# Helix @ CSIRO

## Arrow maze

When making an arrow maze, start by drawing a path from the ‘In’ box to the ‘Out’ box.

### You will need

• Paper
• Overhead projector sheet or tracing paper
• Permanent marker
• Pens or textas
• A copy of the arrow maze [pdf, 7kB]

### Solving an arrow maze

Although it might not look like it, this puzzle is a type of maze. The rules are quite simple:

1. Start at the box labelled ‘In’.
2. There are arrows in the box. Follow one of them to the next box.

Overlay a transparency and then draw arrows along the path.

3. This box also has arrows. Pick one and follow it. Keep following arrows until you get to the box labelled ‘Out’.
4. This maze has a loop from which you cannot escape – if you end up in the loop, you’ll have to start again!

### Making an arrow maze

1. On a sheet of paper, draw a 5 x 5 grid of boxes. (Or you can make it even bigger!)  Label one box ‘In’ and one box ‘Out’.
2. Draw a path travelling from box to box, starting at ‘In’ and ending at ‘Out’. Don’t go to all the boxes and never visit the same box more than once. This path will be the solution to your maze.

4. Trace the outlines of the boxes onto your overhead projector sheet and label the ‘In’ and ‘Out’ boxes.
5. Following the path, draw an arrow in each box that leads to the next box.
6. Put extra arrows in some of the boxes to trick people into going the wrong way. Make sure you don’t make any shortcuts!
7. Put arrows in any empty boxes. Again, be careful not to make any shortcuts.
8. Get a fresh sheet of paper and copy your maze from the overhead projector sheet onto the paper. Look at it carefully to make sure it’s possible to get from the ‘In’ to the ‘Out’.
9. Give your maze to your friends and family members to solve! You might want to photocopy it first, so they can draw on it.

### What’s happening?

This arrow maze is similar to a ‘normal’ maze – there is a start point and you follow paths to try to find the exit. If you trace all the paths you can follow, you’ll end up with a ‘map’ of the maze. This map will look similar to a normal maze.

There’s a big difference between arrow mazes and normal mazes. An arrow maze is directed – there are some paths that you can only follow in one direction. With a normal maze, you can go down any path in either direction.

### Applications

Following paths to make connections has a range of important applications in science and everyday life. These networks of information can be used for traffic planning in cities, or analysing food webs in ecosystems. In many cases, these networks need directed links – paths that can be followed one way and not the other. For example, in traffic planning there may be one way streets. In food webs, an animal may eat a plant, but the plant can’t eat the animal!

## Make-a-mummy update: Week 1

After letting it sit for three days, I checked out my chicken mummy. The mixture of salt and bicarb looked like it had absorbed a fair bit of water, and I detected a faint whiff of something rotten. Yes, it was coming along nicely!

Not wanting to gross out my co-workers, I took the bag home. It was raining outside, so I decided the laundry was the best place to open the bag. I put the tray in the bottom of the sink, and opened the bag. I poured the contents into the tray. The smell was revolting – even worse than I expected.

After the smell, the next thing I noticed was the colour of the chicken. The skin was no longer a pale pink – it had turned much darker, while the flesh of the chicken had turned yellow. The skin was dry and leathery.

Observations: the chicken smelled awful, its colour had changed and the skin felt like leather.

Trying not to be sick, I cleared away some of the drying mixture that had crusted on. The mixture of salt and bicarb was doing its job. It was clumping together and felt moist, indicating that it was absorbing the water from the chicken. I removed the sock from the cavity of the carcass. It was actually damp – that’s how much water it had absorbed. I filled a new old sock with drying mixture and put this in the cavity.

I got a new bag, poured some fresh drying mixture into it, added the chicken and sealed it. I now had four kilograms of used drying mixture. I realised that if I kept using a fresh mix every time, I could quickly cause a salt and bicarb shortage. So, I came up with an idea: I could dry out the mixture and reuse it next time.

I turned the oven on to 100°C and put the tray in to dry out the mixture. My kitchen started to smell like it had rotten chicken stew boiling away. I tried turning up the heat to 250°C. The smell went away. I removed the tray after leaving it in the oven for an hour or so. The lumps had hardened, so I broke them up with a pestle, and stirred it around a bit. I put it back in the oven for another half an hour. When I removed the tray this time, I had a dry mixture again. Hopefully it will prove to be useful in a few days time!

My boss was a bit worried about people getting sick if they tried this activity. So I emailed Dr Kari Gobius from CSIRO Food and Nutritional Sciences. He said the highest risk bacterial hazards would be Salmonella, Campylobacter and E. coli. However he also offered these words of encouragement, “You have a pretty high likelihood of success with this approach because you’re really driving the ‘drying out process’ and that’s exactly what the bacteria don’t like. Bacteria love water and they’re not happy without it.”

Finally, Kari advised to keep the drying mixture away from pets, to wear gloves, and to wash your hands and any utensils thoroughly after use.

## Double Helix – back to basics

Game on! Get hands-on learning about genetics with cards like this.

Two centuries ago, nobody knew much about what made a single fertilised cell grow into a human. Or – for that matter – a dog, a sea urchin, a worm or a whale. The problem was nobody could imagine how a microscopic bag of chemicals could possibly split in half again and again, yet still have enough information to make all the different organs and tissues in the body.

Since the invention of the microscope, scientists have known many cells contain a round, dark nucleus. In the late 19th century, a Swiss physician managed to extract specific chemicals from the nucleus that he called nuclein.

Bit by bit, over the following decades, chemists worked out what was in this goopy material. There were hints that these chemicals could hold the key to what turns a simple cell into a complex organism. Finding convincing evidence took a long time.

The chemicals are acids, so they became known as nucleic acids. Then scientists found different types of chemicals that were described as bases – including adenine, thymine, guanine and cytosine. It was later discovered that they were all linked in chains.

In the early 1940s, a physicist by the name of Erwin Schrödinger gave lectures on life. He imagined a chemical with repeating units varied enough to code information. The talks were inspirational.

The pieces were coming together. Deoxyribonucleic acid (DNA) is passed from one generation to the next, carrying information telling the cell how to grow and change.

In 1953, two names became famously linked with DNA – James Watson and Francis Crick. Using an X-ray image prepared by a physicist named Rosalind Franklin, they calculated the structure of the nucleic acid. The result was the familiar twisting ladder of the double helix.

The story doesn’t end there. Even today, we’re still learning how DNA molecules change shape, combine with other chemicals and transform our cells.

Learning about DNA can seem rather daunting. To make it a little easier, we’ve developed a game. The goal is simple: competing against a partner, draw base cards from a pile, and arrange them according to a sequence. To make things a little more challenging, there are action cards that could help you, or help your competitor.

To play the Double Helix card game, download the cards and the instructions and print them out. If you don’t like the rules, don’t worry – the game is simple enough, you can change them to make up your own game. Feel free to share your own rules in the comments!

Maybe with some practise, one day you’ll make your own DNA discovery.

## The different faces of phosphorus

Phosphorus is used to set matches alight.
Image: Sebastian Ritter/Wikimedia Commons/CC-BY-SA-2.5

Strike a match. It lights thanks to phosphorus. This element doesn’t just have fiery applications – it’s important for life itself.

Phosphorus comes in a number of different forms, called allotropes. The two main allotropes get their names from their colours: white phosphorus and red phosphorus. Both allotropes are reactive. White phosphorus is so reactive that it can spontaneously burst into flames when exposed to oxygen. The red phosphorus used in matches is slightly more stable.

Phosphorus is so reactive that, in nature, it is only found in combination with other elements. A common combination is for one phosphorus atom to combine with four oxygen atoms to form a phosphate ion.

A number of important biological compounds contain phosphates. DNA, which holds an organism’s genetic information, contains phosphates. Adenosine triphosphate is used by cells to produce energy. In humans, phosphorus is also needed to build strong teeth and bones.

Organisms need phosphorus to survive, but too much can be a problem. Fertilisers used in agriculture often contain phosphorus compounds, which help plants grow. When these compounds find their way into rivers, streams and lakes they can also help algal blooms to grow and may damage aquatic ecosystems and lower water quality.

Run-off from agriculture as well as wastewater from homes and industry can all increase phosphorus levels in waterways. As the concentrations of this chemical are often low, it makes it difficult to remove phosphorus from wastewater before it’s released into the environment.

A team from CSIRO has come up with a new way to remove phosphorus from wastewater, called enhanced biological phosphorus removal and recovery (EBPR-r). This method uses bacteria to remove phosphorus from wastewater. While using bacteria to remove phosphorus from wastewater is not a new idea, CSIRO’s method also allows the phosphorus to be recovered. The phosphorus can then be reused to make things like fertilisers or matches.

Matches, DNA, bones, fertiliser and pollution – phosphorus is an element with many different aspects. Hopefully research such as this allows phosphorus to keep sustaining life, without overdoing it!

CSIRO: New research shows phosphorus recovery from wastewater viable

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## Make-a-mummy

Once again I left it to the last minute to get my mum a Mother’s Day present. To avoid this last minute rush next time, I’m going to start working on next’s years present, this year. If you’re in the same boat, why not follow my lead and make a mummy for Mother’s Day?

I’ve decided to mummify a chicken, although theoretically you could use any animal. Just make sure it’s dead. Really dead. Thankfully the chooks you get from the supermarket are sufficiently dead for this activity.

You will also need a big bowl, spoon, bicarb soda, salt, some paper towels, an old sock and a large zip-lock bag. Plus, if you do try this at home, it might be a good idea to get permission from anyone you live with. You want to make sure they’re ok with you doing a long, messy and possibly smelly experiment on a dead animal before you begin.

Here’s the stuff that you will need.

I recommend that you do this activity somewhere that isn’t a kitchen. It uses a raw chicken, there’s a lot of chicken juice involved and you don’t want that to contaminate food that people are going to eat. I also recommend that you use a tray to help contain the inevitable mess. And of course, once you’re done, remember to wash your hands thoroughly.

Start by washing the chicken and patting it dry with the paper towels. Mummification works by removing moisture, so the less moisture you have to start with, the better. Also remember to dry the inside cavity of the chicken. Usually the guts have been removed from a store-bought chook. If you’re lucky, some guts might remain. Feel free to mummify these as well.

I found this in my chicken. I don’t know what it is…

The Ancient Egyptians used natron to dry out their mummies. Natron is a naturally occurring mixture of sodium carbonate decahydrate (meaning that for every unit of sodium carbonate, there are 10 molecules of water) and sodium bicarbonate (bicarb soda). If you have access to natron go ahead and use it. I decided to go with a mixture of bicarb soda and ordinary cooking salt. Please note, you will need substantial quantities of both. If you are not prepared to get strange looks from the check-out chap at the supermarket when you buy a chicken and four kilos each of bicarb soda and salt, this activity may not be for you. I mixed together equal parts of salt and bicarb (a kilo of each) in a big bowl.

Mix together equal parts of bicarb soda and salt in a big bowl.

Then, I spooned some of the mixture into the sock and tied the end. This is to stick in the cavity of the chicken. I expect that I will need to change the drying mixture a few times as it absorbs water from the chicken, and I didn’t want a layer of gunky, crusty salt forming on the inside of the chook. This way I can just yank the sock out, change the mixture, and stick it back in again.

Put some of the drying mixture into a sock then stick it in the cavity.

Next, I poured some of the drying mixture into a zip-lock bag, then added the chicken. I poured the drying mixture around the chicken, shaking and squeezing the bag to make sure the mixture covered the whole bird. I found that two kilos of drying mixture isn’t enough, and I made up another two kilos. This proved to be enough.

Make sure you cover the whole bird in the drying mixture.

Once the whole chicken was surrounded by the drying mixture, I sealed the bag. I noticed that the bag had a small split in it. Rather than going through all the hassle of transferring everything to another bag, I just gaffer taped the tear.

Think of it as a combined ancient history and science lesson. In pillow form.

Now the waiting begins. I think it will take at least a month, if not longer. I expect to replace the drying mixture a few times, as it absorbs the moisture from the chicken. I will leave the bag in a dry, warm place away from other food. Hopefully it won’t smell. Much.

Every week I will post an update on the desiccation situation. If you do this activity yourself, I’d love to hear how you go! Hopefully at the end I will have next year’s Mother’s Day present sorted.

## It’s almost Mother’s Day, mummy!

Looking for a mummy this Mother’s Day? Try this activity from Science by Email.

#### You will need

• Apple

• Table salt
• Bicarb soda
• Vegetable peeler
• Teaspoon
• Plastic container or bowl that fits an apple
• Clear nail varnish or PVA glue (optional)

#### What to do

1. Peel the apple. Young scientists should ask an adult for help.

2. Using the teaspoon, carve out the features of your mummy’s head in the apple. (You could make it resemble your mum for Mother’s Day!)
3. Mix 1 part bicarb soda to 5 parts salt so you have enough to completely bury your carved apple. Now totally immerse your apple head in salt and bicarb!This is easiest if you pour some of the salt and bicarb mix into the container, place your head on top and then pour in the rest around the head.
5. You can then remove the apple head from its salty tomb. You should have a wonderfully dry, wrinkled apple mummy skull.

The salt around the apple is an example of a desiccant – it absorbs the moisture in its surroundings, in this case the apple.

6. If you are feeling macabre you can decorate it with button eyes and some human hair clippings.
7. You can also varnish your mummy head or coat it with PVA glue which will help it last for a long time. Apply the varnish in a well ventilated area.

#### What’s happening?

The salt around the apple is an example of a desiccant – it absorbs the moisture in its surroundings, in this case the apple.

Bacteria and mould thrive in moist environments, and drying out the apple prevents bacteria from causing the apple to rot.

Adding a coat of varnish helps prevent any moisture from getting inside the apple, and you can keep your shrunken head for archeologists to find in the future.

### Applications

Salt was one of the ingredients that ancient Egyptians used to make mummies. To mummify a body, Egyptians would remove the brain and all the internal organs after a person had died.

A mixture of natural salts called natron was then stuffed inside and around the body. Natron salts were native to the area, and not unlike today’s bicarb soda.

After days of drying with the desiccant natron, the body was wrapped up with linen soaked in resin. The resin hardened and acted in the same way as nail varnish by stopping moisture getting inside.

Other easily available desiccants are silica gel packets (the ones labelled ‘do not eat’) and uncooked rice. Why not try the shrunken head experiment using other desiccants to see which is the most effective?

We get really serious about mummies tomorrow on Mother’s Day. Stay tuned to find out how to mummify a chicken!

## Robotic futures

Starbug, one of CSIRO’s Autonomous Underwater Vehicles, has been used to monitor the Great Barrier Reef.
Image: CSIRO

Robots have been a popular part of science fiction for years. While robots that can think and feel like humans are still just a fantasy, robotic systems are already having an impact on our lives.

CSIRO runs one of the largest robotics research centres in the world, the Autonomous Systems Laboratory. Instead of trying to develop robots to completely replace humans, many of the projects focus on developing technology to assist humans.

One advantage robots have over humans is that they can go places dangerous or difficult for humans to get to, such as the bottom of the ocean. CSIRO’s Autonomous Underwater Vehicles (AUVs) have been used to monitor marine environments such as the Great Barrier Reef. Unlike human divers, AUVs don’t require oxygen, so they can stay underwater much longer.

Robotic systems also have applications on land and in the skies. CSIRO is a partner in Project ResQu, which developed a type of unmanned helicopter. On land, robotic systems are used in a number of industries. For example, robotic systems can be used to remotely control mining equipment, removing human operators from harsh and sometimes hazardous conditions. A bit less extreme is CSIRO’s partnership with the National Museum using robots to take remote visitors, such as rural students, on a tour of the museum.

Given the often extreme conditions robotic systems are exposed to, future research efforts will include ways to improve the durability of robotic systems. Making robotic systems ‘smarter’ and easier to use are other areas for future development.

Humans still have a number of advantages over robotic systems. We might not have a robot which can solve all our problems right now but maybe we will in the not too distant future.