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TED Talks about rainbows

18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett

“A rainbow is a natural phenomenon, the result of the refraction and reflection of the sun’s rays in drops of rain. As far as mankind is concerned, it’s a perfectly useless object and won’t make anyone money. Yet the poet who said, My heart leaps up when I behold a rainbow in the sky, only put into word the feeling of wonder and excitement we all have when we see a rainbow.”

“Every day I see a rainbow in my work; I do not need to wait to see one in the sky,” says Prof Ted Kroon, Professor in the Department of Physics at the University of the Free State (UFS), who used this phenomenon to introduce the topic of his inaugural lecture: What’s the use of a rainbow.

“Far from being only a colourful spectacle with no practical value, rainbows are useful – and lead to useful things,” he believes.

According to Prof Kroon, one can find examples of real rainbows and rainbow analogies used not only in everyday life, but also in physics. “Besides it being familiar devices in literature, culture, and even marketing, studies of rainbows can yield practical engineering information and may even help us to find new habitable planets,” he says.

Inspired by the many uses of a rainbow

In his lecture, he discussed the basic features of natural rainbows and how they come about. He also explored how the rainbow gives meaning to colour, and how this relates to the temperature of objects. He looked at an array of instances where the rainbow is used; from depicting the life of a star to indicating that we are sick (a thermometer) or when we need to refill a gas cylinder.

Moreover, Prof Kroon pointed out that rainbows are used in computer chips, stress identification, and to transmit internet data through underwater cables of glass fibre. He also referred to how the rainbow was harnessed as an engineering tool to measure refractive index and characterise fine droplet sprays used in industry.

He continues, “Remarkably, the science developed to understand the natural rainbow can be redirected and applied to the optical properties of metallic nanoparticles, allowing the development of nanotechnology. Knowing how the natural rainbow works and its limitations, better systems have been developed to produce rainbows. Such rainbows have been used to discover new elements and to determine the age of the universe.”

As a member of an international community of phosphor researchers who are privileged to work with rainbows every day, he has used them to study the light-emitting properties of materials doped with bismuth. With this project – an initiative with the African Laser Centre taking place between 2016 and 2021 – he collaborated with the University of Khartoum in Sudan and trained a number of its postgraduate students. “My role included the guidance of students and the measurement and interpretation of the light-emitting properties of the materials. Our research during this time, considering more than a dozen materials, was summarised in 34 scientific publications that contributed to a greater understanding of bismuth ions as light-emitting materials,” he explains.

Developing new materials, efficient in emitting blue light

He has been developing luminescent materials since 2006, primarily for general lighting (fluorescent tubes and LEDs) and displays (television, computer, and cellphone screens), as well as niche applications in medical and forensic science.

As part of his current research, he is examining the effect of plasmonic metal nanoparticles on phosphor light emission. He is also exploring materials that absorb infrared light but emit visible light. “For this, I would like to consider the long-term stability of such materials and develop new materials that are more efficient in emitting particularly blue light,” he says.

Prof Kroon holds a C2 rating from the National Research Foundation and has published more than 150 articles and book chapters, obtaining a Scopus h-index of 26.

News Archive

UFS responds on the outcome of the court case in the alleged attack by Cobus Muller and Charl Blom on Gwebu

2014-09-09

The management of the University of the Free State (UFS) acknowledges the finding issued on 4 September 2014 by the South African Human Rights Commission (SAHRC) that it was “unable to find any corroborating evidence to make a conclusive finding of racism and violation of human rights” in the Muzi Gwebu case.

The university management also takes cognisance of the ruling in the Bloemfontein Regional Court by Regional Magistrate Rasheed Matthews today (9 September 2014) that both Cobus Muller and Charl Blom are found not guilty on all the charges which included reckless driving, crimen injuria, attempted murder and assault (Muller), and a charge of assault (Blom). We note the Magistrate’s concerns about “inconsistencies in the evidence and exaggerations”, that the complainant “displayed hostility throughout the trial” and that he was “not a reliable witness and is prejudiced.” And therefore, in the words of the Magistrate to the defendants, “I’ve decided to give you the benefit of the doubt.”

Both Muller and Blom were suspended from all campuses of the UFS on 19 February 2014 based on the evidence available at the time of reckless driving, assault and other charges. This evidence was further borne out by an internal investigation into the incident of 17 February 2014 on the Bloemfontein Campus. In the light of the evidence available to us at the time, and the volatile situation on campus in the days following the attack, the UFS management believes that it was the correct decision to suspend the students, given the serious nature of the charges, and pending a decision of the courts.

In the light of both the SAHRC ruling as the Regional Court ruling, the university management has decided to take the following steps:

1.   The suspensions of both Muller and Blom from all campuses of the university are lifted with immediate effect.

2.   Muller may attend a forthcoming graduation ceremony during which the degree BSc Construction Management will be officially conferred upon him. He completed all the requirements for the degree in 2013, but was not allowed to attend the graduation ceremony of 11 April 2014 due to his suspension and the fact that the criminal charges were still pending.

3.   Blom may return to the university to complete his studies.

4.   The UFS is in discussion with the parents of one of the students and, if required, would also meet with legal counsel of the university, as well as those of students Muller and Blom to discuss any further steps given the outcome of the court case.

5.   In short, on grounds of the ruling by die SAHRC, as well as the Bloemfontein Regional Court, the university will not continue with its disciplinary action against Muller and Blom.

Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS said: “This has been a very difficult time for the university and I am pleased to record that throughout the crisis, the student body on the Bloemfontein Campus showed remarkable restraint and discipline, confirming also the broad, non-racial character of the peaceful protests that followed. Our student body has matured and our campus cultures are much more inclusive and transformed as a result of the quality and depth of student leadership over the past few years. The new Student Representative Council (SRC) is a splendid example of this – with the first black woman President (Mosa Leteane) and the first blind woman SRC student leader (Louzanne Coetzee).”

“I am pleased that the matter is now behind us and, again, we rest with the decisions of the Commission and the Courts as final,” he said.

Prof Jansen also apologised on behalf of the UFS to Cobus Muller and Charl Blom, their parents, and their families, for the disruption that the suspension brought in their lives and for the stress they had to bear during this difficult period. “For that, I am truly sorry,” he said.

Issued by: Lacea Loader (Director: Communication and Brand Management)
Tel: +27 (0) 51 401 2584 | +27 (0) 83 645 2454
E-mail: news@ufs.ac.za

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