Human hair-inspired body armour in the offing

January 18, 2017

Los Angeles, Jan 18: Scientists have found why human hair is incredibly strong and resistant to breaking, a finding that may lead to new generation of materials for body armours and even help create better hair care products.

hairHair has a strength to weight ratio comparable to steel. It can be stretched up to one and a half times its original length before breaking, researchers said.

"We wanted to understand the mechanism behind this extraordinary property," said Yang Yu, a PhD student at the University of California San Diego.

"We're interested in understanding the correlation between the structure and the properties of biological materials to develop synthetic materials and designs - based on nature - that have better performance than existing ones," said Marc Meyers, a professor at UC San Diego.

Researchers examined at the nanoscale level how a strand of human hair behaves when it is deformed, or stretched. The team found that hair behaves differently depending on how fast or slow it is stretched. The faster hair is stretched, the stronger it is.

"Think of a highly viscous substance like honey. If you deform it fast it becomes stiff, but if you deform it slowly it readily pours," said Meyers.

Hair consists of two main parts - the cortex, which is made up of parallel fibrils, and the matrix, which has an amorphous (random) structure.

The matrix is sensitive to the speed at which hair is deformed, while the cortex is not. The combination of these two components, Yu explained, is what gives hair the ability to withstand high stress and strain.

As hair is stretched, its structure changes in a particular way. At the nanoscale, the cortex fibrils in hair are each made up of thousands of coiled spiral-shaped chains of molecules called alpha helix chains.

As hair is deformed, the alpha helix chains uncoil and become pleated sheet structures known as beta sheets. This structural change allows hair to handle up a large amount deformation without breaking.

This structural transformation is partially reversible. When hair is stretched under a small amount of strain, it can recover its original shape. Stretch it further, the structural transformation becomes irreversible.

"This is the first time evidence for this transformation has been discovered," Yu said.

"Hair is such a common material with many fascinating properties," said Bin Wang, a UC San Diego PhD alumna.

The team also conducted stretching tests on hair at different humidity levels and temperatures. At higher humidity levels, hair can withstand up to 70 to 80 per cent deformation before breaking. Water essentially "softens" hair - it enters the matrix and breaks the sulphur bonds connecting the filaments inside a strand of hair.

Researchers also found that hair starts to undergo permanent damage at 60 degrees Celsius. Beyond this temperature, hair breaks faster at lower stress and strain.

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Agencies
April 15,2020

Dear parents, if you want your children to have proper sleep, read this carefully. Joining a growing list of studies that tell parents to shun devices at bed-time, researchers say that children who use devices and decide what time they go to sleep, achieve less sleep and feel more sleepier the following day than their peers.

The study of children in this age-group (aged 11 to 13 years), published in the New Zealand Medical Journal, found most (72 per cent) of the 163 students interviewed by University of Otago researchers achieved recommended guidelines of an average 9 to 11 hours sleep nightly over one week.

"But that also means that almost one in four students did not achieve sleep within these guidelines, which highlights an area for improvement," said study researcher Kate Ford.

However, consistent with previous research in 15 to 17-year-old New Zealanders, the study results show less sleep on the nights where devices are used in the hour before bed.

According to the researchers, students who used devices before going to sleep were also more likely to report that they felt sleepy the following morning. Watching television before bed had no significant effect on sleep length.

There were also some interesting observations over the weekends where students went to bed later but woke later achieving similar sleep length to the school days, the researchers said.

A small group of students (six per cent) who reported less than seven hours of sleep, including a small number reporting not sleeping at all, according to the study,

Therefore, while the average across the week of 72 per cent of students reporting adequate sleep is reassuring, it is far from the goal of every child achieving sleep within the recommended guidelines," Ford said.

Dr Paul Kelly, head of the Sleep Health Service at Canterbury District Health Board, supervised the study and explained that the foundations for good health are based on proper nutrition, regular exercise and good sleep quality.

Sleep quality is often overlooked as a contributory factor to poor health.

"The study findings suggest the need for parental guidance around bedtimings and moderation of the use and availability of electronic devices before bed," Kelly said.

"Respect and protect your sleep, as good daytime functioning is reliant on adequate sleep," Kelly added.

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Agencies
May 8,2020

As Europe and the US loosen their lockdowns against the coronavirus, health experts are expressing growing dread over what they say is an all-but-certain second wave of deaths and infections that could force governments to clamp back down.

"We are risking a backslide that will be intolerable," said Dr Ian Lipkin of Columbia University's Center for Infection and Immunity.

Around the world, German authorities began drawing up plans in case of a resurgence of the virus. Experts in Italy urged intensified efforts to identify new victims and trace their contacts. And France, which has not yet eased its lockdown, has already worked up a "reconfinement plan" in the event of a new wave.

"There will be a second wave, but the problem is to which extent. Is it a small wave or a big wave? It is too early to say," said Olivier Schwartz, head of the virus unit at France's Pasteur Institute.

In the US, with about half of the states easing their shutdowns to get their economies restarted and cellphone data showing that people are becoming restless and increasingly leaving home, public health authorities are worried.

Many states have not put in place the robust testing that experts believe is necessary to detect and contain new outbreaks. And many governors have pressed ahead before their states met one of the key benchmarks in the Trump administration's guidelines for reopening -- a 14-day downward trajectory in new illnesses and infections.

"If we relax these measures without having the proper public health safeguards in place, we can expect many more cases and, unfortunately, more deaths," said Josh Michaud, associate director of global health policy with the Kaiser Family Foundation in Washington.

Cases have continued to rise steadily in places such as Iowa and Missouri since the governors began reopening, while new infections have yo-yoed in Georgia, Tennessee and Texas.

Lipkin said he is most worried about two things: the reopening of bars, where people crowd together and lose their inhibitions, and large gatherings such as sporting events, concerts and plays. Preventing outbreaks will require aggressive contact tracing powered by armies of public health workers hundreds of thousands of people strong, which the US does not yet have, Lipkin said.

Worldwide the virus has infected more than 36 lakh people and killed over a quarter-million, according to a tally by Johns Hopkins University that experts agree understates the dimensions of the disaster because of limited testing, differences in counting the dead and concealment by some governments.

The US has recorded over 70,000 deaths and 12 lakh confirmed infections, while Europe has reported over 140,000 dead.

This week, the researchers behind a widely cited model from the University of Washington nearly doubled their projection of deaths in the US to around 134,000 through early August, in large part because of the easing of state stay-at-home restrictions. Newly confirmed infections per day in the US exceed 20,000 and deaths per day are running well over 1,000.

In hard-hit New York City, which has managed to bring down deaths dramatically even as confirmed infections continue to rise around the rest of the country, Mayor Bill de Blasio warned that some states may be reopening too quickly.

"My message to the rest of the country is learn from how much effort, how much discipline it took to finally bring these numbers down and follow the same path until you are sure that it is being beaten back," he said on CNN, "or else, if this thing boomerangs, you are putting off any kind of restart or recovery a hell of a lot longer."

A century ago, the Spanish flu epidemic's second wave was far deadlier than its first, in part because authorities allowed mass gatherings from Philadelphia to San Francisco.

"It is clear to me that we are in a critical moment of this fight. We risk complacency and accepting the preventable deaths of 2,000 Americans each day," epidemiologist Caitlin Rivers, a professor at Johns Hopkins, told a House subcommittee in Washington.

President Donald Trump, who has pressed hard to ease the restrictions that have throttled the economy and thrown more than three crore Americans out of work, pulled back Wednesday on White House plans revealed a day earlier to wind down the coronavirus task force.

He tweeted that the task force will continue meeting indefinitely with a "focus on SAFETY & OPENING UP OUR COUNTRY AGAIN".

Underscoring those economic concerns, the European Union predicted the worst recession in its quarter-century history. And the US unemployment rate for April, which comes out on Friday, is expected to hit a staggering 16 per cent, a level last seen during the Great Depression of the 1930s.

Governors continue to face demands, even lawsuits, to reopen. In Michigan, where armed demonstrators entered the Capitol last week, the Republican-led Legislature sued Democratic Governor Gretchen Whitmer, asking a judge to declare invalid her stay-at-home order, which runs at least through May 15.

In hard-hit Italy, which has begun easing restrictions, Dr Silvio Brusaferro, president of the Superior Institute of Health, urged "a huge investment" of resources to train medical personnel to monitor possible new cases of the virus, which has killed about 30,000 people nationwide.

He said that contact-tracing apps which are being built by dozens of countries and companies are not enough to manage future waves of infection.

German Chancellor Angela Merkel said after meeting with the country's 16 governors that restaurants and other businesses will be allowed to reopen in the coming weeks but that regional authorities will have to draw up a "restriction concept" for any county that reports 50 new cases for every 100,000 inhabitants within a week.

Lothar Wieler, head of Germany's national disease control centre, said scientists "know with great certainty that there will be a second wave" of infections.

Britain, with over 30,000 dead, the second-highest death toll in the world behind the US, plans to extend its lockdown but has begun recruiting 18,000 people to trace contacts of those infected.

In other developments, the US Centers for Disease Control and Prevention said nearly 5,000 coronavirus illnesses and at least 88 deaths have been reported among inmates in American jails and prisons. An additional 2,800 cases and 15 deaths were reported among guards and other staff members.

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Agencies
February 10,2020

Washington D.C, Feb 10: Children's vulnerability towards depression, anxiety, impulsive behaviour, and poor cognitive performance could be determined by considering the hours of sleep they manage to get.

Sleep states are active processes that support the reorganisation of brain circuitry. This makes sleep especially important for children, whose brains are developing and reorganising rapidly.

In a study by researchers from the University of Warwick -- recently published in the journal Molecular Psychiatry -- cases of 11,000 children aged between 9 and 11 years from the Adolescent Brain Cognitive Development dataset were analyzed to find out the relationship between sleep duration and brain structure.

The study was carried out by researchers Professor Jianfeng Feng, Professor Edmund Rolls, Dr. Wei Cheng and colleagues from the University of Warwick's Department of Computer Science and Fudan University.

Measures of depression, anxiety, impulsive behaviour and poor cognitive performance in the children were associated with shorter sleep duration. Moreover, the depressive problems were associated with short sleep duration one year later.

The reduced brain volume of areas such as orbitofrontal cortex, prefrontal, and temporal cortex, precuneus, and supramarginal gyrus was found to be associated with the shorter sleep duration.

Professor Jianfeng Feng, from the University of Warwick's Department of Computer Science, comments: "The recommended amount of sleep for children 6 to 12 years of age is 9-12 hours. However, sleep disturbances are common among children and adolescents around the world due to the increasing demand on their time from school, increased screen time use, and sports and social activities."

A previous study showed that about 60 per cent of adolescents in the United States receive less than eight hours of sleep on school nights.

Professor Jianfeng Feng further added: "Our findings showed that the total score for behavior problems in children with less than 7 hours sleep was 53 per cent higher on average and the cognitive total score was 7.8 per cent lower on average than for children with 9-11 hours of sleep. It highlights the importance of enough sleep in both cognition and mental health in children."

Professor Edmund Rolls from the University of Warwick's Department of Computer Science also commented: "These are important associations that have been identified between sleep duration in children, brain structure, and cognitive and mental health measures, but further research is needed to discover the underlying reasons for these relationships."

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