Platinum and power

One of the classes I took in university was on electrochemistry and fuel cells. It was very interesting, but was also a reality check on the hype of hydrogen fuel cells vs. the reality. One item in particular that stood out for me was that the catalyst required for efficient, low temperature hydrogen fuel cell operation was platinum. While platinum isn't the most expensive metal out there, gold having passed it in price not too long ago, it's way up there. As I recall, the raw platinum required to make a fuel cell cost a significant fraction of the cost of a normal car, and that was before they processed it into a useful catalyst. Since then, they've improved the structure here and there and reduced the amount of platinum required bit by bit, but it's still a lot.

Not long ago, however, some researchers in Finland figured out a way to reduce the amount of platinum by more than half.

Rusty mittens

Just for fun, and because it's winter, I thought I'd look at mitten heaters, specifically the non-reusable type that comes with a warning not to take the plastic off until you're ready to use them. You've probably seen them sold with outdoor recreation stuff, such as camping gear. They're little cloth pockets with a powder inside, and you can stuff them inside your shoes or mittens to help keep warm.

There are a few ingredients in that powder, but only one produces heat. I think the others moderate the speed of the reaction so it lasts about a half hour, instead of getting a lot hotter and only lasting a few minutes.

The source of heat is a multi-step, electrochemical reaction: rust.

Fake snowflakes

You know how they say no two snowflakes are alike?

It turns out that they're so sensitive to the conditions they form in, and are also fragile in a turbulent area, that the odds of two snowflakes growing in precisely the same way and having the exact same collisions breaking pieces off as they go are pretty small.

There are, however, a few main shapes of snowflakes that all snowflakes follow.

Science fiction fans, rejoice!

All I can really say about this is, WOW.

NASA's Kepler team has found loads of planet candidates to date (about 2300) by measuring variations in brightness in the star as the planet orbits. They've confirmed a bunch of them as well, so we know there are other planets out there. And just in case you think 2300 is a low number considering how many stars are in the sky, keep in mind that the Kepler telescope has been staring at a patch of sky about the size of your outstretched hand the entire time. I don't know about you, but I can't even see 2300 stars in that kind of an area, and the Kepler telescope has found that many planet candidates.

Now they've found one in its star's habitable zone - where liquid water can exist.

If you take a look at their news story, they show our solar system with the habitable zone defined - Venus is too close to the sun to be habitable, but Earth and Mars are both in the right area. This is why they've been sending robots to Mars to look for evidence of past water. Past water, because Mars' atmosphere is much too thin to retain enough heat to have present water, but it does have present ice in the form of its polar ice caps (as well as solid CO2, dry ice).

It remains to be seen whether this planet has an atmosphere which will hold in enough heat to maintain liquid water, but at least its orbit is in the right place for this even to be an option. Composition of some planets' atmospheres (mostly the early Jupiter-sized ones so far) has been studied using infrared absorption spectra, which is a whole level of nifty that I would need to study for a while to understand.

The Voyagers are still going strong

This pair was aptly named. Launched in 1977, the Voyagers are still cruising, still doing science, still sending back photos and data, still occasionally making the news. Just this past summer, they discovered bubbles in the outer edge of the sun's magnetic field, way out at the boundary of the solar system.

The most recent news is more mundane and administrative in one sense, and pretty darn amazing in another sense. The Voyagers have now switched the last set of thrusters to the backup set. Sounds kind of boring, until you realize that this means the longest lasting of the primary set of thrusters lasted for 33 years. Without maintenance. Yeah, try that with your car.

Every time I look at this set of twins, they amaze me. They were designed from the start to be deep space probes; these are the ones who carry the famous golden record (and the needle to play it—yes, it is in fact a phonograph record, only made out of gold instead of vinyl) and took the first ever picture of both the earth and the moon in the same frame. (Links at the bottom of that page to larger versions of the photo.) They're also the only spacecraft ever to have visited Uranus (1986) and Neptune (1989). Everything we know about those two planets beyond distant telescope viewing, we owe to Voyager 2.

Apparently now that they're fully switched to the backup thrusters, they can shut off the heat to the primaries and save power, and expect to get at least another 10 years out of the backup thrusters. Did I mention the backup thrusters weren't maintained for over 30 years either, and they worked fine when NASA turned them on? This just boggles my mind.

I am curious to see what they find when they finally cross out of our sun's area of influence and get into interstellar space, and I really hope their thrusters last that long. (The thrusters in question aren't their drive, they're for aiming the antenna so they can keep talking to Earth.) They just keep on finding new things!

Don't plug the pressure relief valve.

The pressure relief valve is one of my favourite pieces of safety equipment.

In this case, it's just a simple valve that's designed to leak if the pressure gets above a certain point on one side. By letting a small leak happen, you avoid having the pressure get higher than the tank or pipe is designed to handle. If the pressure in a tank gets higher than it's designed to handle, you get stuff like this:

They aren't only on large industrial systems though.

That one was a little bitty (5 gallon, according to the public safety notice I found it on) hot water tank that exploded. A full size hot water tank does a lot more damage, such as done by this 80 gallon commercial hot water tank installed for a school cafeteria. Did I mention you don't ever plug the pressure relief valve? It's there for a reason.

And because it involves explosions, mythbusters naturally did a couple of episodes to find out if a hot water tank really does launch itself like a rocket and if it really can punch through the 2nd floor then the roof of a 2-story house.

So yeah, if your hot water tank has a dripping valve, don't plug it—call the repairman and put a bucket under it until then.

The reverse of a pressure relief is a vacuum relief, which lets air into tanks that you're emptying. Like this one:

Gravitational assumptions

I was working on some fluid flow at work the other day, and while trying to determine whether I could use gravity flow between a series of tanks or whether I had to put a pump in there somewhere, I wondered how a chemical plant built in microgravity would work.

Fluids or solids move because they have potential energy. (Once they're moving they also have kinetic energy.) So what kind of potential energy could, say, a pipe full of water have, if it didn't have gravitational potential and thus couldn't do any kind of gravity flow?

The first thing I thought of was pressure; this is how pumps overcome gravity and lift liquids uphill. Absent gravity, building up pressure at one end of a pipe would push the fluid toward the other, lower pressure end.


Here's a pair of medical terms I have often seen together. One of them I thought I had a moderately good understanding of the meaning, and the other I wasn't really sure exactly what it meant.

As with my previous post in this series, the same comment applies: If a medical doctor happens to read this and notices that I have something wrong, I would be thrilled to get a correction. I'm not a doctor and I'm writing this for other not-doctors; while I'm ok with simplification I don't want to be wrong.

Now, for my pair of terms: mortality is the former; it means how many people die. (Rather appropriate for a Hallowe'en post!) But it's also more than that; it is, specifically, the number of deaths in a given group over a given time period, and what the group and time period is has to be defined. The restrictions make sense, once I stopped to think about it: ultimately, the mortality of humans is 100% - everybody dies of something, at some point. But if you look at the mortality of a disease, or a type of accident, then the group is restricted to the people who have that disease or that injury, and the time is restricted to the time of the study, and the mortality is less than 100%. Something else kills the other people in the study at some other time, not covered by the study.

Acid and oxygen

Acid rock drainage is one of the big environmental problems facing hard rock mines, because it keeps going for decades after the mine is closed and abandoned, poisoning everything downstream with the toxic metals leached from the rock. It's a natural process that occurs wherever rock is exposed to oxygen and water; metal sulphides are oxidized by the oxygen to dissolved metal and sulphuric acid. Exposed rock is eventually consumed until there is little to no unreacted metal or sulphide accessible to oxygen.

However, as the process requires oxygen, it couldn't happen until the earth's atmosphere actually had oxygen in it. I haven't yet found a definitive description of what exactly the earth's atmospheric composition was before the change, but the difference between chemistry with and without oxygen is pretty clear, as oxygen is highly reactive and tends to get into everything. For one, the acid rock drainage I mentioned above. Another indication is the type of iron minerals deposited—with or without oxygen, and how much oxygen. As iron combines very easily with oxygen, if you find an iron deposit without any oxygen there's a good chance no oxygen was available to it at the time it was formed.


I've been following the Science Based Medicine blog for a while now (even though I'm not a doctor) and one of the things I realized is that medical research is a whole lot more complicated than, say, chemistry. In the sort of trials I might do, if you put the same ingredients in a jar, you'll get the same results every time. In medical trials, this isn't the case, because human bodies are a whole lot more complicated than even a jar full of a hundred different chemicals. I sort of already knew this, but some of the articles on SBM have really made this clear to me.

Another thing I realized is that there is a lot of vocabulary around these trials which I only partially understood. So, here is my attempt at explaining this stuff more completely to myself. And, as it says in my sidebar, "I thought I'd share."

(If a medical doctor happens to read this and notices that I have something wrong, I would be thrilled to get a correction. I'm not a doctor and I'm writing this for other not-doctors; while I'm ok with simplification I don't want to be wrong.)

The first one I'm going to cover is clinical trials.

Happy Thanksgiving

I'll be back next week with something. This weekend is for overeating and visiting family, not working and writing.

Simulated Failure

Simulating normal operation is something that's been done for a while now, ever since computers got powerful enough to do it. Once validated, a model of, say, a stirred tank, will let an engineer consider where two liquids being mixed are not mixing properly, or where fragile solids are likely to be broken because the shear is high, and adjust the design accordingly before the manufacturer ever cuts metal.

I started by talking about fluid dynamics simulation because that and chemical reaction simulation are the two aspects I'm most likely to work with. Other simulations which could affect me but are outside of my field are materials and mechanical related - pipe and tank fractures, for example. The stresses and weak points of a piece of equipment are something I have to trust to a mechanical engineer, but I have to think about it at least a bit, because what's inside those tanks and pipes is sometimes hot, sometimes toxic, sometimes corrosive, or other forms of dangerous and undesirable to have present outside the equipment, and I have to know what kind of safety features and procedures I have to put in place, from sensors to detect a small leak to secondary containment to prevent a catastrophic spill from escaping and doing even more damage.


Figuring out where a spatter came from is useful sometimes. Not in any field I've personally worked in, but then I don't usually work with things that go splat. Some things which go splat, where the spatter marks remaining after the fact are the only evidence available to figure out how exactly it happened, include volcanoes (which can make very big, very dangerous splats most sane people wouldn't want to watch in person) and people being attacked (which often ends with the source of the spatter in no condition to describe the attack).

One obvious thing about spatters is that the individual marks are ovals, and they point in the direction of their source. This has been known for a long time now, and has been used in forensics to determine where a victim was. It could also be used for volcanoes, if nobody saw which of the vents erupted due to running for their lives.

What the oval spatters didn't accurately point to was how high the source was.

Biodegrading ... into what?

"Biodegradable" is one of many words commonly used to indicate something is environmentally friendly, but like many technical terms, it often doesn't mean the same thing in common usage as it does to a scientist. To me, "biodegradable" just means that the substance in question can be processed by some biological route into some other, usually lower molecular weight, substance.

It says nothing about the toxicity or harm—or benefit—that might be caused by the new substance.

The Chocolate Process

Chocolate, as you probably know, comes from cocoa trees, but to get from the tree to edible chocolate takes a fair bit of processing. In short, the cocoa beans are removed from the pod, fermented, dried, roasted and shelled, ground, and sweetened.

I can understand why ancient people paid any attention at all to these seed pods; when you cut through the thick rind, the white pulp the seeds are embedded in is delicious straight off the tree. However, the seeds are pretty bitter and nasty tasting when raw. How did they ever go from "suck on this but don't crack the seed open" to "ferment+dry+roast+grind+sweeten = delicious"?

How much does a cloud weigh?

I was chatting with a friend not long ago, and he mentioned that he sometimes pictured clouds as these malevolant, multi-ton monstrosities hovering overhead, just waiting to smash down on us tiny humans. And by the way, how much does a cloud actually weigh?

Clearly, this calls for some math: I decided to calculate how much a cloud actually massed.

I started out by finding a cloud that I could measure reasonably well.


Nano-scale devices have been around for a while now, filling functions such as chemical sensors of extraordinary sensitivity and selectivity, your computer's CPU, and the read/write head on the hard drive. There has also been a lot of progress on what people would recognize as nanomachines, too: motors, gears, switches, all on the nano-scale.

In most cases, however, they're still difficult to make, using the same sorts of high-purity, cleanroom processes as for computer CPUs. Yes, those are in mass production as evidenced by how there are computers in everything these days, right down to doorknobs, but it's still an intensive process requiring extreme purity and cleanroom procedures.

Until recently, that is: some nanoscale devices can now be made easily, even with something as crude as a tabletop vise. Plus, the crucial part, a stamp.

The stamp was made using the cleanroom process, and once complete it can stamp out multiple copies of the actual device outside of a cleanroom, which makes them much cheaper and faster to produce.

One thing that is particularly interesting to me as a chemical engineer is how simply changing the coating on the nanostructured surface (for example, a tiny diffraction grating) changes what chemicals it detects (or more specifically, what chemicals stick to it). Then, on shining a light on it, the presence of those stuck chemicals changes the reflection or diffraction pattern in a way that's proportional to the amount of chemical adsorbed. And, moving outside of my field of expertise, biological molecules can be very specific in what will stick together and what will not. There's a lot of work going on to make these sensors to detect specific enzymes or enzyme activity that are characteristic of a disease, antibodies, and even parasites.

Making these sensors faster and cheaper means that development of useful tests for hospitals, and maybe eventually your GP's office, will speed up dramatically.

Life-giving crystals

Another piece of the puzzle that is life has fallen into place, and it is a spiky crystal.

That right there is one powerful crystal: it is the chemical precursor to RNA, the earliest self-replicating molecule that science is aware of, and thus the starting point for life. It grew from a mixture of basic, common organic chemicals in the presence of a few common amino acids, and is stable and will stay put until the next step, converting it to RNA, takes place.

Not only that, but it's the correct form of the two possible enantiomers that the RNA precursor can take, and it grew naturally out of a mixture of chemicals that didn't start out composed of the pure correct enantiomer, but of a racemic mixture plus a nearly racemic mixture of amino acid that had only 1% excess of the enantiomer they wanted.

I am not a flower

I was on a job site, walking outdoors, when something small and bright moved near my shoulder. My first reflex was to swat at it; there are no lack of wasps around here. Fortunately I managed to stay my hand when I recognized it—a bright yellow butterfly, exactly the same colour as my yellow safety vest.

It landed on my vest, took off, landed, took off, and kept doing that for about a minute.

"Sorry, butterfly, I'm not a flower," I said to it, standing still next to the reactor.

It landed on me a few more times, then eventually realized I wasn't actually a jackpot of a bright yellow flower, and flew away.

My co-workers probably think I'm crazy. I've rescued a ladybug from one of the tanks in the same plant. As it was walking all over my hand the way ladybugs do, one co-worker asked me why I was talking to a bug.

"I like ladybugs," I said. "They eat the bugs that eat my garden."

We've also rescued a small frog from one of the tanks, and chased another out of its daytime hiding spot inside a short length of 1/2" PVC before using it. On moving an orange road cone, another co-worker commented that he was going to go fishing, after catching some of the explosion of crickets that burst out when the sun hit them.

Despite all that, I don't like it when wasps build nests on my equipment. They're the only ones I'll get out the killing spray for—not because I have something against wasps, only that they can't be building nests on my equipment when people need to be working in that area. They can build their nests somewhere else. Unfortunately, convincing them not to keep rebuilding in the same spot requires that killing spray. I hope after hitting two nests they're getting the idea.

Inspired by: water striders

Here's another small robot that illustrates a fundamental property of physics. Like the Waalbot I mentioned last week demonstrated van der Waals forces, this one demonstrates surface tension.

Above is a water strider. Notice the dimples in the water where each foot touches the surface of the water.

Inspired by: geckos

This bit of news isn't actually all that new, but that's the nature of science: from discovery of physical principle to practical application takes a while.

So way back in the '70s, there was finally a microscope powerful enough to see what a gecko's hairy feet looked like. Because however they managed to climb polished glass, it wasn't glue, it wasn't suction cups, and it wasn't hooks or claws. This is what they found:

Yup, those are some hairy toes.

Sunshine and sharpies

With a sheaf of drawings in one hand and a felt marker in the other, I wandered through the plant. It was stinking hot, but I'd rather be out here than in the air-conditioned trailer; I had to be outside anyway, and every stop in the trailer is one more shock to the system that I didn't need. Acclimatization makes the temperature easier to bear, but not all of my co-workers believed that and they kept the office trailer cold. I know colds are caused by viruses, but the co-worker who spent the most time in the trailer and turned the air conditioner the coolest was also the only one of the crew who caught a cold.

The pipefitters had almost finished with the large pipes, and would be starting on the small pipes soon after, which is why I was out with the marker. Nobody told me in school that felt markers would be an important part of the engineer's toolkit.

Since any given tank might have a half dozen ports all the same size, and some of them are very specifically placed where they are for a reason, they can't just be hooked up willy-nilly. This was why I was standing on top of a tank in the hot summer sun this time. No gas masks needed this time, fortunately, as this was still a construction site and nothing toxic had been introduced anywhere yet.

I'd study the tank drawing for the tank I was standing on, re-verify that the ports were all placed and sized properly, then kneel beside a port and write the port number and connection beside it with the sharpie. After burning my knees on the sun-hot metal of the tanks, I'd tug my pant legs up so the holes weren't directly under my knees. Nobody told me in school that burnt knees were a hazard of the field, either!

I marked every single port, and killed more than one marker doing it. Not so much that it was a giant plant, as the markers just didn't last long, writing on hot metal out in the sun—maybe a tank and a half to two tanks per marker. Tedious jobs are part of engineering, and while I don't particularly enjoy them, it is good to just put your head down and plow through them and then they're done. And, in this case, once finished I wouldn't be interrupted repeatedly by the pipefitters asking me which pipe went where.

The next day, as I wandered around the plant to see the piping progress, my markings had faded dramatically. It wasn't many days until they were nearly gone. Well, I tried.

Hydrophones at depth

Here's a nifty new piece of technology from Stanford University for any ocean-science types: a hydrophone that can be used at any depth which has low-distortion sound detection over a dynamic range of 160dB and a frequency range of 1Hz to 100,000Hz. By contrast, the human ear can hear a range of about 20-20,000Hz, feels immediate and acute pain at about 120dB—chronic damage starts much lower, down about 85dB. (If you want to know what 120dB feels like, stand about 3m in front of an emergency vehicle with its siren sounding.)

Most microphones have a thin diaphragm which vibrates in response to the sound waves hitting it, and this one is no exception. However, when you're detecting tiny pressure changes against the crush of a deep ocean trench, you need something that will not be overwhelmed by the ambient pressure. The answer for this particular microphone was to drill tiny holes in the diaphragm so that the water pressure on both sides of the diaphragm is the same. The holes would have to be small enough that sound waves in the water wouldn't pass right through them without moving the diaphragm, and large enough that the pressure would equalize before damaging the diaphragm as it's brought to depth. The diaphragm itself is about 500nm thick, so it is very fragile. To measure the movement of such a fragile surface, they use a laser. This is highly accurate and also doesn't touch the diaphragm with anything other than light. At the quiet end of the sounds they wanted to measure, and with water resisting the motion of the diaphragm, it moves only about 0.00001nm or so. Fortunately, lasers and mirrors can detect that sort of tiny movement.

Different sizes of diaphragms (and drumskins, and sound boards, and strings, and horn tubes) are most responsive to a particular frequency, so to cover the full range of frequencies they wanted to hear without distortion would be tricky with only one diaphragm. So, they put three different sizes of diaphragm in one microphone to cover the range.

Delayed effects

Pin holes in my jeans, above the knee. How did that happen? I don't remember them being there before I put them in the laundry. There were a half dozen on each thigh, ranging in size from just a few broken threads to something I could put a pencil through.

I wore them anyway; they're my work grubbies, intended to get dirty or damaged.

While titrating a sample, I realized a possible route to those holes. The sample was about 2 litres; the chemical dropped in from well above the edge of the container. If micro-drops had splashed back out, unseen, and landed on me, the chemicals involved could have eaten holes in my jeans. But I hadn't noticed them until after doing laundry. After getting them wet.

Here's a funny paradox for you: 98% sulphuric acid is safer (or at least easier to store) than 50% sulphuric acid. Why? Because 98% doesn't have enough water in it to dissolve the acid and activate it. Not saying it isn't still very dangerous stuff: it is, and if water gets in the tank you're in trouble.

Maybe the chemical droplets stayed on my jeans until the water activated it enough to eat a bit of the fabric, until the wash cycle diluted it to the point where it couldn't do anything anymore.

I think it's time for a lab coat. Must ask the boss for one. It's safety gear!

New medicine from old

Traditional medicines can be interesting things. Some don't work at all despite being widely used, but some, like the bark and leaves of willow (Salix), work very well and have been effectively used for millennia—there are written records from 500 BC referring to its use. More recently (the 1820s) the active ingredient, salicylic acid, was produced, then in the 1890s acetylsalicylic acid, what we know as modern aspirin or ASA, was created. Aspirin no longer comes from plants as willow trees can't grow fast enough to sate the world's appetite for painkillers, but is now synthesized from phenols.

Another traditional painkiller, a milkwood (Tabernaemontana) has been under investigation for several years now. According to the studies, it contains a mixture of several things, including compounds in the class of opioids (a painkiller type which tends to have undesirable side effects and which causes addiction) and conolidine, among many others.

The conolidine and other compounds were isolated and identified in 2004, but conolidine couldn't be properly studied at that time because they only managed to get a 0.00014% yield when purifying it out of the plant. In May 2011, a team of researchers from the Scripps Research Institute announced that they had not only managed to synthesize conolidine, they had also tested it on mice and found out that it had painkiller effects as strong as morphine, but without any of morphine's adverse side effects.

Identified Hovering Objects

Just pretty pictures today; the post I had been planning on for today is turning out a bit more complicated than I had figured. This will probably happen again. That's the thing about learning new stuff... it always takes longer than you think it will.

Sao Paolo



There's nothing quite like standing on top of a tank in the hot summer sun, surrounded by other tanks all reflecting the heat back up at you. Except, maybe, if you're wearing a full face gas mask and taking samples of a gas that is just about everything bad you can call a chemical.

Toxic, corrosive, flammable, explosive, carcinogenic… The whole system ran at a slight negative pressure, so that if there were any leaks air would go in instead of toxic gas leaking out, and they monitored it carefully to keep the concentration out of the explosive range.

I was testing the performance of a new scrubber which was taking the gas in question out of the exhaust, so I had to climb up to the top of the tanks then up on a scaffold, carrying a vacuum flask, to stand next to the exhaust stack and suck a sample out of the flow. All around me were explosion hatches; small explosions ("puffs") were undesirable but routine, and there was a well-established procedure for re-starting the system after it shut itself down following a puff.

For all that, it was pretty safe: as safe as it could be, considering the material. One day when I was taking a sample, a puff happened while I was on top, and I barely noticed it. I think I heard a bang as the explosion hatches jumped, but by the time I turned to look they had fallen back into place and re-sealed the tank, exactly as they were designed to do.

The gas mask was uncomfortable, but I was happy to be wearing it. It sealed all around my face, forehead to chin, and the sweat it generated improved the seal. I couldn't wipe the sweat off my face however, and it's no fun to get sweat in your eyes while you're climbing around a scaffolding system.

After a couple of weeks of this (I could only take one in/out sample set per day, and if there was a process upset that day I had to throw my results out) I noticed that my hair smelled … strange. For all it was a treated gas stream, with low levels of the toxic chemical, I had been spending enough time exposed to it that the gas had started doing something to my hair. The smell was that sickly-sweet smell of rotting fruit, and it lingered for a week or so after I finished that particular project. It took a few washes before the smell finally went away.

That smell in my hair was the only effect the gas had on me. Gas masks are wonderful things.

Getting lost in the stacks

I'm in trouble now…

I recently discovered a black hole as deep as the internet for losing time in, but which is much more edifying - so I don't feel so bad about all the time spent there because I'm learning stuff.

How useful that stuff is has yet to be determined.

We begin with Google Scholar. This is a corner of google's search engine that is focussed exclusively on technical journals and peer-reviewed publications. It's fantastic if you're looking for technical information about something that is also for sale; regular Google would be massively polluted by people selling that something, or asking for help about that something, or reviews of that something, or blogging about that something. There's just one catch, and it's a big one: the journals are almost all pay sites.

Oh, they let you read the abstract, and sometimes you're just doing an overview and that's enough. But at $30 per article or more, it can get expensive really fast if you're actually trying to dig into a subject. On top of that, if you're looking for something specific like the solubility of a relatively obscure compound (by 'obscure' I mean it's not on wikipedia), the information may not be in the abstract.

Then I remembered from my student days that the university library had a proxy which students could log in with and which would give full, free, institutional access to most of these pay sites. Of course the university would have a subscription! Of course, I'm not a student anymore.

After a bit of investigating, I discovered that my old student number was still in the university's system, and I successfully logged in to the proxy and downloaded a few papers that I'd put on my "to get" list.

Next thing I knew, it was three hours later, I'd downloaded a dozen related papers, was having a grand time reading them and following references—and I was still at work.

Fortunately, I was looking up information related to one of my projects at work and some of the interesting stuff I'd read might help the project, so I knew the boss wouldn't mind. Too much.

Now I have a bookmark to Google Scholar via the library proxy in my browser's bookmark bar which takes me to the proxy login page then to the search engine, so that every link I click on in the results goes straight to the full article.

I think I'm in love.

Snow eater

The Chinook wind is a warm dry wind that comes down from the Rocky Mountains into Alberta, and can turn a winter day into short-sleeve weather in the space of hours. But what heats up the air? It wasn’t that warm on the BC side of the rockies, before it crossed the mountain range. Well, I decided that I was going to calculate it. Let's see if this works.

Let’s say the air comes off the ocean at about 10 degrees Centigrade and 90% relative humidity, which isn't actually typical for a dreary Vancouver winter day—but that's because the Chinook is powered by the Pineapple Express, which is warm, wet air coming inland from Hawaii. It travels inland, raining on Vancouver as it goes, until it hits the coast mountain range, and is forced to rise.

You’ve probably noticed, if you’ve ever changed altitude quickly, that it gets colder the higher you are. Well, that wind from the ocean is going to do exactly that.

To do the math, we’ll look at a small piece of the wind, pretend it stays together to simplify things, and follow it over the mountains.

Vitamin C makes you not dead

I'm sure you've all heard the story of how vitamin C either prevents or cures the common cold. Some of you may also remember that vitamin C prevents or cures scurvy. But what exactly does it do for our bodies? I decided to do a bit of searching and find out.

Clues to what vitamin C does for us can be found in the symptoms of vitamin C deficiency itself. Scurvy is not just the disease where your teeth fall out, though that is one of the symptoms. Bleeding gums, bleeding under the skin (bruising), bleeding in the joints (joint pain), bleeding at hair follicles, and bleeding at previously healed scars start off the list of visible symptoms. Before those is fatigue; after those is death.

All of those bleeding symptoms demonstrate that the body is falling apart and can't keep its blood inside anymore. Quite literally: vitamin C is required for the production of collagen, the structural support cables of our body. They're found basically everywhere, including in bones and teeth, where they're mixed with minerals. Lose the ability to make new cables, and you lose the ability to repair routine damage day to day - and over time you lose the microscale structural integrity that keeps the blood inside your veins, among other things.

Fatigue is so general a symptom it can't really be used to diagnose anything. Besides, you probably just stayed up too late. But even here, it seems that vitamin C plays a role. In addition to being crucial to making collagen, it's also crucial to making dopamine, norepinephrine and epinephrine (adrenaline), and carnitine.

Carnitine is an escort for fatty acids into the mitochondria, according to the link above. Basically it's the fuel injection system for the motors that power our cells. While we get most of our carnitine from our diets, particularly from meat, if we're so low on vitamin C we're suffering from scurvy, we probably have low carnitine intake as well, a double-whammy.

But carnitine is in meat, and vitamin C is in oranges and other tasty veggies and fruits, right? How could the inuit survive on a meat-only diet? Actually, there's vitamin C in meat, too: mostly in organ meat, and the inuit do just fine without vegetables, on their traditional diet.

In fact, it looks like just by eating a reasonably healthy mix of food, you'll get enough vitamin C. Not everybody manages this, but I guess scurvy is rare enough now that people forget about the whole "it keeps you alive" part and instead spend their time thinking about some of its very minor effects.

As for curing the common cold? survey says… taking it when cold symptoms appear does no better than a placebo; taking it every day reduces cold duration by maybe 10%; and if you're physically stressed (i.e., working in a cold climate or running marathons, not just worried) then taking it every day can be justified because it gives significantly more than a 10% benefit.

Saturated gas masks are worse than useless

Activated carbon is a pretty amazing material. It's just carbon, the same stuff as in charcoal, diamond, and the carbon black that shows up on the bottom of pans and kettles used over flame, for those who have gas stoves or enjoy camping. At the same time, it's an incredibly important material for purification, because one of the neat things that activated carbon does is trap toxic stuff by adsorption. It doesn't catch everything, but it catches so many different things that it's often used in gas masks when you don't know what toxic gas you might encounter - for a HazMat team, for example, those who aren't using SCBA tanks.

One unfortunate problem with any filtration system is that the filter itself has a limit to how much crap it can capture from the water or air that's passing through - and the filter can't tell you when it's getting full. How do you know when it's time to change your Brita filter? How does a HazMat team know when their gas masks stop working? In a plant situation with large equipment, you can install sensors to monitor for breakthrough, but that's not practical, and sometimes not even possible, on small portable filtration systems.

A team from the University of California San Diego recently published in the journal Advanced Materials a paper on the production of carbon nanofiber photonic crystals. These are a special crystal form of carbon which, once they've captured toxins, change colour. No power required, no special equipment required, no extra weight for HazMat to carry. These crystals can be embedded right in the activated carbon filter, so they see exactly the same level of toxin as the filter itself. If you embed them at varying depths in the filter, you could actually watch the adsorption front as it moved through the filter, and know with certainty when your filter is getting close to breakthrough, and thus when it needs to be changed.

Up, up, a little bit higher

In honour of today's shuttle launch, I thought I'd start off with a bang, or at least a roar of fire: rocket fuel!

The shuttle uses two different styles of rockets with two very different types of fuel: liquid and solid. The shuttle itself has three big rocket engines that run on liquid hydrogen and liquid oxygen, stored in the big orange external tank, while the rest of the thrust is provided by solid fuel in the solid rocket boosters, a mixture of ammonium perchlorate (NH4ClO4), aluminum, iron oxide, and some binders to hold it in its moulded shape.

The liquid fuel engines fire first; they are the controllable ones. If there's a problem, they can be shut down. Once the solid fuel starts burning, they only stop by running out of fuel - and the solid rockets provide the majority of the boost to get the shuttle off the ground.

And since this is a chemical engineer's blog, I'm going to do some calculations around the chemistry of those engines. Of course, this won't be nearly enough to design your own rocket engine from, but then I'm just doing this for fun, I'm not a rocket scientist.