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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

Multi-disciplinary research approach at UFS

2005-10-25

UFS follows multi-disciplinary research approach with opening of new centre

“A new way of doing business in necessary in the research and teaching of agriculture and natural sciences in South Africa. We must move away from departmentalised research infrastructures and a multi-disciplinary approach to research involving several disciplines must be adapted,” said Prof Herman van Schalkwyk, Dean: Faculty of Natural and Agricultural Sciences at the University of the Free State (UFS).

Prof van Schalkwyk delivered the keynote address during the launch of the Centre for Plant Health Management (CePHMa) at the Main Campus in Bloemfontein today (21 October 2005). CePHMa is an initiative of the UFS Department of Plant Sciences.

According to Prof van Schalkwyk a tertiary institution must practice multi-disciplinary research to be a world-class research institution. “It is difficult for researchers to admit that they do not know a lot about each other’s area of speciality. It is therefore necessary for researchers to make a paradigm shift and to focus on inter-disciplinary co-operation. To do this, we must encourage them to work together and to find a common language to communicate ideas en establish symbiotic relationships,” said Prof Van Schalkwyk.

“We tend to think that research is better and faster if it is specialised. This is not true. The new generation of scientists are young and they are trained to form a concept of the total system and not to focus on a specific area of speciality. At the UFS we encourage this approach to research. This was one of the main reasons for the establishment of CePHMa,” said Prof Van Schalkwyk.
CePHMa is the only centre of its kind in Africa and is established to extend the expertise in plant health management in South Africa and in Africa, to train experts in plant health and to conduct multi-disciplinary research about the health of agricultural crops.

“CePHMa is a virtual centre comprising of ten disciplines applicable to crop production and crop protection,” said Prof Wijnand Swart, Chairperson of CePHMa during the opening ceremony.

“The UFS is the leading institution in Africa in terms of news crop development and manages three research programmes that concentrate on new crops, i.e. the New Crop Pathology Programme, the New Crop Development Programme and the Insects on New Crops Programme. Other applied research programmes that are unique to the UFS are genetic resistance to rust diseases of small grain crops and sustainable integrated disease management of field crops,” said Prof Swart.

“Because the expected growth in population will be 80% in 2020 in sub-Saharan Africa, the future demands of food produce in Africa will be influenced. Therefore research will in future be focused on ways to improve food security by employing agricultural systems that are economically viable and environmentally sound,” said Prof Swart.

“Thorough knowledge of the concept of holistic plant health management is crucial to meet the challenge and it is therefore imperative that innovative crop protection and crop production strategies, with particular emphasis on plant health, be adopted. This is why the Department of Plant Sciences initiated the establishment of CePHMA,” he said.

According to Prof Swart there is a shortage of expertise in plant health management. “The UFS has shown the potential to address the demand of the sub-continent of Africa regarding expertise training and CePHMa is the leader in southern Africa to provide in this need,” he said.

The appropriateness and quality of training in plant health management is reflected in the fact that students from Ethiopia, Eritrea, Malawi, Uganda, Zambia, Ghana, Tanzania, Cameroon, Angola, Mozambique and Lesotho have already been trained or are in the process of being trained in at the UFS.

Scientists from CePHMa have forged partnerships with numerous national and international institutions including the Agricultural Research Council (ARC), various community trusts, seed, pesticide and agricultural chemical companies, in addition to overseas universities.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
21 October 2005

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