Reading Exercise: The Dangers of Radioactivity

Radioactive radiation

Radioactive radiation is dangerous because it is ionizing. This means that it has enough energy to knock electrons out of their shells and thus turn atoms into ions.

A large amount of ionizing radiation can cause radiation burns (skin burns) and radiation sickness. Small amounts of ionizing radiation can damage DNA. This is called mutation and can later lead to cancer. If mutations occur in gametes (sex cells), they can be passed on to the next generation and can cause birth defects in newborns.

Protection from radiation

We are exposed to background radiation all the time. However, the amount is too small to harm us. But people who work with radioactive materials are exposed to more radiation and need to take precautions.

There are three ways to limit the effects of ionizing radiation: keeping a distance from the source, shielding and a time limit to exposure. For example, radioactive samples are always handled with tongs to keep a distance and stored in containers with thick lead walls for shielding.

Ionizing radiation is also used in hospitals to detect and treat cancer. Patients can be exposed to small amounts of radiation during their treatment. However, this is only done if the benefits are greater than the risks.

Irradiation and contamination

Sometimes there are accidents in nuclear power stations which can lead to radioactive materials escaping to the environment. This can lead to the irradiation and contamination of plants, animals and people. It is important to understand the difference between irradiation and contamination.

Someone is irradiated if they are close to a radioactive material and exposed to its radiation. Once the person moves away the irradiation stops.

Someone is contaminated if they get particles of radioactive material on their skin or inside their body, for example by eating or breathing. This person continues to be exposed to the radiation until all the material has decayed inside their body.

Things to do

  1. What is ionizing radiation?
  2. Give four effects of ionizing radiation on the human body.
  3. Why is background radiation not dangerous for us?
  4. State three ways to protect yourself from radiation.
  5. Why are radioactive samples handled with tongs and kept in lead containers with thick walls?
  6. What is the difference between irradiation and contamination?
  7. In case of a nuclear accident, what is worse? Irradiation or contamination? Why?
  8. Do you know any examples of nuclear accidents that have happened around the world? If yes, which do you know?

How to make your own terrarium

This activity is easy to do at home with children of any age.

You will need the following:

  • Soil
  • Moss
  • Water (ideally from a stream or pond outside, but tap water will do also)
  • Glass jar
  • Stones (just a few)

What to do:

  1. Collect what you need during a walk.
  2. Fill the glass jar first with the soil.
  3. Then add the stones.
  4. Next add the moss.
  5. Finally add some water. The moss likes it humid, but be careful not to drown it.
  6. Close the jar with the lid.
  7. Observe your biosphere carefully over the next couple of days.

Active reading exercise: Isotopes

Isotopes

In 1932 James Chadwick, a British scientist, discovered the neutron. His discovery explains how isotopes are formed. Isotopes have the same number of protons, but different numbers of neutrons.

We can also say that the atomic number is the same, but the mass numbers are different. Isotopes are the same element because their atomic number does not change.

We refer to an isotope by adding its mass number to the element’s name. The isotope in the diagram below is called carbon-12.

carbon

Carbon isotopes

Carbon can occur as three different isotopes. They are called carbon-12, carbon-13 and carbon-14.

Carbon dating is used to identify the age of very old objects, for example the remains of extinct animals such as mammoths. The amount of the carbon isotope carbon-14 in an object is examined to determine its age.

Things to do

  1. Fill in the missing words and numbers to describe the similarities and differences between isotopes of the same element.                                                                                 a) Isotopes are atoms with the same            number but different                   number. b) They have the same number of protons and electrons but different numbers of                      .
  2. Name the scientist who discovered the neutron.
  3. Why are isotopes the same element?
  4. How do we refer to isotopes?
  5. Name the three isotopes of carbon.
  6. Why is the isotope carbon-14 useful?
  7. Using your knowledge about isotopes, fill in the gaps in the table a, b and c.
Isotope name Atomic number Mass number
 Tin-116  50 a
b c 118

Remember that the atomic number is the same for isotopes of the same element.

Active reading exercise: The Atom

A bit of history

In 1805 the English Chemist John Dalton published his atomic theory that said:

  • Everything is made up from tiny particles called atoms
  • Atoms are tiny hard spheres (= balls) that cannot be broken down into smaller parts
  • Atoms in one element are all identical

This helped to explain many properties of materials. However, later experiments showed that atoms contained even smaller particles. In 1897 another British scientist, JJ Thomson, discovered the electron. The nucleus which makes up the middle of an atom was discovered by Ernest Rutherford in 1913.

The Structure of the atom

Today we know that atoms are made from three subatomic particles: proton, neutron and electron.

Protons and neutrons are found in the centre of the atom which is called the nucleus. Both have a mass of 1. Protons have a positive (+) charge and neutrons are neutral (= no charge).

Electrons have a negative (-) charge and have almost no mass at all. They are found on the electron shells on the outside of the atom, circling the nucleus.

What you need to remember

  • Atoms are made from protons, neutrons and electrons called subatomic particles
  • Protons: found in nucleus, positive (+) charge and a mass of 1
  • Neutrons: found in nucleus, neutral (no charge) and a mass of 1
  • Electrons: found on electron shells, negative (-) charge and almost no mass

 

Things to do

  1. Name the scientist who first introduced atomic theory.
  2. Name the scientists who discovered the electron and the nucleus.
  3. State the names of the three subatomic particles as well as their masses and charges.
  4. State where in the atom protons and neutrons are found.
  5. State where in the atom electrons are found.
  6. Copy and label the image of the atom. Words: electron, proton, neutron, shellLithium atom
  7. Describe in your own words what an atom looks like. Include information about the charges and masses of the subatomic particles.

Women in Science: Mary Anning, Pioneering Paleontologist

Image credit ‘Mr. Grey’ in Crispin Tickell’s book ‘Mary Anning of Lyme Regis’ (1996)

Mary Anning came from quite disadvantaged beginnings, being born into a poor English family in 1799. Out of 10 children only she and her older brother survived into adulthood. Her father was a cabinet maker by profession and a keen fossil hunter on the side. He took Mary along for his collection trips and taught her how to clean and look after the fossils which he would often sell in his shop. When her father died of tuberculosis in 1810, Mary, still a child at the time, was encouraged by her mother to help the family financially by selling her fossils.

As a child Mary received very little formal education due to the lack of money in her family. She could read, but had to teach herself geology and anatomy.

Together with her brother, Mary discovered the first Ichthyosaur fossil (the remains of a marine reptile) when she was only 12 years old. After she had uncovered the 5.2 m long skeleton, scientists initially thought it was a crocodile. They debated the find for years.

You need to remember that at this time, the idea of extinction had just recently been introduced by Georges Cuvier. In addition, Charles Darwin did not publish his theory about evolution for another 48 years. People’s views on the creation of species was still largely based on the accounts of the Bible.

In 1823, still only aged 14, Mary was the first to discover a complete skeleton of a Plesiosaur (a ”sea dragon”), another marine reptile and even more controversial find. The fossil looked so strange and unlike any living animals, that it was rumoured to be a fake. Five years later followed the discovery of Pterodactylus, the remains of the first winged dinosaur found in Britain. In addition to uncovering many skeletons, Mary pioneered the study of coprolites, which is fossilized poo.

Mary was extremely proficient in uncovering, cleaning and identifying fossils. She continued to unearth countless remains. Many were sold to male scientists who profited from her work. Nevertheless, she was never recognized for it. Mary was not even mentioned in the papers about her groundbreaking Ichthyosaur find.

Mary died of breast cancer in 1847, aged only 47. Although she was never acknowledged formally for her discoveries, she left a great legacy of scientific discoveries. There are scientists who believe that her findings have in part contributed to the theory of evolution introduced by Charles Darwin over ten years after her death.

 

 

 

 

What are zoonotic diseases and what does the destruction of rain forest have to do with it?

Image credit: David DennisFlickr: Bat in a Cave. CC BY-SA 2.0.

Ebola, HIV, rabies and the Corona virus. They all are caused by germs that can spread between animals and humans, also called zoonotic diseases.

HIV most likely originated from chimpanzees that were hunted and eaten for meat.  Similarly, Ebola is linked to the consumption of bush meat, especially bats.

The infamous Corona virus is thought to have jumped species first at a ”wet market” in Wuhan, China. Wet markets are traditional places that sell dead and live animals out in the open. These markets pose a good opportunity for a virus to jump species because hygiene standards are low and they are densely packed with people. However, the exact animal source of the Corona virus is still unknown. But bats are suspected to be involved here as well by infecting chicken, which was then consumed by humans. These winged mammals are often a source of zoonotic diseases because they live in large groups and travel far distances.

Normally, it is not that easy for a virus to jump from one species to another. When an organism gets infected a virus hijacks its cells to make copies of itself. To enter a cell, the virus has a key-like structure on its surface that will only let it into the cells of one single species. However, during the copying process mistakes are made and mutations occur in the key-like structures. With some luck for the virus one of these mutations will enable it to enter the cells of another species, for example humans. The virus has jumped species. This process is easier if hygiene standards are low and places are densely packed.

Research by scientists from the universities of Bonn and Ulm (Germany) also suggests that the destruction of ecosystems like rain forests may enable infections to jump species more easily. The researchers looked at ecosystems in Panama comparing undisturbed rain forest, smaller rain forest islands in the Panama Canal and small islands of rain forest within in an agricultural landscape.

Biodiversity is reduced in these small rain forest islands compared to intact rainforests. For example, there are fewer species of bats and rats. Therefore, individuals of the same species live closer together and are less dispersed. The results of the German research team showed that this also made it easier for different kinds of virus to spread within the populations of the remaining rats and bats giving these germs larger reservoirs. This could in turn make it easier for a virus to jump species and infect humans.

It is quite astonishing that the destruction of ecosystems could indeed influence our health by increasing the risk of zoonotic diseases like Ebola, HIV and the Corona virus.

 

How winters are disapperaring in Sweden

Photo: Artificial snow for cross country skiing in Falun’s ski stadion.

Two and a half years ago I moved to Southern England from Sweden. One thing I have really missed since relocating are the Scandinavian winters, especially being able to do sports like cross country skiing.

For this reason, my husband and I decided to go cross country skiing in Sweden over the February holidays this year. We chose to go to Falun in central Sweden. The town has a long tradition of cross country skiing, being the location of Sweden’s National Cross Country Skiing and Ski Jumping Centre as well as having hosted four Nordic Skiing World Championships in the past.

As a child, I often saw Falun’s surroundings on TV when watching international cross country skiing competitions, its forests covered by thick snow. Until recently the town was indeed a place with guaranteed snow for skiing during the winter months, but not anymore. Climate change does not care about long winter sport traditions.

When we arrived during the second half of February, temperatures were constantly above 0 degrees Celsius, peaking at 8 degrees Celsius. No need to say that there was no real snow for skiing. With many trees starting to sprout due to the high temperatures it felt more like spring than Scandinavian winter.

We were lucky that there was at least some artificial snow prepared for cross country skiing in the ski stadion. In the image above you can see me in the ski stadion in front of the ski jumping hills. The lack of snow in the image is quite obvious.

When looking at the snow depth map provided by the Swedish Meteorological and Hydrological Institute (SMHI) for the last seven days it can be seen that half of the country does not have any snow. The Southern half of Sweden as marked as ”bare ground”.

According to the Japan Times temperatures had climbed to 5 degrees above normal in Southern Sweden and 10 degrees above normal in Northern Sweden during January. The article tells us that the situation is the same in Norway, Finland and North West Russia. What I personally found most disturbing was the account of a Norwegian town that had reported 19 degrees Celsius this January.

Climate change is here to stay. Winters in Sweden and other Scandinavian countries will continue to get warmer and shorter. In many regions winters will disappear completely.

 

How climate change and a tiny beetle destroy German forests

Image: Forest in the German Harz Mountains that has been damaged by the bark beetle.

At the moment the news talk a lot about of the wildfires in the Amazon and the Arctic. But climate change and human activity also pose other dangers to forests, as can be seen in Germany.

During this summer family and friends had told me quite a bit about the extreme heat wave and drought in Germany. I had also heard through the news that German forests were suffering as a consequence.

However, none of this prepared me for what I saw when visiting my family home in the Harz Mountains in the middle of Germany.

As long as I can remember, the area around my home town has been covered in dense spruce forests. Much of my childhood was spent roaming these forests, looking for interesting animals and playing with friends.

When we approached my home by car at the end of August it was very clear, that this vast coniferous forest is sick. Like in the image above, many trees had lost their needles and large proportions of the forest had been felled leaving empty, moon-like landscapes.

You might think that the trees are only dying because they do not get enough water, but it is not as simple as that. Yes, the drought and hot temperatures limit the trees water supply. Nevertheless, the coniferous trees are still able to get enough water for their basic functions like photosynthesis. But the lack of water damages the spruce’s ability to defend against pests like the bark beetle.

The bark beetle is a tiny insect measuring about 6 mm (0.25 inch) that reproduces inside tree bark. The male and female drill into a tree to build a chamber for their eggs. After hatching the larvae bore away from the egg chamber feeding on the inner bark. This harms the part of the wood which transports water and food. In addition, the plant’s ability to form fresh bark is decreased. As a consequence, the tree will slowly die.

Like our skin the bark of a tree keeps out diseases and parasites. The normal response to a bark beetle attack is the secretion of tree sap to suffocate the beetles and their larvae. But in the event of extreme drought and heat, the trees cannot produce enough sap. Like the human immune system, the tree’s defenses do not work well under extreme stress.

The bark beetle has always been a pest in the Harz Mountains, my home area. One reason for this is that the trees are grown as a monoculture that mainly includes spruce. Deciduous trees are much more resilient towards the bark beetle and can form a natural barrier when planted in between spruces. Unfortunately, the forest is cultivated and managed by the timber industry which is only interested in the fast-growing spruce.

Despite the old monoculture problem, the current explosion of beetle infections is unprecedented and a consequence of climate change. Summers have continuously gotten hotter. During this year’s July heatwave even the – normally chillier – Harz Mountains reported temperatures above 35 degrees Celsius over several days and many new temperature records. At the same time the amount of rainfall in summer has decreased. Also, warmer temperatures allow more bark beetles to survive the winters.

The sad part of this story is that the National Park in the Harz Mountains is most severely affected. The park was founded in the early 1990s on former timber industry lands, covered with spruce monocultures. The aim was to let the land develop naturally into a mixed forest over many years. Now climate change and the bark beetle seem to be speeding up this process by destroying most of the spruce trees.

While the timber industry removes damaged wood to prevent healthy trees from getting infected, this cannot be done in a National Park where nature must be left to its own devices. As a result, the areas containing sick and dead trees are much larger in the National Park compared to the timber forests. This development could be a chance for deciduous trees to colonize the National Park faster forming a natural, mixed forest.

The future of the timber industry forest is not as clear. It is obvious that spruce monocultures will not survive the changes that global warming brings for much longer. There are now discussions in Germany to introduce foreign tree species that can cope better with heat and drought to replace the spruce. Maybe some forestry commissions will even move towards more natural mixed forests.

Looking at the dead trees and moon-like landscapes right now, I am wondering if this area will ever regain its former beauty. I cannot help but ask if my own children will ever see the vast forests of my own youth here. You do not need wildfires to destroy large amounts of forest. The trees in Germany are being destroyed by climate change and a tiny beetle.

I believe that the Harz Mountains and other German forests will eventually recover, the National Park by slowly developing into a natural, mixed forest and the timber forests possibly by introducing foreign tree species. But there is a chance that the spruce trees, that have been so iconic for German forests over centuries, could be gone.

Women in Science: Rosalind Franklin and the DNA Structure

Image credit: MRC Laboratory of Molecular BiologyFrom the personal collection of Jenifer Glynn. 1955. CC BY-SA 4.0.

One of the most important researchers involved in discovering the structure of DNA (deoxyribonucleic acid) would have celebrated their 99th birthday on July 25 this year. No – it is not James Watson or Francis Crick. It is Rosalind Franklin, a brilliant chemist, whose contribution to the discovery of DNA’s structure has gone largely unrecognized.

Rosalind Elsie Franklin was born 1920 in London. Aged only 15 she decided she wanted to be a scientist. Her father discouraged her scientific interest knowing that at the time such a career choice would be very difficult for women. Nevertheless, in 1938 Franklin enrolled at the University of Cambridge to study Chemistry.

After graduating in 1941 Franklin was awarded a research scholarship to complete a PhD. However, this work was cut short by the start of World War II. The young researcher gave up her scholarship in order to work for the British Coal Utilisation Research Association, where she investigated ways to use coal and carbon in the war effort. Fortunately, she could adopt this research into her doctoral thesis and received a PhD from the University of Cambridge in 1945.

In 1947 Franklin went to Paris, where she worked with Jacque Méring, an expert in X-ray crystallography. X-ray crystallography or X-ray diffraction is a technique that uses X-rays to determine the arrangement of atoms in a material. It is still widely used today in scientific research.

Her time in France not only taught Franklin the technique of X-ray crystallography, but also how to tackle scientific challenges. She would later need both skills to discover the structure of DNA.

So, why did people bother to figure out the structure of DNA? DNA or deoxyribonucleic acid is the genetic material inside your cells. DNA is like a blueprint or building plan for your body. It basically tells the cells of your body what to do. Almost all organisms store this building plan as DNA in their cells.

In 1951 Rosalind Franklin returned to Britain joining King’s College in London. There she started applying her knowledge about X-ray crystallography to study DNA. Franklin’s biggest contributions in the hunt for the DNA structure was finding the density of DNA and the insight that DNA forms a helix. A helix is a structure that looks like a cork screw or a wound staircase.

Franklin did not know that she was in a race with two other scientists from the University of Cambridge, James Watson and Francis Crick. Even worse was that Franklin’s colleague at King’s College Maurice Wilkins had developed a friendship with Watson and Crick. Without Franklin’s knowledge or permission Wilkins passed on her results to Watson and Crick.

Finally, Watson and Crick combined Franklin’s findings and her X-ray diffraction images of DNA with their own research. Again, this was all done with neither Franklin’s knowledge nor her permission. In April 1953, together with Wilkins, they announced that the structure of DNA was a double helix, or in other words a wound ladder. The race was over.

Soon after Franklin took a position at Birkbeck College, London, where she continued to work on coal and DNA. In addition, she started to determine the structure of viruses, which Franklin herself saw as her biggest success. Rosalind Franklin died of cancer in April 1958, aged only 37. She never knew of the contribution she had made to discover the structure of DNA.

James Watson, Francis Crick and Maurice Wilkins were awarded the Nobel prize in Medicine for the discovery of the structure of DNA in 1962.

When discussing why Franklin did not receive the Nobel prize, the first argument is always that she died it was awarded in 1962. It is true that the Nobel prize is only awarded to people who are alive. However, in my opinion it is very unlikely that Franklin would have received the prize even if she had been alive in 1962.

There are two reasons for this. The first is that Watson, Crick and Wilkins never mentioned Franklin’s results in their publications despite having used them for their own work. In fact, Franklin never knew herself how much she had contributed to their model.

The second is that at the time women were just not well regarded in Science. When Franklin died in 1962 only three women had ever won the Nobel prize, Marie Curie, Irene Joliot-Curie and Gerty Cori. In addition, she had to battle the sexism in Science in her everyday life by protesting her lower pay and lack of promotion compared to her male colleagues.

Women in Science: Valentina Tereshkova, First Woman in Space

Image Credit: NASA

Most people know that 1961 Yuri Gargarin was the first man in space. Most people also know that 1969 Neil Armstrong was the first man on the moon. However, few people know when the first woman went to space.

The first woman in space was Valentina Tereshkova in 1963 – only two years after Gargarin’s tour. This is an incredibly short time considering how long it took the Americans to send their first woman to space. Sally Ride launched with the space shuttle Challenger in June 1983 – 22 years after the first American, Alan Shepard, went to space.

Having left education early, Valentina worked at a textile factory in a small village in Russia. Many might consider this early career unlikely for a future cosmonaut. However, Valentina was a passionate parachutist. This hobby later qualified her to join the cosmonaut training program. Recruitng parachutists to the space program was not uncommon at the time because early cosmonauts and astronauts had to parachute out of their space craft when landing back on Earth.

After winning the race of putting the first man into space, Soviet leadership was determined to also win the race of launching the first woman. Therefore, they sent out incognito spotters to parachuting clubs to find women suited for the cosmonaut training program.

After further tests, Valentina was selected for training along with four other women. Three of them had university degrees in technology and engineering. So, why was Valentina chosen before them? Soviet leader Nikita Khrushchev got the final pick and he chose Valentina mainly because she was the best fit for party propaganda. Her father had died as a soldier during World War II and she was clearly of the working class.

Valentina launched into space aboard Vostok 6 on 16 June 1963 and orbited the Earth 48 times. After three days she landed in the Altay region in Kazakhstan.

After her return, Valentina was greatly celebrated by the Soviet leadership and became an important propaganda figure. However, she never flew in space again.

Author’s Comment

Despite being chosen as the first woman in space partly for propaganda reasons, I believe, we can learn something important from Valentina Tereshkova’s career.

Valentina left school early and worked in a textile factory, but managed to join the astronaut program. She pulled off a major career change. This means it is never too late to learn something new, change your career or apply for that training program or course you always wanted to do.

Teenagers today are often told that they need to figure out exactly what they want to do with their lives by the ages of 15 or 16. After that that’s it. You are stuck with your choice. Valentina’s story shows that this is not true. You can start out as a textile worker and end up going to space.