Latest news with #UniversityOfNevada
Yahoo
23-07-2025
- Science
- Yahoo
Physicists Blast Gold to Astonishing Temperatures, Overturning 40 Years of Physics
Physicists superheated gold to 14 times its melting point, disproving a long-standing prediction about the temperature limits of solids Gold usually melts at 1,300 kelvins—a temperature hotter than fresh lava from a volcano. But scientists recently shot a nanometers-thick sample of gold with a laser and heated it to an astonishing 19,000 kelvins (33,740 degrees Fahrenheit)—all without melting the material. The feat was completely unexpected and has overturned 40 years of accepted physics about the temperature limits of solid materials, the researchers report in a paper published in the journal Nature. 'This was extremely surprising,' says study team member Thomas White of the University of Nevada, Reno. 'We were totally shocked when we saw how hot it actually got.' The measured temperature is well beyond gold's proposed 'entropy catastrophe' limit, the point at which the entropy, or disorder, in the material should force it to melt. Past that limit, theorists had predicted solid gold would have a higher entropy than liquid gold—a clear violation of the laws of thermodynamics. By measuring such a blistering temperature in a solid in the new study, the researchers disproved the prediction. They realized that their solid gold was able to become so superheated because it warmed incredibly quickly: their laser blasted the gold for just 45 femtoseconds, or 45 quadrillionths of a second—a 'flash heating' that was far too fast to allow the material time to expand and thus kept the entropy within the bounds of known physics. 'I would like to congratulate the authors on this interesting experiment,' says Sheng-Nian Luo, a physicist at Southwest Jiaotong University in China, who has studied superheating in solids and was not involved in the new research. 'However, melting under such ultrafast, ultrasmall, ultracomplex conditions could be overinterpreted.' The gold in the experiment was an ionized solid heated in a way that may have caused a high internal pressure, he says, so the results might not apply to normal solids under regular pressures. The researchers, however, doubt that ionization and pressure can account for their measurements. The extreme temperature of the gold 'cannot reasonably be explained by these effects alone,' White says. 'The scale of superheating observed suggests a genuinely new regime.' [Sign up for Today in Science, a free daily newsletter] To take the gold's temperature, the team used another laser—in this case, the world's most powerful x-ray laser, which is three kilometers (1.9 miles) long. The machine, the Linac Coherent Light Source at the SLAC National Accelerator Laboratory in California, accelerates electrons to more than 99 percent the speed of light and then shoots them through undulating magnetic fields to create a very bright beam of one trillion (1012) x-ray photons. When this laser fired at the superheated sample, the x-ray photons scattered off atoms inside the material, allowing the researchers to measure the atoms' velocities to effectively take the gold's temperature. 'The biggest lasting contribution is going to be that we now have a method to really accurately measure these temperatures,' says study team member Bob Nagler, a staff scientist at SLAC. The researchers hope to use the technique on other types of 'warm dense matter,' such as materials meant to mimic the insides of stars and planets. Until now, they've had no good way to take the temperature of matter in such toasty states, which usually last just fractions of a second. After the gold trial, the team turned its laser thermometer on a piece of iron foil that had been heated with a laser shock wave to simulate conditions at the center of our planet. 'With this method, we can determine what the melting temperature is,' Nagler says. 'These questions are super important if you want to model the Earth.' The temperature technique should also be useful for predicting how materials used in fusion experiments will behave. The National Ignition Facility at Lawrence Livermore National Laboratory, for example, shoots lasers at a small target to rapidly heat and compress it to ignite thermonuclear fusion. Physicists can now determine the melting point for different targets—meaning the whole field could be heating up in the near future. Solve the daily Crossword
BreakingNews.ie
03-06-2025
- Health
- BreakingNews.ie
Six things you need to know about Alzheimer's – as drug trials bring new hope
Excitement is building as a new review shows a rise in the number of potential drugs that could treat or prevent Alzheimer's disease. Led by an expert from the University of Nevada in the US and published in the journal Alzheimer's & Dementia: Translational Research and Clinical Interventions, the review reveals that 182 clinical trials are underway in 2025, a rise of 11 per cent from the previous year, assessing the impact 138 potential drugs. Advertisement Notably, one-third of these drugs are repurposed medications originally developed for other conditions like diabetes, multiple sclerosis and high cholesterol. In response to this encouraging development, Emma Taylor, information services manager at Alzheimer's Research, has addressed some common misconceptions about the disease, highlighting six key facts everyone should know about Alzheimer's… 1. Alzheimer's and dementia are not the same thing Learn the distinct difference between Alzheimer's and dementia 'A lot of people get confused between Alzheimer's and dementia and aren't really sure what the difference is,' recognises Taylor. 'The way I describe it is that dementia is the group of symptoms – so things like memory loss, confusion, personality and behavioural changes – and Alzheimer's is one of the causes of those symptoms.' Research generally associates Alzheimer's disease with the accumulation of two proteins, amyloid and tau, says Taylor. Advertisement 'These toxic proteins damage our brain cells, which are what is used to communicate messages throughout our body,' she explains. 'Overtime, as more brain cells die, it becomes harder for our brain overall to carry out its normal functions. So, depending on where in the brain the damage starts, that indicates what kind of symptoms someone will experience. 'That's why in Alzheimer's early symptoms are often memory loss and confusion because Alzheimer's tends to, but doesn't always, start in the memory centres of the brain.' 2. There are 14 potential risk factors 'A lot of the risk factors for dementia are linked to our heart health,' says Taylor. 'So, we know that what's good for your heart is good for your brain as well. 'Things like having a healthy diet, exercising regularly, limiting the amount of alcohol you drink, not smoking, keeping your blood pressure and cholesterol under control etc is really important to improve or maintain our brain health and reduce our risk of dementia. Advertisement 'These risk factors, there are 14 in total, have been linked to 45 per cent of dementia cases worldwide. So, if those risk factors were completely eliminated, then up to 45 per cent would be prevented or delayed.' 3. It isn't an inevitable part of ageing 'A lot of people think it's an inevitable part of ageing, but it's definitely not – we can do things to reduce our risk of dementia,' says Taylor. While Alzheimer's disease is more common in older adults, it can also affect younger people. 'People as young as 30 have developed Alzheimer's and obviously that is quite rare, but it really does show that it's not just a part of ageing,' says Taylor. 'It's a biological disease and if something goes wrong, then we can try and find a way to make it right – that's where research comes in.' Advertisement 4. It isn't just about memory loss Memory loss is just one possible symptom of Alzheimer's 'I think a lot of people just think of Alzheimer's as memory loss, but it can affect a lot of different aspects of someone's memory and thinking,' highlights Taylor. 'Someone might become very confused and might not be sure of the time or the date, they might misplace things a lot or put them in odd places, like putting a TV remote in the fridge.' Alzheimer's can also really affect language skills. 'People might have problems finding the right words or understanding the meaning of words or might struggle to follow conversations, and that might mean that they become quite withdrawn,' says Taylor. In addition, there's a lot of links between Alzheimer's and mood and behaviour changes. Advertisement 'People can become low in mood. other people may become more agitated or aggressive, and that's a really heartbreaking thing for someone to go through,' says Taylor. 5. Getting a diagnosis can be beneficial 'People often ring us and say why would I bother going to the doctor if there's no cure yet – but I think the benefits of getting a diagnosis is that support and understanding that you get from knowing what's going on, and the ability to plan ahead,' says Taylor. 'Getting a diagnosis means you can put things in place like the lasting power of attorney and sort out your will and finances while you have time. 'Getting an early diagnosis also means getting those treatments while they're likely to work best, and a diagnosis also provides more opportunities to take part in research, so the future generations don't have to go through the same thing.' 6. Remember to be patient with loved ones who have Alzheimer's Patience and understanding are key 'Someone might change quite a lot when they have Alzheimer's, but it doesn't mean that they deep down aren't the same person,' emphasises Taylor. 'Someone's behaviour might change quite drastically throughout the course of the disease but it's not coming from a bad place. 'So, patience and understanding is really key when dealing with anyone with any form of dementia. Treasure the time that you have with them.'
