The aim is to produce zinc sulfide crystals doped with copper impurities. This creates a phosphor with a familiar green glow. [Hydrogen Time] starts by noting that it’s important to make sure all chemicals used are of good quality, as even slight impurities can spoil the final product.
Zinc sulfide is made into an aqueous solution, before a highly diluted copper sulfate solution is added, along with ammonium chloride to act as a flux. The mixture is stirred, before being heated in a tube flushed with argon. After firing, the phosphor is washed with water and allowed to cool.
Love it or loathe it, the pharmaceutical industry is really good at protecting its intellectual property. Drug companies pour billions into discovering new drugs and bringing them to market, and they do whatever it takes to make sure they have exclusive positions to profit from their innovations for as long a possible. Patent applications are meticulously crafted to keep the competition at bay for as long as possible, which is why it often takes ages for cheaper generic versions of blockbuster medications to hit the market, to the chagrin of patients, insurers, and policymakers alike.
You’d be hard-pressed to walk down nearly any aisle of a modern food store without coming across something made of plastic. From jars of peanut butter to bottles of soda, along with the trays that hold cookies firmly in place to prevent breakage or let a meal go directly from freezer to microwave, food is often in very close contact with a plastic that is specifically engineered for the job: polyethylene terephthalate, or PET.
For makers of non-food objects, PET and more importantly its derivative, PETG, also happen to have excellent properties that make them the superior choice for 3D-printing filament for some applications. Here’s a look at the chemistry of polyester resins, and how just one slight change can turn a synthetic fiber into a rather useful 3D-printing filament.
If you have something rusty, you can get a wire brush and a lot of elbow grease. Or you can let electricity do the work for you in an electrolysis tank. [Miller’s Planet] shows you how to build such a tank, but even better, he explains why it works in a very detailed way.
The tank uses a sodium carbonate electrolyte — just water and washing powder. In the reaction, free electrons from the electrolyte displace the oxygen from the rusted metal piece. A glass container, a steel rod, and a power supply make up the rest.
The action at the molecular biology bench boils down to a few simple tasks: suck stuff, spit stuff, cool stuff, and heat stuff. Pipettes take care of the sucking and spitting, while ice buckets and refrigerators do the cooling. The heating, however, can be problematic; vessels of various sizes need to be accommodated at different, carefully controlled temperatures. It’s not uncommon to see dozens of different incubators, heat blocks, heat plates, and even walk-in environmental chambers in the typical lab, all acquired and maintained at great cost. It’s enough to discourage any would-be biohacker from starting a lab.
[Justin] knew It doesn’t need to be that way, though. So he tackled two common devices: the incubator and the heating block. The build used as many off-the-shelf components as possible, keeping costs down. The incubator is dead simple: an insulated plastic picnic cooler with a thermostatically controlled reptile heating pad. That proves to be more than serviceable up to 40°, at the high end of what most yeast and bacterial cultures require.
The heat block, used to heat small plastic reaction vessels called Eppendorf tubes, was a little more complicated to construct. Scrap heat sinks yielded aluminum stock, which despite going through a bit of a machinist’s nightmare on the drill press came out surprisingly nice. Heat for the block is provided by a commercial Peltier module and controller; it looks good up to 42°, a common temperature for heat-shocking yeast and tricking them into taking up foreign DNA.
We’re impressed with how cheaply [Justin] was able to throw together these instruments, and we’re looking forward to seeing how he utilizes them. He’s already biohacked himself, so seeing what happens to yeast and bacteria in his DIY lab should be interesting.
Compared to incandescent lightbulbs, LEDs produce a lot more lumens per watt of input power — they’re more efficient at producing light. Of course, that means that incandescent light bulbs are more efficient at producing heat, and as the days get shorter, and the nights get colder, somewhere, someone who took the leap to LED lighting has a furnace that’s working overtime. And that someone might also wonder how we got here: a world lit by esoteric inorganic semiconductors illuminating phosphors.
The fact that diodes emit light under certain conditions has been known for over 100 years; the first light-emitting diode was discovered at Marconi Labs in 1907 in a cat’s whisker detector, the first kind of diode. This discovery was simply a scientific curiosity until another discovery at Texas Instruments revealed infrared light emissions from a tunnel diode constructed from a gallium arsenide substrate. This infrared LED was then patented by TI, and a project began to manufacture these infrared light emitting diodes.
Battery cells work by chemical reactions, and the fascinating Hybrid Microbial Fuel Cell design by [Josh Starnes] is no different. True, batteries don’t normally contain life, but the process coughs up useful electrons all the same; 1.7 V per cell in [Josh]’s design, to be precise. His proof of concept consists of eight cells in parallel, enough to give his cell phone a charge via a DC-DC boost converter. He says it’s not known how long this can be expected to last before the voltage drops to an unusable level, but it works!
There are two complementary sides to each cell in [Josh]’s design. On the cathode side are phytoplankton; green micro algae that absorb carbon dioxide and sunlight. On the anode side are bacteria that break organic material (like food waste) into nitrates, and expel carbon dioxide. Version 2 of the design will incorporate a semi-permeable membrane between the cells that would allow oxygen and carbon dioxide to be exchanged while keeping the populations of micro-organisms separate; this would make the biological processes more complementary.
A battery consisting of 24 cells and a plumbing system to cycle and care for the algae and bacteria is the ultimate goal, and we hope [Josh] can get closer to that now that his project won a $1000 cash prize as one of the twenty finalists in the Power Harvesting Challenge portion of the Hackaday Prize. (Next up is the Human Computer Interface Challenge, just so you know.)