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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

Stem cell research and human cloning: legal and ethical focal points

2004-07-29

(Summary of the inaugural lecture of Prof Hennie Oosthuizen, from the Department of Criminal and Medical Law at the Faculty of Law of the University of the Free State.)

In the light of stem cell research, research on embryo’s and human cloning it will be fatal for legal advisors and researchers in South Africa to ignore the benefits that new bio-medical development, through research, contain for this country.

Legal advisors across the world have various views on stem cell research and human cloning. In the USA there is no legislation that regulates stem cell research but a number of States adopted legislation that approves stem cell research. The British Parlement gave permission for research on embryonic stem cells, but determined that it must be monitored closely and the European Union is of the opinion that it will open a door for race purification and commercial exploitation of human beings.

In South Africa the Bill on National Health makes provision for therapeutical and non therapeutical research. It also makes provision for therapeutical embryonical stem cell research on fetuses, which is not older than 14 days, as well as for therapeutical cloning under certain circumstances subject to the approval of the Minister. The Bill prohibits reproductive cloning.

Research on human embrio’s is a very controversial issue, here and in the rest of the world.

Researchers believe that the use of stem cell therapy could help to side-step the rejection of newly transplanted organs and tissue and if a bank for stem cell could be built, the shortage of organs for transplants would become something of the past. Stem cells could also be used for healing of Alzheimer’s, Parkinson’s and spinal injuries.

Sources from which stem cells are obtained could also lead to further ethical issues. Stem cells are harvested from mature human cells and embryonic stem cells. Another source to be utilised is to take egg cells from the ovaries of aborted fetuses. This will be morally unacceptable for those against abortions. Linking a financial incentive to that could become more of a controversial issue because the woman’s decision to abort could be influenced. The ideal would be to rather use human fetus tissue from spontaneous abortions or extra-uterine pregnancies than induced abortions.

The potential to obtain stem cells from the blood of the umbilical cord, bone-marrow and fetus tissue and for these cells to arrange themselves is known for quite some time. Blood from the umbilical cord contains many stem cells, which is the origin of the body’s immune and blood system. It is beneficial to bank the blood of a newborn baby’s umbilical cord. Through stem cell transplants the baby or another family member’s life could be saved from future illnesses such as anemia, leukemia and metabolic storing disabilities as well as certain generic immuno disabilities.

The possibility to withdraw stem cells from human embrio’s and to grow them is more useable because it has more treatment possibilities.

With the birth of Dolly the sheep, communities strongly expressed their concern about the possibility that a new cloning technique such as the replacement of the core of a cell will be used in human reproduction. Embryonic splitting and core replacement are two well known techniques that are associated with the cloning process.

I differentiate between reproductive cloning – to create a cloned human embryo with the aim to bring about a pregnancy of a child that is identical to another individual – and therapeutically cloning – to create a cloned human embryo for research purposes and for healing human illnesses.

Worldwide people are debating whether to proceed with therapeutical cloning. There are people for and against it. The biggest ethical objection against therapeutical cloning is the termination of the development of a potential human being.

Children born from cloning will differ from each other. Factors such as the uterus environment and the environment in which the child is growing up will play a role. Cloning create unique children that will grow up to be unique individuals, just like me and you that will develop into a person, just like you and me. If we understand this scientific fact, most arguments against human cloning will disappear.

Infertility can be treated through in vitro conception. This process does not work for everyone. For some cloning is a revolutionary treatment method because it is the only method that does not require patients to produce sperm and egg cells. The same arguments that were used against in vitro conception in the past are now being used against cloning. It is years later and in vitro cloning is generally applied and accepted by society. I am of the opinion that the same will happen with regard to human cloning.

There is an argument that cloning must be prohibited because it is unsafe. Distorted ideas in this regard were proven wrong. Are these distorted ideas justified to question the safety of cloning and the cloning process you may ask. The answer, according to me, is a definite no. Human cloning does have many advantages. That includes assistance with infertility, prevention of Down Syndrome and recovery from leukemia.

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