Technology for sterilizing medical instruments goes solar

A sunlight-powered device equipped with an a lightweight gel makes steam hot enough to kill dangerous microbes. A sunlight-powered device equipped with an a lightweight gel makes steam hot enough to kill dangerous microbes.

An airy insulating material doubles the efficiency of a device that converts sunshine to heat, enabling solar-powered production of steam for sterilizing medical equipment.
Medical sterilization to prevent infections is routine in high-income nations, but less so in countries where people lack reliable access to energy. Existing solar absorbers can collect heat from sunlight but do not concentrate it well enough to create steam.
Evelyn Wang at the Massachusetts Institute of Technology in Cambridge and her colleagues modified an off-the-shelf solar absorber by adding a thin layer of foam tiles to the absorber's copper heat-collecting surface. The foam contains nanometre-scale silica particles that confer transparency, and is riddled with pores that help to trap heat, allowing light to pass through but preventing heat from leaving.
On a rooftop in Mumbai, India, water in a sealed chamber connected to the absorber began boiling within five minutes. For 30 minutes, the solar absorber produced steam at a temperature and pressure high enough to kill microorganisms.
The researchers hope their inexpensive device could help people in resource-poor regions to avoid infections acquired in medical settings.

FOUNTAIN OF YOUTH MIGHT BE FOUND IN YOUR SLEEP
Older people with sleep patterns like those of younger people tend to be in better physical and cognitive health than those with disrupted sleep.
Shaun Purcell at Harvard Medical School in Boston, Massachusetts, and his colleagues tracked the sleep of 3,819 people between 54 and 96 years old by recording their brain waves through electroencephalogram sensors that the participants wore throughout the night. The researchers then scored each person's sleep for more than 150 sleep characteristics and brain-activity patterns. These included factors such as sleep disturbance, the length of the sleep cycles in which dreams occur and preference for mornings or evenings.
The team found that older people with 'young' sleep patterns tended to have stronger cognitive abilities and a lower incidence of some health problems than did those whose sleep patterns more closely reflected their age. Although it is not clear whether the better sleep improves health or vice versa, the researchers say that techniques such as electrical stimulation of the brain might modify sleep patterns in older people and improve their health. Nature Hum. Behav. https://doi. org/fjp2 (2020)

TOXIC METAL LURKS IN THE OCEAN'S DEEPEST TRENCHES
At more than 10 kilometres deep, the Mariana Trench in the Pacific Ocean might seem remote enough to be pristine. But explorers have previously discovered plastic waste thereand now they've found mercury pollution, as well.
Mercury particles spread easily in the atmosphere, where they contaminate even the Arctic and Antarctic. Joel Blum at the University of Michigan in Ann Arbor and his colleagues wanted to see how much mercury has infiltrated the deep oceans.
The scientists collected snailfish (Notoliparis kermadecensis and Pseudoliparis swirei, pictured) and small marine creatures known as amphipods at the bottom of the Mariana Trench, as well as the Kermadec Trench, near New Zealand, at depths ranging from 6,000 to 10,250 metres. The authors measured the amount and chemical composition of mercury in the animals. The results turned out to be similar to those in creatures living just 500 metres from the surface.
Mercury pollution from human activities permeates the near-surface waters. Fish consume that mercury. When they die, they sink into deep-sea trenches, carrying it with them, the authors say.

HOW GUT MICROBES UNLEASH THE BODY'S ANTIVIRAL POWERS
Bacteria that thrive in the guts of humans and other mammals make a molecule that goads immune cells into action, thus helping to repel invasive viruses.
The mammalian gut is occupied by trillions of harmless bacteria, including the abundant species Bacteroides fragilis. To investigate the microbiomehost relationship, Dennis Kasper at Harvard Medical School in Boston, Massachusetts, and his colleagues analysed how a molecule in B. fragilis's outer membrane affects the immune system of mice. The team looked in particular at the rodents' dendritic cells, which act as the scouts of the immune system.
The authors found that when dendritic cells (pictured) were exposed to the bacterial molecule, they secreted a powerful signalling chemical called interferon-β. That chemical, in turn, switched on a battery of genes that affect the immune response. Dendritic cells that were combined with the bacterial molecule in a dish largely fended off infection by influenza A virus, but almost half of the cells in a control group became infected.
Many relatives of B. fragilis have membrane molecules that prompt a similar response, the authors say.