Liquid Drop Microscope

Using a transparent liquid as a lens, a laser beam can be used to project the contents of the liquid on a screen with significant magnification. This is a reworking of a design from Gorazd Planinsic (2001) which allows for changing projection angles and considerable flexibility for extremely low cost

Three Sister Crops: Understanding American Indian Agricultural Practices of Corn, Beans and Squash

American Indians have practiced an inter-planting system to produce corn, beans, and squash, for generations. These crops are known as the “Three Sisters”. In this lesson developed for secondary agriscience curriculum, students will understand the past, current and future production practices of the three important crops. Students will also apply their knowledge to understand the crop selection process and relate to the changing environment

Climate Change within a Biome

In this iLEARN lesson, students will investigate impacts of climate change on the native plants and animals, as well as the fisheries, agriculture, and forestry, within a biome of their choosing, and then develop and refine a solution for one of the impacts resulting from the climate change

Understanding Greenhouse Gases

Students will conduct hands-on experiments to see how greenhouse gases interact with the Earth’s atmosphere and how greenhouse gases affect temperature. This lesson introduces National Geographic’s Geo-Inquiry Process, where students will identify a Geo-inquiry question, collect data, and create a project around the answer to their question. Students will then present their findings to their peers and evaluate their Geo-Inquiry process

Avalanches on a conical bead pile: scaling with tuning parameters

Uniform spherical beads were used to explore the behavior of a granular system near its critical angle of repose on a conical bead pile. We found two tuning parameters that could take the system to a critical point where a simple power-law described the avalanche size distribution as predicted by self-organized criticality, which proposed that complex dynamical systems self-organize to a critical point without need for tuning. Our distributions were well described by a simple power-law with the power {\tau} = 1.5 when dropping beads slowly onto the apex of a bead pile from a small height. However, we could also move the system from the critical point using either of two tuning parameters: the height from which the beads fell onto the top of the pile or the region over which the beads struck the pile. As the drop height increased, the system did not reach the critical point yet the resulting distributions were independent of the bead mass, coefficient of friction, or coefficient of restitution. All our apex-dropping distributions for any type of bead (glass, stainless steel, zirconium) showed universality by scaling onto a common curve with {\tau} = 1.5 and {\sigma} = 1.0, where 1/{\sigma} is the power of the tuning parameter. From independent calculations using the moments of the distribution, we find values for {\tau} = 1.6 \pm 0.1 and {\sigma} = 0.91 \pm 0.15. When beads were dropped across the surface of the pile instead of solely on the apex, then the system also moved from the critical point and again the avalanche size distributions fell on a common curve when scaled similarly using the same values of {\tau} and {\sigma}. We also observed that an hcp structure on the base of the pile caused an emergent structure in the pile that had six faces with some fcc or hcp structure.Comment: 8 pages, 6 figures; submitted to Granular Matter; Reformatted into LaTeX from Word; Fixed typo in uncertainty of tau; Rearranged two paragraphs to improve flo

Sustainable Agriculture Lesson for Middle School Classrooms

In this lesson, students will learn about sustainability, where farmers/agriculturists can meet the needs of food, fiber, and fuel for the growing population. Students learn about growing population, its growth rate, major food source, sustainability barrel, potential ripple effects of positive impacts as well as the food waste and its effects

Recycling Aluminum

Students will investigate and compare the energy cost to produce aluminum products from aluminum ore and recycled aluminum. Students will perform an electrolysis activity to reinforce the idea that recycling metal requires less energy than mining and refining metals from their original source in the earth

Using a Case Study Approach to Teach Invasive Species and Climate Change

In this teaching module, students will explore emerald ash borer (EAB), its impacts on the ash trees, and how warming temperatures could affect EAB populations. The emerald ash borer is a green buprestid or jewel beetle native to north-eastern Asia that causes devastating disease in ash trees

Organometallic Pillarplexes That Bind DNA 4-Way Holliday Junctions and Forks

Holliday 4-way junctions are key to important biological DNA processes (insertion, recombination, and repair) and are dynamic structures that adopt either open or closed conformations, the open conformation being the biologically active form. Tetracationic metallo-supramolecular pillarplexes display aryl faces about a cylindrical core, an ideal structure to interact with open DNA junction cavities. Combining experimental studies and MD simulations, we show that an Au pillarplex can bind DNA 4-way (Holliday) junctions in their open form, a binding mode not accessed by synthetic agents before. Pillarplexes can bind 3-way junctions too, but their large size leads them to open up and expand that junction, disrupting the base pairing, which manifests in an increased hydrodynamic size and lower junction thermal stability. At high loading, they rearrange both 4-way and 3-way junctions into Y-shaped forks to increase the available junction-like binding sites. Isostructural Ag pillarplexes show similar DNA junction binding behavior but lower solution stability. This pillarplex binding contrasts with (but complements) that of metallo-supramolecular cylinders, which prefer 3-way junctions and can rearrange 4-way junctions into 3-way junction structures. The pillarplexes’ ability to bind open 4-way junctions creates exciting possibilities to modulate and switch such structures in biology, as well as in synthetic nucleic acid nanostructures. In human cells, the pillarplexes do reach the nucleus, with antiproliferative activity at levels similar to those of cisplatin. The findings provide a new roadmap for targeting higher-order junction structures using a metallo-supramolecular approach, as well as expanding the toolbox available to design bioactive junction binders into organometallic chemistry