Category Environment/Geology

Annual mean heatwave degree days in Belgium. Historical on the left, and under business-as-usual climate change scenario on right. Not only the number of hot days days, but also the heatwave intensity are rising drastically under global warming, especially in the cities.

Heatwaves are intensifying in cities due to the double whammy of the urban heat island effect and global warming, according to a new study. The study’s authors used computer models to simulate with unprecedented detail the temperature changes through the mid-21st century in Belgian cities. They found that heatwaves become hotter, longer and more frequent because of greenhouse gas emissions, and that temperature above the heat stress alarm level increases by a factor of between 1.4 and 15 by the middle of this century.

“The...

An artist’s depiction of the promise of carbon nanotube porins for desalination. The image depicts a stylized carbon nanotube pipe that delivers clean desalinated water from the ocean to a kitchen tap. Credit: Image by Ryan Chen/LLNL

Lawrence Livermore scientists, in collaboration with Northeastern University have developed a saltwater purification device. The team also found that water permeability in carbon nanotubes (CNTs) with diameters smaller than a nanometer (0.8 nm) exceeds that of wider CNTs by an order of magnitude. The nanotubes, hollow structures made of carbon atoms in a unique arrangement, are more than 50,000 times thinner than a human hair...

Artist’s rendering of bioreactor (left) loaded with bacteria decorated with cadmium sulfide, light-absorbing nanocrystals (middle) to convert light, water and carbon dioxide into useful chemicals (right). Credit: Kelsey K. Sakimoto

Photosynthesis provides energy for the vast majority of life on Earth. But chlorophyll, the green pigment that plants use to harvest sunlight, is relatively inefficient. To enable humans to capture more of the sun’s energy than natural photosynthesis can, scientists have taught bacteria to cover themselves in tiny, highly efficient solar panels to produce useful compounds. “Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Kelsey K. Sakimoto, Ph.D....

This diagram depicts a new reaction mechanism that could be used to improve catalyst designs for pollution-control systems for diesel exhaust.
Credit: Purdue University photo/Maureen Lifton

Researchers have discovered a new reaction mechanism that could be used to improve catalyst designs for pollution control systems to further reduce emissions of smog-causing nitrogen oxides in diesel exhaust. The research focuses on a type of catalyst called zeolites, workhorses in petroleum and chemical refineries and in emission-control systems for diesel engines. New catalyst designs are needed to reduce the emission of nitrogen oxides, or NOx, because current technologies only work well at relatively high temperatures.

“The key challenge in reducing emissions is that they can occur over a very broad ...