtime stories and/or bathing. Less than half also say their child has a drink of water or snack, turns off devices, prays and talks about their day.

Other bedtime habits include holding a blanket or stuff animal or sucking a pacifier or fingers.

Not only does having a consistent bedtime routine help make the nighttime transition smoother, Clark says, it also provides one-on-one time, allowing the child to get their parent’s full attention.

“A predictable bedtime routine provides a sense of security and comfort and signals to the child that it’s time to slow down,” she said.

“Knowing what to expect next can reduce anxiety and help children feel safe and relaxed. Having this dedicated time with parents also promotes bonding and emotional connection, creating positive associations with bedtime.”

Nearly two-thirds of parents also said children staying up to play was a major factor in delaying sleep. Clark says, highlighting the need to wind down at least an hour before bed.

Promote an environment conducive to sleep

A little less than half of parents polled say their child sleeps in their own bedroom while less than a quarter share a bedroom with siblings or in the parents’ bedroom. One in 10 kids spend part the night in their own bedroom and part of the night with parents.

More than two-fifths of parents polled said noise from other rooms interfered with their child’s sleep.

“The sleep environment can have a major effect on a child’s sleep quality, including getting to sleep and staying asleep through the night,” Clark said.

“When possible, children should have their own bed in a room that is quiet, without a lot of noise from other family members.”

Many parents polled also use a nightlight or crack the bedroom door so the child isn’t in complete darkness, Clark says, but parents should make sure the light does not shine directly at the child’s face.

Some parents also play calming music or stories to help their child go to sleep, while others use a white noise machine or app. However, Clark cautions to keep white noise machines at no more than 50 decibels and placed at least seven feet from the child’s bed to prevent unintended damage to the child’s hearing.

Talk to a doctor before using aids like melatonin

Many types of melatonin products are advertised as being appropriate for children but these products have not undergone rigorous testing for safety and effectiveness, and their side effects and long term impact on a child’s growth and development are unknown, Clark says.

“Although melatonin is a natural hormone that regulates sleep-wake cycles and may be fine to use occasionally, parents shouldn’t rely on it as a primary sleep aid,” Clark said.

“Parents who are considering giving melatonin to their young child should consult with their pediatrician to discuss options and rule out other causes of sleep problems first.”

If using melatonin, parents should also start with the lowest dose possible.

In addition, it’s important to keep electronics such as tablets or televisions out of children’s bedroom, as the blue light emitted by many of these screens interferes with the natural production of melatonin.

Offer comfort but enforce boundaries

Parents can help ease little ones’ anxiety by allowing extra time to let them talk about their day, which might draw out specific worries and give parents a chance to provide compassion and reassurance, Clark said.

Rather than remaining in the room, parents can also offer to check on the child every few minutes, which acknowledges the child’s fears and offers a reassuring presence, but still maintains a calm sleep environment and promotes sleep independence.

“Families can incorporate comforting rituals to help transform nighttime fears into a calming experience,” Clark said.

Have a consistent approach when children wake up in the night

Some children are prone to vivid dreams or nightmares and may have difficulty getting back to sleep. Parents should decide on their approach to this situation and stick with it, Clark says, whether it’s taking the child back to bed or allowing them to stay in the parents’ room.

“Being consistent in carrying out that approach will help the child adjust and be more likely to return to sleep,” Clark said.

Ease into changes in sleep patterns, such as dropping naps

For young children, a major sleep-related transition is discontinuing daytime naps. In general, children ages one to two should get 11-14 hours of sleep with naps while the amount of recommended sleep decreases slightly from ages three to six.

If children are taking longer to fall asleep at nap time, resisting naps or suddenly having difficulty falling asleep at night or waking up earlier than usual in the morning, it may be time to drop the nap, Clark says.

“Parents may need to adjust sleep routines gradually to transition to changes to a child’s sleep patterns,” Clark said.

Other changes that can affect a child’s sleep include transitioning from a crib to a toddler bed, starting school, having a change in their daytime routine, or being outdoors for longer than usual.



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