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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

Help to rural women to become entrepreneurs

2006-10-24

Some of the guests who attended the ceremony were, from the left: Mr Donray Malabie (Head of the Alexander Forbes Community Trust), Ms Jemina Mokgosi (one of the ladies from Tabane Village who is participating in the Women in Agriculture project), Dr Limakatso Moorosi (Head: Veterinary Services, Free State Department of Agriculture), Prof Johan Greyling (Head: UFS Department of Animal and Wildlife and Grassland Sciences) and Ms Khoboso Lehloenya (coordinator of the project from UFS Department of Animal and Wildlife and Grassland Sciences). Photo: Leonie Bolleurs\

Alexander Forbes and UFS help rural women to become entrepreneurs

Today, the Alexander Forbes Community Trust and the University of the Free State (UFS) joined forces to create an enabling environment for rural women to become players in the private sector.

Three years ago the UFS set up a unique small-scale household egg production project called Women in Agriculture in Thaba ‘Nchu as a pilot project. The project was officially launched today by Mr Donray Malabie, Head of the Alexander Forbes Community Trust.

The aim of the Women in Agriculture Project is to create jobs, provide food security and to help develop rural women into entrepreneurs. A total of 25 women based in Tabane Village in Thaba ‘Nchu are the beneficiaries of the project.

“This is the first project in the Free State the Alexander Forbes Community Trust is involved with. The project would help rural women acquire the skills they need to run their own egg-production business from their homes,” said Mr Malabie.

“The ongoing debate on the shortage of skills ignores the fact that people with little or no education at all also need training. This project is special to the Trust as it provides for the creation of sustainable jobs, food security and the transfer of much needed skills all at once, particularly at this level,” he said.

Every woman in the group started with two small mobile cages that housed 12 hens each. The units are low in cost, and made of commercially available welded mesh and a metal frame. Now, each woman has four cages with 48 hens. The group manages to collectively produce 750 eggs daily.

The eggs are currently sold to local businesses, including spaza shops and the women are using the income generated to look after their families and to further develop their business.

The Department of Animal and Wildlife and Grassland Sciences at the UFS identified the project and did the initial research into the feasibility of setting up such a project.

“A demonstration and training unit has been established at the Lengau Agricultural Development Centre and the women attended a short practical training course. Subsidies are provided for feeding, together with all the material and the lay hens necessary for the start of the business,” said Ms Khoboso Lehloenya, coordinator of the project from the Department of Animal and Wildlife and Grassland Sciences at the UFS.

“The advantage in using lay hens is that they are resistant to diseases and the women will not need electric heating systems for the egg production,” said Ms Lehloenya.

According to Ms Lehloenya, the women are already benefiting from their egg production businesses. “Some of them have used the profit to buy school uniforms and tracksuits for their children and others are now able to make a monthly contribution to their household expenses,” said Ms Lehloenya.
“In South Africa, possibly due to cultural reasons and circumstances, most black people prefer to eat older and tougher chickens, compared to younger soft commercially available broiler chickens. This preference creates a further advantage for the women. At the end of their production cycle, old hens can be sold for a higher price than point-of-lay or young hens. This brings in further money to pay for more hens,” said Ms Lehloenya.

The Alexander Forbes Trust contributed R191 000 towards the project aimed at expanding it to benefit 15 more women.

“We are in the process of recruiting an additional 15 women in Thaba ‘Nchu who will be trained by the Lengau Agricultural Development Centre in order to replicate the model and extend its reach”, said Ms Lehloenya.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl@mail.uovs.ac.za
20 October 2006

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