New Worlds: Nano-precision microscope developed in Beersheba

The microscope is based on what is termed parallel-phase shift interferometry, which allows for three-phase images to be obtained simultaneously.

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December 3, 2017 00:53
4 minute read.
A scientist looks through a microscope

A scientist looks through a microscope. (photo credit: INGIMAGE)

A fast 3D optical microscope with a full-field image of the surfaces of objects at nanoscale resolution was developed recently in the lab of Prof. Ibrahim Abdulhalim in the electro-optical engineering unit at Ben-Gurion University of the Negev in Beersheba.

The microscope is based on what is termed parallel-phase shift interferometry, which allows for three-phase images to be obtained simultaneously and extraction of the height topography map in a simple algebraic computation.

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Based on the same principle, the researchers showed vibration measurements with amplitudes ranging from one nanometer to tens of microns with sub-nm resolution. The microscope emerged from the doctoral and post-doctoral work of Dr.

Avner Safrani followed by Dr. Michael Ney’s post-doctoral work.

Results of the research were recently published in some leading optics journals such as Optics Letters and were among the top downloaded papers during the month of publication.

Based on the interference phenomenon of light waves, it is possible in principle to measure displacements with precision of less than the radius of an atom. A good example of this was the historic event in February 2016 when researchers succeeded, using the LIGO interferometer, to measure gravitational waves originating from far away objects in space for the first time. The Nobel Prize in Physics was just awarded to three researchers who played a key role in LIGO’s development.

“In response to the request from the optical metrology companies, we arrived at a speed faster by two orders of magnitude than what they asked for, and with sub-nm precision.

The next step in the research is to build the microscope and the vibrometer compactly and develop biological applications that will allow imaging of cell profiles quickly with nano-precision without the need for fluorescent staining. The high speed and precision will help biologists to follow dynamic processes in short time scales, while determining cell profile with nano-precision will help in diagnosing diseases such as cancer at early stages,” concluded Abdulhalim.

MOUTH CLICKS USED IN HUMAN ECHOLOCATION
Like some bats and marine mammals, people can develop skills in echolocation in which they produce a clicking sound with their mouths and listen to the reflected sound waves to “see” their surroundings. A new study recently published in PLOS Computational Biology provides the first in-depth analysis of the mouth clicks used in human echolocation.

The research, performed by Lore Thaler of Durham University, Galen Reich and Michael Antoniou of Birmingham University and other colleagues in the UK, focuses on three blind adults who have been expertly trained in echolocation. Since the age of 15 or younger, all three have used the technique in their daily lives. They use the technique for such activities as hiking, riding bicycles and visiting unfamiliar cities.

While the existence of human echolocation is well documented, the details of the underlying acoustic mechanisms have been unclear. In the new study, the researchers set out to provide physical descriptions of the mouth clicks used by each of the three participants during echolocation. They recorded and analyzed the acoustic properties of several thousand clicks, including the spatial path the sound waves took in an acoustically controlled room.

Analysis of the recordings revealed that the clicks made by the participants had a distinct acoustic pattern that was more focused in its direction than that of human speech. The clicks were brief – around three milliseconds long –and their strongest frequencies were between two to four kilohertz, with some additional strength around 10 kilohertz.

The researchers also used the recordings to propose a mathematical model that could be used to synthesize mouth clicks made during human echolocation. They plan to use synthetic human clicks to investigate how these sounds can reveal the physical features of objects; the number of measurements required for such studies would be impractical to ask from human volunteers.

“The results allow us to create virtual human echolocators,” Thaler said. “This allows us to embark on an exciting new journey in human echolocation research.”

NITTY-GRITTY BEHIND HOW ONIONS MAKE YOU CRY
Did you ever wonder why onions make you tear when you cut them up? Adding onions to a recipe can make a meal taste rich and savory, but cutting up the onion can be brutal.

Onions release a compound called lachrymatory factor (LF), which makes the eyes sting and water. Scientists know that a certain enzyme causes this irritating compound to form but precisely how it helps LF form in the onion remained an open question. Now, one group reports in ACS Chemical Biology that they have the answer.

According to the National Onion Association, the average American consumes nine kilos of onions each year. When an onion is cut, it has a natural defense mechanism that springs into action, producing LF. This kind of compound is rare – only four known natural types exist. An enzyme in the onion known as lachrymatory factor synthase (LFS) spurs production of LF in the onion. “Tearless” onions, sold exclusively in Japan for a hefty price, don’t make LFS, so they also don’t produce the irritant LF. But scientists have been at a loss to explain exactly how LFS helps LF form. That’s because it is extremely reactive, and LF evaporates or breaks down easily. Marcin Golczak and colleagues wanted to take a different approach to solve this mystery once and for all.

The team determined the crystal structure of LFS and analyzed it. With the crystal structure, they could finally see the architecture of the enzyme as a whole and its active site as it bound to another compound. By combining this information with known information about similar proteins, the group developed a detailed chemical mechanism that could explain the precise steps involved in LF synthesis – and hence, why people wind up crying when they chop an onion.


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