A pencil-drawn chemiresistor can detect the presence of hazardous gases. “Now our students showed that this can be done simply with a pencil and paper — and it works,” Huang said. “This is a great ...

If the tree is a pin oak or red oak, multiply the diameter by 3.5. The result is the approximate age in years. We stress that this is an estimate – not an exact way of measuring a tree’s age.