Category Environment/Geology

The polarized light reflected from the leaf contains a footprint of the leaf’s biopigments. These biosignatures can be detected with a polarization filter, shown here as a pair of sunglasses. Credit: Illustration: Svetlana Berdyugina

Biopigments of plants, so-called biological photosynthetic pigments, leave behind unique traces in the light they reflect, an international team has discovered. The scientists studied these biosignatures with the help of polarization filters: If biopigments were present as a sign of life on a planet, they would leave behind a detectable polarized signature in the reflected light.

Eg Chlorophyll pigments in plant leaves, absorb blue to red light but reflect a small part of green in the visible spectrum and thus appear green...

A rock fulgurite revealed that lightning strikes alter quartz’s crystal structure on the atomic level.

Researchers once believed only meteorites could do so. At a rock outcropping in southern France, a jagged fracture runs along the granite. The surface in and around the crevice is discolored black, as if wet or covered in algae. But the real explanation for the rock’s unusual features is more dramatic: a powerful bolt of lightning.

Using extremely high-resolution microscopy, Prof Gieré et al found that not only had the lightning melted the rock’s surface, resulting in a distinctive black “glaze,” but had transferred enough pressure to deform a thin layer of quartz crystals beneath the surface, resulting in distinct atomic-level structures called shock lamellae...

Walking on water might sound supernatural, but in fact it is a quite natural phenomenon. Many small creatures use water’s surface tension to maneuver around. One of the most complex maneuvers, jumping on water, is achieved by a species of semi-aquatic insects called water striders that not only skim along water’s surface but also generate enough upward thrust with their legs to launch themselves airborne from it.

Now, emulating this natural form of water-based locomotion, an international team of scientists from Seoul National University (SNU), Harvard’s Wyss Institute for Biologically Inspired Engineering, and Harvard John A. Paulson School of Engineering and Applied Sciences, has unveiled a novel robotic insect that can jump off of water’s surface...

Hierarchical structure of wood fibers and the characteristic of cellulose fibrils. Note the rich interchain hydrogen bonds among neighboring cellulose molecular chains.

Paper made of cellulose fibers is tougher and stronger the smaller the fibers get. For a long time, engineers have sought a material that is both strong (resistant to non-recoverable deformation) and tough (tolerant of damage). “Strength and toughness are often exclusive to each other,” said Teng Li, associate professor of mechanical engineering at UMD. “For example, a stronger material tends to be brittle, like cast iron or diamond.”

The UMD team pursued the development of a strong and tough material by exploring the mechanical properties of cellulose, the most abundant renewable bio-resource on Earth...