Archives of Ask A Scientist!
About "Ask A Scientist!"
On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.
Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.
What is happening at the molecular scale to give rise to the unusual properties of a hydrogel? Gelatin comes from the protein collagen, the main protein in connective tissues such as bones and tendons. When the gelatin is dissolved in hot water, the long polymer chains can move freely in solution. As the solution cools, the motion of the chains also slows down, allowing some chains to encounter each other and become entangled. As the degree of entanglement increases, the liquid is trapped and immobilized. The result is a material that behaves somewhat like a solid and somewhat like a liquid. In the case of the chicken stock, as the carcass is boiled, collagen protein chains are leached out of the skin and bones. Gelation is sometimes reversible, as in the case of Jell-OŽ and chicken soup, which means that as the temperature rises, the chains disentangle and the gel melts.
In addition to gelatin, there are a number of other natural and synthetic polymers that can form gels. For example, there are several vegetarian, edible hydrogels that are made from agar, alginate, and carrageen, which are all polysaccharides (polymers chains made from sugars) that are extracted from seaweeds. Many cutting-edge chefs incorporate gels into their dishes by taking advantage of the science of gels to create unique tastes and textures. For example, by choosing a gel with a melting point near that of body temperature, they make small capsules that melt in the mouth, releasing flavor. For more information on gelatin and other food-related hydrogels, I recommend the book "On Food and Cooking" by Harold McGee.
- Are cats and dogs colorblind? Do cats' eyes glow in the dark?
- What about the atomic structure of a substance determines its color and/or luster?
- Why are dipole-dipole and London-Dispersion Forces so much weaker than hydron bonds? Why are intermolecular forces weaker than atomic bonds?
- How do airplanes fly?
- What is fiber optic cable and what advantages does it have over other technologies?
- Does gravity get stronger nearer to the ground? If so by how much?
- Can only water evaporate or can other liquids?
- Why, when you breathe in helium, does your voice change?
- How are radioisotopes used to battle cancer cells?
- Is it possible to use electrolysis or another method to separate NaCl into sodium and free floating chlorine gas?