August 31, 2013

Special Request: Looking at Your Own DNA in your Kitchen.

This week, I got a special request.  It was to post instructions about how to isolate a sample of one’s own DNA at home.  It is not only possible, it is easy.  And very fun.  And there is no experience more bonding than sitting around with someone for 20 minutes, spitting into a glass. (Seriously.)  SO: Start with about 1 tablespoon of your own spit (or someone else’s, or mix them up.  Whatever.)  Add about 1 tablespoon of water, one drop of dishwashing liquid, and a shake of salt.  Mix vigorously, preferably with a plastic utensil.  What is happening here? The soap is breaking open the cells that are present in your saliva and the DNA is coming unspooled (like reeling the tape out of a cassette).  Wait for 5 minutes, then gently pour 91% isopropyl alcohol down the side of the glass to create a 2 layer effect (this is not difficult).  What happens next?   Water, which is very happy to be clinging to DNA, is MUCH happier clinging to the alcohol.  This “dehydrates” the DNA causing it to tangle up and precipitate in the alcohol layer.  The white cottony looking fluff in the alcohol is your DNA.  And yes, this is exactly the way we do it in the lab - the chemicals are cleaner, the purity is higher, but the precipitation with alcohol is just the same.  Even in the lab I never get tired of watching this happen.

January 25, 2013

January 16, 2013
In which we field a cool chemistry question from a bee-keeper relative.
A bee-keeping relative had a question for me recently.  Over the winter, he feeds the bees by mixing up table sugar with water, making it acidic (with vinegar) and heating it.  His question was: what is happening chemically?  WELL: as it turns out, he is making invert sugar.  Invert sugar is really a term from baking, but chemically the process he is doing is called “hydrolysis.”  Table sugar is mainly sucrose. One sucrose molecule is actually made up of 2 simpler sugars bound together chemically - one glucose molecule and one fructose molecule. By acidifying and heating the sucrose, it is broken apart into two separate molecules. Scientifically, this is called hydrolysis - using water (hydro) to cut (lysis) the sucrose molecule in half. So the thing I did not know (which I have never thought to wonder, so I looked it up!) is that honey gets its sweetness from glucose and fructose. So then the whole thing comes together: by acidifying and heating the table sugar, you are making it into something very similar to honey. I bet the bees love it.  Here, Ophelia and I put the sugar mixture onto glucose detecting test strips before and after heating.  And it works!

In which we field a cool chemistry question from a bee-keeper relative.

A bee-keeping relative had a question for me recently.  Over the winter, he feeds the bees by mixing up table sugar with water, making it acidic (with vinegar) and heating it.  His question was: what is happening chemically?  WELL: as it turns out, he is making invert sugar.  Invert sugar is really a term from baking, but chemically the process he is doing is called “hydrolysis.”  Table sugar is mainly sucrose. One sucrose molecule is actually made up of 2 simpler sugars bound together chemically - one glucose molecule and one fructose molecule. By acidifying and heating the sucrose, it is broken apart into two separate molecules. Scientifically, this is called hydrolysis - using water (hydro) to cut (lysis) the sucrose molecule in half. So the thing I did not know (which I have never thought to wonder, so I looked it up!) is that honey gets its sweetness from glucose and fructose. So then the whole thing comes together: by acidifying and heating the table sugar, you are making it into something very similar to honey. I bet the bees love it.  Here, Ophelia and I put the sugar mixture onto glucose detecting test strips before and after heating.  And it works!

January 8, 2013



In which Ophelia and I Microwave a Bar of Soap

This is half of a bar of Ivory soap in the microwave for 1 minute.  The reaction is quite dramatic.  But so is the resulting smell - so you have been warned.  (Oh, and it has to be Ivory - Dove soap melts into a fuming puddle of caustic goo.)

November 8, 2012

A Stand for iPhone/iTouch

While using Skype, it is easy to cause motion sickness in the other party if the iPhone or iTouch is waving around, because, say, it is being held by an 8 year old.  Enter the iTouch Stand.  We started with a simpler one cut from a cereal box, and it worked well.  This one is made from basswood, white glue, white paint, and green Sugru.  It works really well.

October 29, 2012

In Which Ophelia and I Make Our Own pH Measuring Stuff From Cabbage

Recently, I got some litmus test strips and Ophelia and I have been pHing everything in the house.  It has been a fun adventure.  While researching this, I learned that some common foods have colorful dyes in them that can act as pH indicators.  The most commonly mentioned is red cabbage, which contains an anthocyanin pigment called flavin that changes color according to pH.  We bought a red cabbage, boiled about half of it in an inch of water for 20 minutes and then collected the juice.  In order to use it, we took about 2ml of the juice, added  8ml of water, and then about 2 ml of the test material.  The package of the fancy pH strips has a color guide to compare the strips to, but there is no cabbage scale available, as far as I know.  We decided to make one ourselves.  The pH values on the card were measured with the strips and marked here for reference. The color in the squares is Ophelia’s best attempt to imitate the liquid using colored pencils.  The values seem to go from yellow/brown (basic) through cyan, then purples, then pinks (acidic).  The next logical thing to do would be find some “unknowns” and try to call the pH using the cabbage juice.  I am really quite surprised that this solution responds, seemingly, across the entire range.  Turmeric is next.  I will let you kow how it goes.

October 29, 2012

In Which Ophelia Proves the Relationship Between Elevation and the Partial Pressure of Gases


This summer we left our humble position here near the sea to visit the lofty heights of the Rocky Mountains.  Before leaving, I picked up an accurate thermometer at the homebrewing shop here in town.  At home near Boston (elevation 177 feet), water boils at 212° F.  This is the “sea level” temperature we all learn in school.  At our first stop in Colorado - a town called Highland’s Ranch - the elevation is 5,736 feet.  It’s more than a mile high.  And water boils at 202° F.  Our next stop was a town called Larkspur at 6,714 feet above sea level.  Water boils at 200° F there.  We did take one hike that put us above 10,000 feet, but alas, we did not bring a stove with us.  Ophelia recorded the data and made a graph.  Now we can draw a line, make some predictions, and then try to find some friends at 2,000 and 3,000 feet to visit and see if our model holds up.  

October 29, 2012
In Which We Take the pH of Everything
I got some fancy litmus test paper strips from Fisher Scientific.  It is fun to own something that is more often an analogy than a thing - but I digress.  We started pHing everything in the house - trying to guess which would be acidic and which would be basic.  There are a lot more acidic things in the house so far.  And bleach?  It bleaches litmus paper.

In Which We Take the pH of Everything

I got some fancy litmus test paper strips from Fisher Scientific.  It is fun to own something that is more often an analogy than a thing - but I digress.  We started pHing everything in the house - trying to guess which would be acidic and which would be basic.  There are a lot more acidic things in the house so far.  And bleach?  It bleaches litmus paper.

July 7, 2012
The Shortest USB Cable in the World
In today’s mail I got the shortest USB cable in the world. It makes me SO happy. I have been programming my Arduino microcontroller board with a long flippy floppy printer cable. Silly Me. It is so awesome to have just the right tool.  (It is actually a USB type A male to USB type B male adapter.  But it works like a cable.)

The Shortest USB Cable in the World

In today’s mail I got the shortest USB cable in the world. It makes me SO happy. I have been programming my Arduino microcontroller board with a long flippy floppy printer cable. Silly Me. It is so awesome to have just the right tool.  (It is actually a USB type A male to USB type B male adapter.  But it works like a cable.)

May 16, 2012

A Rotary Dial Bluetooth Telephone

I have seen a number of rotary phone-to-Bluetooth or rotary phone-to-cellphone conversions on the web, I thought I would try my own.  First step, figuring out how the phone works.  This has been pretty amazing because all of the sequenced and ordered events that happen when you pick up and dial this phone happen mechanically.  Very elegant (and requires 0 amps).  Second, let’s just see if I can hook this old handset up to the old Jabra ear-thing and see if it works: it does (I added a parallel 300 ohm resistor to the mic tone it down a bit).  Next step, figure out the receiver switch and make it a “momentary” action to pick up and hang up calls from the ear-thing.  I think I am close: stay tuned…

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