Wednesday, April 24, 2013

Nanoparticles: Engineering at the Molecular Level

A nanometer (nm) is one billionth of a meter or one thousandth of a micron. The scale in the picture ranges from 0.1 nm (atoms), to 1-100 nm (molecules), to 1000 nm (bacteria and cells). 1000 nm equals 1 micron (1 um). A glucose molecule has a diameter of 1 nm, and a hemoglobin molecule has a diameter of 6 nm. Breathing, eating, and other physiological functions depend upon the interactions of biomolecules, that is, nanoparticles. All cellular biochemistry takes place on the nanometer scale.

The human body has been dealing with nanoparticles (NP) since the beginning. Many ultrafine particles such as fine sand, smoke, diesel fumes, furnace emissions, and welding fumes have diameters in nanometers; these are natural or man-made nanoparticles.

So, why the concern about the safety of engineered nanoparticles? These particles are synthesized intentionally, and generally have a size of between 1 and 100 nm. Compared to larger particles, NP have increased surface area and unique properties such as conductivity, strength, and chemical reactivity. Dust explosions are a potential hazard. According to the IRSST in Quebec, Canada, the engineered nanoparticles of most concern are the long, thin carbon nanotubes and NP that do not dissolve in solution. ". . . the majority of the means of exposure control for ultrafine particles should be effective against NP and much research is currently being carried out to confirm this." There is less concern with older technologies such as microelectronics where "risks are adequately controlled." Now is the time for prevention, "since prevention and monitoring can be carried out at the design and implementation stages of a number of processes."

Saturday, April 6, 2013

Sketch the Map and Then Continuously Improve It

The science of improvement is to ask the fundamental questions shown in the diagram and then to iterate through the Plan-Do-Study-Act cycle. [Institute for Healthcare Improvement] Iteration is defined by Merriam-Webster as "a procedure in which repetition of a sequence of operations yields results successively closer to a desired result." This is not a randomized clinical trial, but it is the scientific method. As Donald Berwick put it, "Did you learn Spanish by conducting experiments? Did you master your bicycle or your skis using randomized trials? . . . Broadly framed, much of human learning relies wisely on effective approaches to problem solving, learning, growth, and development that are different from the types of formal science so well explicated and defended by the scions of evidence-based medicine." [Broadening the view of evidence-based medicine]

The process of improving Haz-Map has gone on for over 20 years. First it was a hobby, and in 2007, it became a full-time job. I took a two-year sabbatical in 1994-96 to work on Haz-Map while completing a fellowship in Occupational Medicine at the University of Washington. When I first started adding data to Microsoft Access from the NIOSH Pocket Guide in 1993, I found a book that helped me to answer the first question in the diagram:

"Intelligent databases are databases that manage information in a natural way, making information easy to store, access and use."
"Early maps only showed a few well-known features like the "Pillars of Hercules" (the modern Straits of Gibraltar) or the island of Sicily. Once the map was outlined in terms of its major features, succeeding generations of mapmakers filled in the details, and the coast-lines, mountains and river systems slowly became more precisely defined. Similarly, the concentric designer begins by sketching out the main features, based on the key constraints, and then successively elaborates these until the details are crystallized." [Parsaye & Chignell. Intelligent Database Tools and Applications. 1993]