Science - USA (2021-12-10)

microscope, the researchers

were able to map out this Fermi

surface. —JS

Science, abf1077, this issue p. 1381

OPTICAL IMAGING

A view through a fiber

Reconstructing a three-dimen-

sional (3D) image of a scene

typically involves sending out

pulses of light and timing their

return. For endoscope applica-

tions in bioimaging or imaging

inside difficult-to-reach places

inside machines, the typical

approach using bulk optics

may not be viable. Stellinga et

al. found that 3D imaging can

be achieved using multimode

optic fibers. After character-

izing the transmission matrix

of the fiber, optical pulses can

be used to reconstruct 3D

images of a number of scenes.

Because this approach can use

fibers the width of a human

hair, the results are promising

PLANT SCIENCE

Shared systems

in leaf development

The long, narrow leaves of

grasses look rather different

from the often shorter, flat-

ter leaves of eudicot plants.

Richardson et al. combined

developmental genetics and

computational modeling to

reveal that these two types

of leaves, which are widely

separated by evolution, have

more in common than expected.

Expression of similar patterning

genes in the primordial zone

is confined to a wedge for the

eudicot leaf but expanded to

concentric domains in the grass

leaf, driving development of the

cylindrical, encircling sheath

characteristic of these leaves.

Addition or removal of gene

expression in a marginal zone

contributes to the development

of the broader leaf characteris-

tic of eudicots. Thus, grass and

eudicot leaves are diversified

elaborations of shared toolkits.

— PJ H

Science, abf9407, this issue p. 1377

GRAPHENE

Detecting orbital

magnetism

Graphene’s electronic structure

has been predicted to lead to

an unusual orbital response

to magnetic fields. However,

detecting this orbital magne-

tism is difficult because it is

usually masked by the signal

stemming from spins. Vallejo

Bustamante et al. managed to

capture this response by placing

two giant magnetoresistance

detectors below a sample of

graphene sandwiched by layers

of hexagonal boron nitride.

These detectors picked up a

strong diamagnetic response

from an undoped sample,

consistent with theoretical

predictions. The technique may

be useful in the investigation of

other two-dimensional materi-

als. —JS

Science, abf9396, this issue p. 1399

SUPERCONDUCTIVITY

Imaging a peculiar

Fermi surface

Running a current through a

superconductor can cause

the superconducting gap to

close on a section of the Fermi

surface. However, observing

this segmented Fermi surface

directly is tricky. To do so, Zhu

et al. worked with a thin film

of the topological insulator

bismuth telluride placed on top

of superconducting niobium

diselenide. A small applied

magnetic field caused a screen-

ing current, which in turn led to

a segmented Fermi surface in

the topological insulator layer.

Using a scanning tunneling

RESEARCH

IN SCIENCE JOURNALS

PHOTO: TURTLE ROCK SCIENTIFIC/SCIENCE SOURCE

SCIENCE science.org 10 DECEMBER 2021 • VOL 374 ISSUE 6573 1335

HYDROPHOBICITY

Why oil and water do not mix

I

t is well known that oil forms stable droplets that carry a negative

electrophoretic mobility (and negative charge) upon dispersing

in water. However, the underlying mechanism is a long-debated

topic. Using vibrational sum-frequency scattering spectroscopy,

Pullanchery et al. recorded the interfacial vibrational spectrum in

the oxygen–deuterium and carbon–hydrogen stretching regions of a

hexadecane–water interface. Their spectral analysis accompanied by

molecular dynamics simulations showed that water molecules form

“improper” interfacial hydrogen bonds with alkyl hydrogens, resulting

in the water-to-oil charge transfer that stabilizes oil droplets. This

work demonstrates that sum-frequency scattering spectroscopy is a

powerful technique that can improve our understanding of hydro-

phobicity in water-mediated chemical and biological systems. —YS

Science, abj3007, this issue p. 1366

Edited byMichael Funk

Oil and water mixtures form stable droplets in part due to “improper” hydrogen

bonds between water molecules and the alkyl chains of oil.