ChemSpider screenshot

ChemSpider entry for caffeine

ChemSpider is a chemical structure database by the Royal Society of Chemistry (RSC) that provides access to over 50 million molecules, properties, and associated information from over 500 data sources including US Food and Drug Administration (FDA), Kyoto Encyclopedia of Genes and Genomes (KEGG), Molecular Diversity Preservation International (MDPI), US National Institutes of Health (NIH), US National Institute of Standards and Technology (NIST), Structural Genomics Consortium, Thomson Pharma, and Web of Science. By integrating and linking compounds from these data sources, ChemSpider provides a comprehensive view of freely available chemical data in a single online search.

A number of available search modules are provided, including the use of mobile devices via free apps for iOS and Android, allowing for querying systematic names, trade names, synonyms, and registry numbers. The advanced search allows interactive searching by chemical structure, chemical substructure, using also molecular formulas and molecular weight ranges, Chemical Abstracts Service (CAS) registry numbers, and suppliers.

interactive 3D model of caffeine 1
interactive 3D model of caffeine 2

This can be done because each chemical is given a unique identifier, which forms part of a corresponding URL, e.g., caffeine (1,3,7-Trimethyl-3,7-dihydro-1H-purine-2,6-dione) is 2424 and thus has the ChemSpider URL

Besides offering a static, two-dimensional structural formula of the molecule, ChemSpider also offers an interactive three-dimensional model which can be viewed via Jmol (using a Java applet) or JSmol (a JavaScript framework for Jmol to display on devices that do not have Java installed or for which Java is not available, e.g., smart phones and some tablet computers).

Where’s George?

I heard about this website Where’s George? that tracks the circulation of US dollar bills and other paper currency for fun. Since I am interested in networks and the flow of information, I decided to check it out.

You register a bill at the Where’s George? website by entering the denomination, series year, serial number, and your ZIP code. If you live outside of the United States, you can still participate by using the website’s list of global codes. Once you register a bill then…you spend it! If you want to increase the chance of having your bill being reported by someone, you can stamp the bill with information encouraging participants to visit the website and help track the bill’s journey.

Any person who receives your bill and decides to participate in tracking it enters the series year, serial number, and his or her local ZIP code on the Where’s George? website. This is known as a hit. Once a bill is registered, Where’s George? reports the time and distance traveled between hits, and any comments from the participants. Most bills do not receive any hits, but many bills receive two or more hits. Bills that are double- and triple-hitters are common, and some bills have 4 or 5 hits. After the participant enters the hit, then they, too, place the bill back into circulation by spending it.

Fans of the Where’s George? website often collect interesting patterns of hits such as getting at least one hit in all 50 states or getting hits on bills from all 12 Federal Reserve Banks. Fans can rank themselves for fun with their George Score. Your George Score is automatically calculated when you enter bills and get hits on Where’s George? The more bills you enter, and more importantly, the more hits you get, the higher your George Score. The George Score is a method of rating fans based on how many bills they have entered and also by how many total hits they have had. The formula is as follows:

100\times \left[{\sqrt  {\ln({{\rm {bills\ entered}}})}}+\ln({{\rm {hits}}}+1)\right]\times [1-({{\rm {days\ of\ inactivity}}}/100)]
However, since this formula is logarithmic it means that the more bills you enter and the more hits you receive, the less your score increases for each entered bill or new hit. Thus, your score does not increase as quickly when you enter a lot of bills. My George Score is 622.58 (for comparison, the top user has a George Score of over 1500). This makes my Where’s George? rank 6059 out of 16849. But my rank in my state is 277 out of 734.

Adventures In Time And Space 5: Cinder Lake Crater Fields

 Crater field #1 was designed to simulate Apollo 11 landing site taken from Lunar Orbiter images

Crater field #1 (above) was designed to simulate Apollo 11 landing site taken from Lunar Orbiter images (below)

The San Francisco Volcanic Field is located on the Colorado Plateau in northern Arizona. The major stratovolcano in the volcanic field is San Francisco Mountain. Cinder debris, black pea-sized frothy lava from these once-active volcanoes, covered the surrounding sedimentary rock surface during the Quaternary period.

In the 1960s, NASA wanted to train the astronauts in geology. The Astrogeology branch of the United States Geological Survey (USGS) in Flagstaff chose northern Arizona because its geological formations were thought to be similar to those on the moon. The Cinder Lake crater field was specifically chosen for the creation of a realistic lunar-like landscape.

In 1967, NASA completed the first phase of its lunar analog crater field with a 500 square-foot area designed to duplicate a section of Mare Tranquillitatis, a potential Apollo 11 lunar landing site that was captured in images from Lunar Orbiter II. The Cinder Lake field initially contained 47 craters with diameters of 5 to 40 feet. It was expanded later that year to an 800 square-foot field with 143 craters total. Over 300 pounds of dynamite and over 13,000 pounds of ammonium nitrate were used to blast the craters from the black lightweight cinder debris.

Cinder Lake Crater Field #1 was used to help train astronauts on identifying craters and on determining their location in a lunar landscape. The astronauts also practiced using geologic hand tools and testing scientific experiment packages and various lunar vehicle prototypes. A simulated Apollo lunar module ascent stage was also constructed and placed on a ramp to give it the appropriate height off the lunar analog surface.

In the second phase, NASA decided to build a larger 1,200 square-foot test field with 354 craters just north of Cinder Lake Crater Field #1. The new location was selected because the dark basaltic cinder over there covered the lighter clay beds, so that blasting craters would create distinctive light-colored ejecta, including crater rays.

Crater field was used to create Apollo 11 EVA planning map

Crater field was used to create Apollo 11 EVA planning map (simulated LM on ramp center left)

Final crater field contained 143 craters (simulated Lunar Module on ramp)

Final crater field contained 143 craters (simulated Lunar Module on ramp)

 Crater field #1 was used also to test Explorer vehicle prototype

Crater field #1 was used also to test Explorer vehicle prototype

The Pencil: History Of Design And Circumstance

Henry Petroski, the Aleksandar S. Vesic Professor of Civil Engineering and a professor of history at Duke University, traces the origins of the pencil by starting with the writing technologies of ancient Greece and Rome, continuing in the 1500s with the discovery of the mineral graphite, and goes through the Industrial Revolution with the development of mass production. He discusses how Henry David Thoreau worked in his father’s pencil factory, inventing techniques for grinding graphite powder and blending different mixtures of graphite, clay, and other substances to produce pencils with varying qualities of darkness and hardness. Petroski shares with us what the common pencil can teach us about design, engineering, and technology.

What Is A Number 2 Pencil?

Why do they always insist on you using a number 2 pencil?


Most modern pencils have a core made of a mixture of graphite and clay. The word pencil comes from the Latin word penicillus, meaning a little tail. In the 1500s, it was called plumbago, Latin for lead ore, because it was thought to be a form of lead. Consequently, the pencil core is still referred to as pencil lead, even though it never contained the element lead. Ironically, until about a half century ago, lead poisoning from pencils was possible due to the use of lead paint for the outer coat. This paint then could be ingested when the pencil was bitten or chewed.

Graphite is a mineral that is an allotrope of carbon (on the right, below). Allotropes are pure forms of an element that differ in structure. Graphite is carbon laid out in slippery sheets. Diamond (on the left, below) is carbon bonded into a rigid structure. Graphite was named in 1789 by Abraham Werner from the Greek word grapho, meaning to draw or to write. Unlike diamond, graphite is a conductor of electricity. Because of this property, it is useful as electrodes in arc lamps and batteries.

allotropes carbon

The development of the modern pencil started in the 16th century, when a large deposit of graphite was discovered in England that was very pure and solid enough to be cut into sticks and used for marking sheep. But because graphite is soft, the graphite sticks were wrapped in sheepskin or string for neatness and to prevent them from breaking apart. Shortly afterward, an Italian couple named Bernacotti, in an effort to improve the overall design, had started hollowing out sticks of wood and inserting graphite sticks into them. In 1795, Nicholas Conté discovered a procedure of mixing powdered graphite with clay to form rods that were then baked in a kiln. Conté discovered that by changing the ratio of graphite to clay, he could change the hardness of the pencil rod. The greater the amount of graphite, the softer the rod and the darker the pencil mark as it deposits more graphite onto the paper. The greater the clay, the harder the rod, the lighter the mark.

Conté created a numbering system for grading pencil hardness. He started at 1 and higher numbers indicated softer rods. Incidentally, this procedure of mixing graphite and clay was developed independently in the US in the 1800s by the father of Henry Thoreau, John Thoreau. His grading system, however, used higher numbers to designate, instead, harder rods. This 1-4 numbering system by Thoreau is still used in the US today. For the rest of the world, most of the pencils are graded on the European HB system developed in the early 20th century by Brookman, an English pencil maker. It allows for a greater selection of graphite-to-clay ratios by using a continuum from H (for hardness, or increasing clay) to B (for blackness, or increasing graphite).

pencil grades

If we translate the Thoreau numbering system to the European HB system, it is as follows:

1 = B          2 = HB          2.5 = F          3 = H          4 = 2H

The grade HB is at the middle of this continuum, offering a balance between erasability (graphite) and durability (clay). You want a pencil mark to be reasonably easy to erase without ripping a hole in the paper, but not so soft and dark that it smudges all over. Consequently, the standard writing pencil is graded HB… or… wait for it… number 2.