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How Hand Sanitizer Works (And Why It Isn't a Substitute for Soap)

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You likely know it's mostly alcohol. So why doesn't hand sanitizer look, smell, and feel like the stuff doctors use to clean their tools? (Or for that matter, the kind we drink?) The difference is in the details, the American Chemical Society's latest Reactions video explains below.

Technically, most popular hand sanitizers are made from forms of alcohol including ethanol (the same stuff in wine, beer, and liquor) and isopropanol, which is found in rubbing alcohol. These dissolve the outer coating of viruses and bacteria, which ultimately ends up killing the pesky skin hitchhikers.

That said, the substances above only comprise around 70 percent of the active ingredients in hand sanitizer. The rest are added to give the drugstore staple its gel-like consistency, softening properties, and its botanical fragrance. In some cases, manufacturers might even add some foul-tasting compounds to the mix, to deter users from potentially taking an ill-advised sip.

These mixtures are typically billed as "killing 99.99 percent of germs." In lab conditions, they can nearly eradicate certain strains of bacteria, but not all of those commonly found on your hands. Nevertheless, they do a pretty effective job.

Some health-conscious purchasers may worry that hand sanitizer will lead to the emergence of super-germs, kind of like antibiotic resistance. Here's the good news: Bacteria can't develop ultra-strong proteins or membranes as a response to being detonated by alcohol, so feel free to keep on squirting the aloe-scented stuff all winter long. The bad news? It doesn't physically wash dirt from hands. For that, you'll have to rely on old-fashioned soap and water (which don't fit nearly as conveniently into pockets or purses).

Find out what other compounds lurk invisibly inside your trusty bottle of hand sanitizer, and how it works to blast germs, by watching the video below.

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New Patient Test Could Suggest Whether Therapy or Meds Will Work Better for Anxiety
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Like many psychological disorders, there's no one-size-fits-all treatment for patients with anxiety. Some might benefit from taking antidepressants, which boost mood-affecting brain chemicals called neurotransmitters. Others might respond better to therapy, and particularly a form called cognitive behavioral therapy, or CBT.

Figuring out which form of treatment works best often requires months of trial and error. But experts may have developed a quick clinical test to expedite this process, suggests a new study published in the journal Neuropsychopharmacology.

Researchers at the University of Illinois at Chicago have noted that patients with higher levels of anxiety exhibit more electrical activity in their brains when they make a mistake. They call this phenomenon error-related negativity, or ERN, and measure it using electroencephalography (EEG), a test that records the brain's electric signals.

“People with anxiety disorders tend to show an exaggerated neural response to their own mistakes,” the paper’s lead author, UIC psychiatrist Stephanie Gorka, said in a news release. “This is a biological internal alarm that tells you that you've made a mistake and that you should modify your behavior to prevent making the same mistake again. It is useful in helping people adapt, but for those with anxiety, this alarm is much, much louder.”

Gorka and her colleagues wanted to know whether individual differences in ERN could predict treatment outcomes, so they recruited 60 adult volunteers with various types of anxiety disorders. Also involved was a control group of 26 participants with no history of psychological disorders.

Psychiatrists gauged subjects’ baseline ERN levels by having them wear an EEG cap while performing tricky computer tasks. Ultimately, they all made mistakes thanks to the game's challenging nature. Then, randomized subjects with anxiety disorders were instructed to take an SSRI antidepressant every day for three months, or receive weekly cognitive behavioral therapy for the same duration. (Cognitive behavioral therapy is a type of evidence-based talk therapy that forces patients to challenge maladaptive thoughts and develop coping mechanisms to modify their emotions and behavior.)

After three months, the study's patients took the same computer test while wearing EEG caps. Researchers found that those who'd exhibited higher ERN levels at the study's beginning had reduced anxiety levels if they'd been treated with CBT compared to those treated with medication. This might be because the structured form of therapy is all about changing behavior: Those with enhanced ERN might be more receptive to CBT than other patients, as they're already preoccupied with the way they act.

EEG equipment sounds high-tech, but it's relatively cheap and easy to access. Thanks to its availability, UIC psychiatrists think their anxiety test could easily be used in doctors’ offices to measure ERN before determining a course of treatment.

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Newly Discovered 350-Year-Old Graffiti Shows Sir Isaac Newton's Obsession With Motion Started Early
Hulton Archive//Getty Images
Hulton Archive//Getty Images

Long before he gained fame as a mathematician and scientist, Sir Isaac Newton was a young artist who lacked a proper canvas. Now, a 350-year-old sketch on a wall, discovered at Newton’s childhood home in England, is shedding new light on the budding genius and his early fascination with motion, according to Live Science.

While surveying Woolsthorpe Manor, the Lincolnshire home where Newton was born and conducted many of his most famous experiments, conservators discovered a tiny etching of a windmill next to a fireplace in the downstairs hall. It’s believed that Newton made the drawing as a boy, and may have been inspired by the building of a nearby mill.

A windmill sketch, believed to have been made by a young Sir Isaac Newton at his childhood home in Lincolnshire, England.
A windmill sketch, believed to have been made by a young Sir Isaac Newton at his childhood home in Lincolnshire, England.
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Newton was born at Woolsthorpe Manor in 1642, and he returned for two years after a bubonic plague outbreak forced Cambridge University, where he was studying mechanical philosophy, to close temporarily in 1665. It was in this rural setting that Newton conducted his prism experiments with white light, worked on his theory of “fluxions,” or calculus, and famously watched an apple fall from a tree, a singular moment that’s said to have led to his theory of gravity.

Paper was a scarce commodity in 17th century England, so Newton often sketched and scrawled notes on the manor’s walls and ceilings. While removing old wallpaper in the 1920s and '30s, tenants discovered several sketches that may have been made by the scientist. But the windmill sketch remained undetected for centuries, until conservators used a light imaging technique called Reflectance Transformation Imaging (RTI) to survey the manor’s walls.

Conservators using light technology to survey the walls of Woolsthorpe Manor,  the childhood home of Sir Isaac Newton.
A conservator uses light technology to survey the walls of Woolsthorpe Manor, the childhood home of Sir Isaac Newton.
National Trust

RTI uses various light conditions to highlight shapes and colors that aren’t immediately visible to the naked eye. “It’s amazing to be using light, which Newton understood better than anyone before him, to discover more about his time at Woolsthorpe,” conservator Chris Pickup said in a press release.

The windmill sketch suggests that young Newton “was fascinated by mechanical objects and the forces that made them work,” added Jim Grevatte, a program manager at Woolsthorpe Manor. “Paper was expensive, and the walls of the house would have been repainted regularly, so using them as a sketchpad as he explored the world around him would have made sense," he said.

The newly discovered graffiti might be one of many hidden sketches drawn by Newton, so conservators plan to use thermal imaging to detect miniscule variations in the thickness of wall plaster and paint. This technique could reveal even more mini-drawings.

[h/t Live Science]

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