Tuesday, August 31, 2010

The case of the organic salt

I live in a city with a lot of organic food shops which gives me a fabulous amount of food choices that I didn't have when I lived in other places. But, I have to admit some things for sale at these shops don't make a lot of sense – like organic apples from New Zealand (a hemisphere away from my home) for sale at the same time I can get them fresh and ripe from a local orchard.

Because we were curious if we would actually find it, my significant other and I decided to look for organic salt. Our theory was that organic salt would be found if we looked for it. Remember, that by definition salt is inorganic because it was never living and is not made up of any carbon – it's just sodium and chloride.

We checked two shops and didn't find our salt. But, at the third shop we found it – a package labeled 'organic salt'. The only ingredient was salt. I didn't buy any as I can make due with the plain old inorganic stuff (and I'm a little confused about what would make salt organic). When I got home I did google search for 'organic salt'. Pages of products come up ranging from foods to bath products. I can't stop myself from thinking manufactures, including the organic shop since the organic salt we found there was a shop brand, are just jumping on the organic band wagon and using it as a buzz word.

Monday, August 30, 2010

Flow over bumps

As Fluid flows over a bump surface disturbances, such as waves, develop potentially extending both up and downstream. The form these disturbances take depends on fluid velocity and fluid depth which can be combined together in the Froude (F) number. The Froude number equals the fluid velocity over the square root of gravity times fluid depth. Because it has no dimensions, the Froude number allows flow in dramatically different circumstances to be compared, for example, atmospheric flow over a mountain range could be compared to tap water flow from your kitchen sink.

Naval architecture provided the original application for the Froude number. Here the hull length of a ship is used instead of fluid depth. It's important because, the Froude number relates to the ship's drag or resistance to moving through the water. This number is named after William Froude (1810-1879) who experimented on ship's hulls in his large fluid tank. William developed towing tank techniques in his efforts to model frictional drag on ships. However, he didn't discover the dynamical relationship between the fluid velocity and hull length. It was Ferdinand Reech (1805-1880) who first described this relationship and used it for testing ships and propellers around 1852. It's likely that this relationship's roots reside with even earlier French mathematicians.

So what does the Froude number tell us? When F is smaller than one, flow over the bump is 'subcritical'. Waves on the surface can travel upstream, meaning that downstream conditions affect the flow upstream. For example, when a pebble is tossed into the water of a flowing stream, the resulting ripples propagate both upstream and downstream. When F is larger than 1, flow is 'supercritical'. In this case, no surface disturbance can travel upstream. The ripples created by a pebble tossed in downstream cannot overcome the speed of the water. The flow upstream is not changed. When F is equal to one the flow is 'critical'. This is the point of transition from subcritical to supercritical effects.

Now, back to flow over a bump. As subcritical water is pushed over the bump, squeezing takes place because the water is now shallower and the same amount of water is flowing through. This forces the water to speed up over the bump and transition to supercritical. This faster water crosses over to the other side of the bump, where it's again deeper and slower moving. When the fast flowing water reaches the slower water it abruptly slows and waves form. Since the water is moving too quickly to allow waves to propagate upstream, (because it is supercritical) these waves build up, forming a sudden water level increase that can be standing still in the flowing water. This is called a hydraulic jump, a non-linear effect and can be observed in a kitchen sink or in water passing over a weir. Mathematically, a hydraulic jump is a discontinuity, however in the real world viscosity makes it a region of rapid change instead.

The greater the Froude number is, the more pronounced the jump will be. For initial flow speeds slightly above the critical speed, the transition appears as an undulating wave. As flow speed increases, the Froude number also increases and the transition becomes stronger eventually developing a more abrupt shape. When the speed is high enough, the transition front will break and curl back upon itself. At this point, the jump may contain violent turbulence, eddying, air entrainment, and surface waves. Turbulence removes the extra energy, allowing the flow to transition from supercritical back to subcritical.

Tuesday, August 24, 2010

Playing With Food

I was searching the internet for information on non-Newtonian fluids (which I'll write about in detail later) and came across a wealth of articles regarding the study of food textures. There is even a journal devoted to these texture studies. A quick look at the authors showed most worked for major food companies and the focus was on processed food (which I avoid or process myself) – nevertheless, I found myself drawn into their studies.

Some studies take the same approach as oceanography (my field) by considering a unit volume and the stresses that act on it. I'm delighted to know this has been applied to different gummy formulas, along with studying their attractive transparent appearance and textural attributes – for if I could eat one candy item until the end of time it would be gummy candies.

I also found a study out of India that looked at replacing a percentage of wheat flour in bread with a mixture of ground-up soya beans, oats, fenugreek seeds, flax seeds, and sesame seeds. The resulting loaves of bread were examined under a scanning electron microscope along with being tasted. Replacing 15% of the flour with this mixture resulted in bread that was just right. In another Indian study, the addition of ground flax seed to muffins was tested by a panel of six. This panel judged the muffins on crust colour, crumb colour, grain, texture, taste and over-all quality. Food has become complex!

I assume these studies happen because the processed food industry is big business, and I'm pleased to read that nutrition is included. One article from the Journal of Food Engineering declared 'not all foods are processed beginning with pure components; in fact most food products have their origin in the animal and vegetable kingdom.' I have to admit that the idea of foods (other than salt) that don't come from the animal and vegetable kingdom (assuming they are including fungi – mushrooms are tasty) worry me a lot. I wonder if bread analyzed under a scanning electron microscope really is any better that the bread I bake in my kitchen.

Tuesday, August 17, 2010

Waves in the ocean - or why I don't like helicopters

It is a confused pattern that the waves make in the open sea – a mixture of countless different wave trains, intermingling, overtaking, passing, or sometimes engulfing one another; each group differing from the others in the place and manor of its origin, in its speed, its direction of movement; some doomed never to reach any shore, others destined to roll across half an ocean before they dissolve in thunder on a distant beach.

– Rachel Carson, "The Sea Around Us"

Years ago I took a ride in a helicopter that took off from a ship's deck. I was able (with a tether) to sit with my feet dangling out the door and nothing obstructing my view to the ocean surface. I watched the undulating waves below. At the ocean surface there was little wind that day, so the waves weren't breaking. I thought we were a short distance from the surface, maybe less than 50 m, until a seagull flew beneath us. The bird was a tiny white speck, so we had to be several hundred metres up. The fact that I couldn't tell how high we were is interesting and many other observers have noticed the same thing.

The surface of the open ocean is complex, like the quote above describes. Waves of all sizes occur at the same time. Ocean surface waves are mostly created by the wind; once they are created they can travel a great distance and interact with waves created else-where. The size and speed, thus energy, of a wave is related to the length of sea the wind blows over, called fetch, and the strength of the wind. A large storm lasting several days can create energetic waves. Once these energetic waves move out of the storm area they are called swell. Now the more energetic waves move faster than less-energetic ones resulting in a sorting of waves. Water is great at transmitting waves, meaning these energetic waves can reach the opposite side of an ocean basin where they potentially create great fun for surfers.

Without a point of reference, like a shoreline or a seabird, there is no way to tell what size of motions you are looking at once you reach a certain distance above the water. Obviously, you could tell how far away you were if you were getting sprayed by the water – but by then you are very close. A skydiver over the open ocean wouldn't be able to tell how high they were without an altimeter. If the altimeter failed it could be a potentially dangerous situation.

On the next flight of that helicopter there was an in flight emergency that resulted in a near water landing. Passengers on helicopter that land (or crash) on the water, typically don't make it out. Helicopters usually flip when they hit the water and dealing with getting out can be very disorientating without training. Since there was a passenger on board, the pilots attempted a deck landing (they didn't want to be responsible for a dead passenger). Those of us on the ship were all in our firefighting gear just waiting for a crash – so it was a very serious situation. Although everyone was okay, at that point I decided never to ride in a helicopter just for fun again (even though I am up in them quite often for work).

Wednesday, August 11, 2010

Dreaming - no plot spoilers here

I went and saw 'Inception' on the weekend and really enjoyed the layers and complexity to their dream worlds, although they could have gone further with the weirdness of dreams. What really stuck out for me was the use of an old-fashioned elevator in the main character's own dream. This elevator took him between memories, one floor a day at the beach, another one a hotel room. It wasn't implicitly stated, but I got the impression that the lower the elevator went the more intense emotionally the memory was.

An elevator as a means to move between dream worlds resonates with me. I've often had my own versions of an elevator in my dreams, the same type of old-fashioned one with push button controls and mesh doors one has to pull shut before the elevator will move. Even the yellowish, dim, flickering lighting was the same. I guess my use of an elevator isn't unique, so I wonder how often an elevator of some form pops up in people's dreams? (I also wonder if its use will increase for people who have watched the movie.)

Thinking about dream worlds connected by elevators has lead me to thinking about dreams themselves. Like many people, I've always had full colour, vivid and bizarre dreams. Why do we dream? The answer is that we really don't know, but there are many theories. For me, I like the idea that dreams are a mechanism to sort and file random thoughts, fleeting impressions and half-formed emotions. This theory was first put forward in 1886 by a physician from Hamburg named Robert (a quick internet search didn't bring up any detailed info on him). Later this theory was built on by others including Freud.

I don't think there is deep meaning hiding in my dreams from somewhere beyond my own waking world. I've had ideas come forward in my dreams, but they were on things I was already thinking about. For example, I was looking for a SCUBA octopus (regulator, buoyancy compensator regulator, instrument panel etc all connected together with air hoses). One had gone missing after a group dive. We looked all over for it and spent a long time thinking about where it could be. That night, I dreamed it was hanging up on my dive partner's bedroom door under his bathrobe. The next day we looked and there it was. I didn't get any new information in that dream, although it would be easy to interpret it that way if I was so inclined. Instead, my mind just sorted through the information I already had.

Another point I've been pondering: are dreams continuous? By that I mean, are dreams like movies with a continuous flow from beginning to end? I don't think so or at least I don't think mine are. What I suspect is my mind takes the disjointed ideas and emotions and forces them together into the story I remember. Our vision functions like this – our eyes pick up small chunks of the world around around us and our mind puts them all together into a continuous environment. So why can't our mind take the pieces of a dream and put them together?

Tuesday, August 10, 2010

What do blue jays and the sky have in common?

I've only ever caught a glimpse of a blue jay out of the corner of my eye as a flash of blue. I have, however, had plenty of opportunity to watch Steller's jays. Instead of the blue and white of a blue jay, a Steller's jay is black and blue and every bit as pretty. The blue made in these jays' feathers uses the same principle as the blue sky.

In 1810 Goethe explained blue skies as follows: “If the darkness of infinite space is seen through atmospheric vapours illuminated by the day-light the blue colour appears.” So, the colour comes from some mechanism within the atmosphere during the light of day. (I really like the phrase 'darkness of infinite space.')

Fast forward a few years to John William Strutt (1842-1919), also known as Lord Rayleigh, who was the first to describe the actual mechanism that makes the sky appear blue. He also studied the dynamics of seabird flight, so I'm assuming he often looked off into the sky. Anyway, the effect is called Rayleigh Scattering.

Absolutely tiny particles, like water drops and dust, can be so small they reach a point (about a tenth of the wavelength of light) where light will bend around the particle. The bent light is then scattered differently than it would be for larger particles, in that shorter wavelengths (like blue) are more strongly scattered than longer ones (like red) so we end up seeing the blue. So why not violet, as its wavelength is shorter than blue? It turns out our eyes are just more sensitive to the blue.

Blue feathered birds like blue jays also use Raleigh scattering to get their blueness. Within the structure of their feathers are transparent cells full of tiny particles and pigments. The pigments absorb the longer wavelength colours while the particles scatter efficiently scatter the blue light. To out eyes, these birds look blue.

If you find a blue jay's feather, take care with it because this structure is fragile. If it got crushed the blue colouring would vanish.

Update 26 November 2010 - I didn't quite get this one right, check out here for the start of a better explanation.

Sunday, August 8, 2010

Looking closer to home

Way back in grade eight, each of us in my science class was to make a poster depicting interesting aspects of a planet or moon in the solar system (this was before Pluto was demoted from full planet status and the category of dwarf planets was added). The project was right up my alley, so I spent a fair amount of time thinking about which planet I should choose. In the end I chose earth, what could be more interesting than our home?

Other planets have their fascinating aspects: how exotic are clouds of sulfuric acid? Or the possibility of a planetary ocean beneath a thick layer of permanent ice? Fascinating for sure, but everywhere I look on this world we live on I see something spectacular (albeit not aways on a huge scale) and I can often interact with it directly.

I have witnessed sea ice extending to the horizon in every direction in the arctic, the folded rock that juts up as the Rocky Mountains and, a volcano that spewed into the sky glowing boulders the size of cars that broke apart as they tumbled down the mountain side in Costa Rica. Often, little things are just as captivating. Such as changing patterns in the surface of a stream as the water makes it way around rocks or the hum of bees harvesting the pollen from my bachelor buttons. I could go on. There is no shortage of fascinating things that I've read about, seen in pictures or don't even know about yet. I don't there are fascinating things at all scales on the other planets – and if they are looking for volunteers to go look, sign me up! Until then, I'll stick to the world around me.

The day our posters went up, I realized I was the only one who choose earth. Unfortunately, my eight grade science teacher didn't think Earth was exotic enough, so I did poorly on the assignment. I have to admit he didn't influence me much and don't even remember his name – the only other project that we did that I can remember was dissecting a sheep's eye. I just continued to go outside and explore the world around me.

The bee in the photo is from my backyard

Tuesday, August 3, 2010


Way back when I took first year chemistry I found the labs to be great fun. In one lab we made our own nylon. Now, actually wearing nylons is something I despise, one step down the slippery slope to high-heels (I'm 5'10”, I don't need to be taller) and caking my face with excessive make-up, not to mention an exponential requirement for more hairspray. It's probably obvious I'm not a girly-girl, nor ever plan on becoming one (if you are a girly-girl, go ahead and be girly, I'm not judging, it's just not my thing). But, making nylon intrigues me as I'm always interested in how things are made.

The invention of Nylon is credited to Wallace Carothers in 1935 at the DuPont Experimental Station. In 1930, Carothers with the folks at DuPont had their first success with what would be eventually called neoprene – the first synthetic rubber. Carothers and his team went on to tackle the creation what would become nylon. Unfortunately, Carothers tended to bouts of depression and alcoholism, and his actual contribution to the development of nylon probably wasn't significant. Instead his coworkers did the work and credited him. In 1937, Carothers committed suicide.

Nylon was the first synthetic fiber, in a 22 September 1938 New York Times article nylon was touted to be 'stronger than steel, fine as a spider's web, more elastic than any of the common natural fibers'. Once it was announced nylon could be knitted in to stockings that were better than silk people got excited. Ironically, the first commercial application turned out to be a nylon-bristled toothbrush. Nylon stockings were said to be indestructible (I've worn nylons enough times to know that isn't true). Today nylon fibers are the second most used synthetic fiber and can be found in all sorts of things like: fabrics, carpets, musical instrument strings and ropes. The down side to nylon is that in a fire it breaks down into nasty stuff like hazardous smoke and toxic fumes. Most nylon ends slowly decaying in landfill as recycling for it isn't widely implemented.

According to Wikipedia to make nylon, molecules with an acid group on each end are reacted with molecules containing an amine group on each end. They react and form long polymer chains – and that's is what nylon is, just a trade name for a synthetic polymers.

On to how we made nylon fiber in my first year lab. I poured one liquid very carefully over a the back of a metal spoon into a glass jug so it sat on top of another liquid without excess mixing. I had forgotten what the chemicals were, but a quick internet search gave me hexanedioxyl dichloride and diaminohexane. After a minute or so a layer formed between the two chemicals. With some tongs, I pulled out the interface, which had changed to nylon. As I pulled the two liquids would form new nylon when ever they came in contact with each other and I ended up with a long string of nylon. So, from the boundary between two liquids came a length of nylon thread.

Sunday, August 1, 2010

Bumps in the Road

I just got back from a rather long road trip. We drove from my island in the Pacific half-way across North America to attend a wedding. The trip there we did in two very very long days (we took a more civilized three days to drive back with a day off in the middle). Once we hit the prairies on the second day there was nothing but flat farm lands as far as I could see and I was bored of being in a car. So I set my mind to pondering my surroundings which mostly consisted of sky, prairie and the road we were on.

We were barreling down a major highway that was also a thoroughfare for convoys of tractor-trailers. Since these trucks haul heavy loads, when they brake all that momentum from their load goes into the highway surface, slightly pushing down the highway beneath the tires and creating a bump in front like a really hard version of a cushion. If one was to push down on the cushion with your hand, the cushion would depress beneath the hand and raise up around it. On the highway, this effect builds up over time creating dips and bumps, and since the trucks don't break all that the same place, a wash board effect can develop along the highway surface. Cars contribute to the same effect, but since they weigh a fractions of a fully loaded tractor-trailer their effect is minimal. I've done a lot of long distance highway driving and experienced this effect of driving on a what feels like a wash board many times.

What we noticed this time was dark splotches on the highway just after each bump – the larger the bump the darker and larger the splotch. I'm guessing the dark splotches are oil, the cumulation of little drips shaken loose by the bump from thousands of passing cars. In the July 2010 Scientific American, I found the statistic that the average annual spillage of oil from natural seams and human activities such as transportation is 380 million gallons globally – I wonder how much of that comes from oil drips released by bumps in the road?