2019-11-23 New Scientist

18 | New Scientist | 23 November 2019

Disease

Moving holograms

that you can touch

IT IS possible to create a 3D moving

image using nothing but a tiny

polystyrene ball and speakers.

Ryuji Hirayama at the

University of Sussex, UK, and his

colleagues built the device using

512 speakers, positioned above and

below a small 3D stage that acts as

an image display. The speakers

emit silent ultrasound to create

small pockets of low air pressure

in which the polystyrene ball

Minute nutrient pods

could tackle poor diet

TINY particles packed with vital

nutrients could provide a better

way of delivering supplements to

people at risk of malnutrition. The

particles protect their contents

from moisture and resist heat

during cooking before breaking

down in the stomach.

Some 2 billion people globally

have nutrient-deficient diets. This

is the leading cause of cognitive

and physical disorders in the

developing world, according to an

international team of researchers

led by Ana Jaklenec and Robert

Langer at the Massachusetts

Institute of Technology.

A major challenge in adding

nutrients to food is that many are

destroyed by the heat of cooking

or add a bad taste to dishes, the

pair say. Their team has overcome

these issues by trapping nutrients

inside small, protective particles

that can be added to food.

Malnutrition^ Technology

TWEAKING the rabies vaccine could

lead to more effective and cheaper

treatment that may save some of

the 60,000 people killed by the

disease each year.

More than two in three

people live in areas where

rabies is endemic. Something

as simple as a dog bite – dogs

account for around 99 per cent of

infections – can transmit the virus,

but symptoms may not emerge for

weeks. If an infected person hasn’t

received treatment by then, death

is virtually inevitable.

Unfortunately, the vaccines used

both to prevent infection and to

treat someone with rabies are costly

and need multiple rounds to work,

which is an issue in poorer nations.

This prompted James McGettigan

at Thomas Jefferson University in

Pennsylvania and his colleagues

to search for a better treatment.

Current vaccines use the inactive

virus to trigger B cells in the body.

B cells remember the virus and

make antibodies against it to fight

any subsequent infection. The team

modified this vaccine by attaching

an extra protein to the surface of

the inactive virus, one that binds

directly to B cells and alerts them to

the existence of the pathogen more

quickly than the old vaccine does.

When the researchers tested this

vaccine on mice, they found that the

levels of antibodies in their blood

jumped quicker and higher than in

mice given the old vaccine. Within

five days, mice who had the new

vaccine had twice the level of

antibodies in their blood of the

other mice (PLoS Neglected

Tropical Diseases, doi.org/dd7x).

Ruby Prosser Scully

Improved rabies vaccine

could save more lives

floats. By manipulating the sound

waves, they can rapidly shift the

precise 3D position of the low-

pressure pockets, and so control

the position of the ball.

If the bead moves fast enough,

it traces out what appears to the

viewer to be a 3D shape, and it is

even possible to change the form

of that shape over time to give the

impression of a moving 3D object.

All this has to happen extremely

quickly. The 3D shape has to be

traced out in full in less than

0.1 seconds – any slower and

the visual effect is lost.

It is possible to add colour to the

3D objects by directing beams of

red, green and blue light onto the

bead. In one demonstration, the

system shows a butterfly flapping

its wings (pictured). People are

also able to touch the image. This

works because the speakers create

an area of higher pressure air

surrounding the bead. When your

fingers contact it, it feels like you

are touching the 3D object (Nature,

doi.org/dd72). Gege Li

The microscopic particles

measure less than a quarter of a

millimetre across and can package

11 different nutrients individually,

or combinations of up to four

nutrients together. They are

made of a material that is resistant

to heat, light and moisture, but

disintegrates when exposed to

stomach acid, ensuring that the

nutrients inside are released

and absorbed by the gut.

The researchers baked

particles containing iron into

bread, which was then eaten

by 24 volunteers. Almost three

weeks after eating the bread,

iron levels in their blood were

equivalent to levels detected

after they had a conventional iron

supplement (Science Translational

Medicine, doi.org/dd73).

Giuseppe Battaglia at University

College London says the approach

could have applications beyond

delivering nutrients: it may also

be possible to encapsulate some

therapeutic drugs using the

particles. Layal Liverpool

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