Titanium (Ti). A transition metal with 22 protons. It's strong, light, and corrosion resistant. These are objective characteristics that make it superior to many other materials for many applications. Yet, this metal (or at least its marketers) is as self-conscious as a sweatpants-wearing middle schooler. I have never seen a piece of titanium anything that wasn't branded. Camping cook-ware, bike frames and bits, my brother's wedding ring-they all say "TITANIUM" (usually in all caps) or sometimes just "Ti" somewhere on their under or backsides. I ended up with some titanium crank bolts. Both the male and female halves proudly proclaim "TITANIUM." This poor metal thinks that without its eight-lettered moniker, people wouldn't be interested in paying three times more for items made out of it. On the other hand, the name is pretty awesome. If titanium didn't exist, Marvel Comics would have invented it to reinforce Wolverine's skeleton instead of adamantium.
Now on to another metal. Nickel (Ni). This one has 28 protons. It's also a transition metal but is heavier than Ti. It's the stainless part of stainless steel and, mixed with iron makes up the earth's core. It's been used since 3500 BC (according to Wikipedia) and, since 1983 it is an essential nutrient for plants. Why did it take us so long to figure out plants needed Nickel you might ask? After all, we had isolated the other nine essential plant micronutrients by 1954. Well, the answer is a sneaky one.
The way you determine an element is "essential," is by attempting to grow plants without it. There are lots of elements which enhance plant growth or yield but without which plants can still complete a normal life cycle. I love the plant ecologist term for this: luxury uptake. In the early 20th century agriculturists started growing plants hydroponically-that is, without soil. Plants don't take up anything directly from soil, in fact they can't take up any solid materials whatsoever. Even when rooted comfortably in their usual brown, they derive their nutrition from the soil by way of soil water and their carbon and oxygen from the air. The soil, as long as you can keep the soil water nice and nutritious, is actually unnecessary. Without the dirt, you have a highly controllable plant environment in which to test plant requirements. Since you've deprived the plant of its normal pantry (soil), it only gets what you feed it.
So, these farmer-scientists started systematically depriving plants of various elements.
"Oops Dave, your beans died when you took away Boron, put that on the list."
"Looks like they need Chlorine too, who'd have though?" and so it was with molybdenum, selenium, zinc, manganese, copper, iron, and sodium (you know, maybe titanium is so insecure because nobody needs it).
So why not nickel? Here's a picture from Dave Eskew's 1983 study that finally put nickel on the nutrient map. Panel A, on the left side is a picture of a soybean plant grown with no nickel. Wait a minute. It looks basically fine! Panel B on the right shows a plant after several generations of Nickel deprivation--also not looking too shabby. As Matt says, "WT Heck!"
If you take the beans produced by the Nickel-deprived plants and plant them in a nickel-free environment, they grow fine. If you take the beans from that generation and grow them . . . and so on and so on until the fifth generation (or somewhere thereabouts). After five generations of this nickel fast the plants develop dead spots (necrotic lesions), particularly in the leaf tips. When Dave's group analyzed the dead spots they found elevated Urea concentrations. Urea is a nitrogen compound found in--well, urine. It's created in normal plant nitrogen metabolism and it's usually super yummy for plants. Excess urea needs to be broken down, and the plant does this by an enzyme that contains. . . NICKEL!
So, why didn't urea build up in the first generation? Well, the answer lies in an erroneous experimental assumption. The investigators assumed they had blocked all nutrient inputs to the seed except for known elements they they added through the hydroponic solution. However, they hand' t taken into account the seed's own tissues. There is enough nickel in any given soy bean (or mustard seed or maple whirligig) to furnish the whole plant with urea-chomping enzymes. In the absence of external sources, when the plant gets itchy for nickel it harvests its own tissues and moves the element where it needs (a process called translocation). Enough of this translocated nickel gets into the next set of seeds that those plants can scrape by and so forth unto the fifth generation!
So everything looks fine for generations and then, all of a sudden, the plants die. Isn't that terrifying? I mean what sort of masked deficiencies am I suffering from (either inherited from my parents or invented by my own peculiarity)? How long will it take to reveal my anemia, and how many people will see me in my apparently hunky-dory state and think, "I guess XYorZ isn't necessary to happy human functioning!"?
Well I guess that's why God invented blogs right? That way we'll catch wind when somebody develops necrotic lesions and we can comb their posts to find out what they stopped eating.
On a different note, here's a headlight I made for winter bike riding. I got the parts off dealextreme.com for $30 (when you see the sight your first thought may be "they are going to steal my credit card info"--that's what I thought, but they turned out to be legit), and used a broken camera tripod for the mount. It puts out 500 lumens, will run for six hours on high, and has rechargeable Li-ion (speaking of metals!) polymer batteries that function well down to -70F. We usually don't get much below -50F so I should be fine.
