A bundle of yarn is commonly referred to as a skein. A skein is how yarn is typically sold, characterized by its elongated, loosely-coiled shape. This configuration allows for the easy unwinding of yarn for knitting, crocheting, or weaving projects. Alternatively, yarn can also be wound into balls, hanks, or cakes, each differing slightly in preparation and use. Hanks are yarn loosely wound into a large ring and then twisted on itself, requiring winding before use. Cakes and balls present yarn in a more ready-to-use form, with the center-pull feature in cakes being particularly popular for its convenience. The term and choice of yarn arrangement can depend on the material, brand, and intended use, impacting ease of use and project planning.

In the context of chromatography, black ink can be separated into its constituent colors, revealing a complex mix of pigments used in the ink's formulation. Chromatography is a laboratory technique used to separate mixtures based on the differential distribution of each component between two phases – a stationary phase and a mobile phase. When black ink is subjected to chromatography, the ink is typically placed on a strip of filter paper (the stationary phase) and a solvent (the mobile phase) is allowed to travel up the paper, carrying the ink components with it. Different pigments move at different rates due to variations in their solubility and adsorption properties. As a result, black ink chromatography usually reveals a spectrum of colors, typically including shades of blue, green, yellow, red, and sometimes even orange and brown. The exact colors and their intensity depend on the specific type of black ink being analyzed. For instance, inks made from carbon black may show fewer colors than those containing dyes. This technique is not only useful for scientific purposes but also has applications in forensic science, art restoration, and quality control in the printing industry.

To memorize amino acids for the MCAT, start by categorizing them into groups: nonpolar, polar, acidic, and basic. Create mnemonic devices to remember each category, such as "Santa's Team Crafts New Quilts" for serine, threonine, cysteine, asparagine, and glutamine (polar amino acids). Use flashcards, drawing each amino acid structure repeatedly can reinforce memory through visual learning. Incorporating spaced repetition software like Anki can ensure you're reviewing the amino acids regularly without overwhelming yourself. Also, connecting each amino acid to a function or characteristic (e.g., glycine is small and fits into tight spots) can help anchor them in your memory. Lastly, practice by writing them out and quizzing yourself in different orders, not just alphabetically.