As of 2018, amino acids, which are the building blocks of protein, are legal in sports and not on the World Anti-Doping Agency (WADA) list of prohibited substances. Athletes frequently use amino acid supplements to aid in recovery, muscle repair, and growth as they are considered a nutritional supplement rather than a performance-enhancing drug. However, athletes need to be cautious about the purity of the supplements they consume. Some products may be contaminated with substances that are on the prohibited list, leading to unintentional doping violations. It's essential for athletes to choose high-quality, reputable brands and, when possible, products that are certified by third-party testing organizations to ensure they are free of banned substances.

To erase ink from a title, such as a book cover or a document, the method you choose depends on the type of ink and the material of the title. For non-permanent inks, applying a small amount of rubbing alcohol with a cotton swab gently over the ink can work wonders; it dissolves ink without damaging many surfaces. Another approach is to use a special ink eraser, available at stationery stores, designed specifically for removing ink without tearing the paper. For glossy or delicate surfaces, using an adhesive tape could lift off the ink. Press the tape onto the inked area and peel off carefully. In situations where the title is printed on paper, light abrasion with an art gum eraser might work, but this should be done gently to avoid damaging the material. Always test these methods on a small, inconspicuous area first to ensure they do not cause damage. It's crucial to proceed with caution and consider the material's resilience to chemicals or abrasion.

When working with PVC threads, achieving the correct tightness is crucial to prevent leaks while avoiding damage to the threads. PVC threads should be tightened by hand plus a quarter to a half turn with a wrench for the best seal. Using Teflon tape (PTFE) or pipe dope specifically designed for plastic threads can enhance the seal and make it easier to achieve the proper tightness. It's important not to overtighten, as doing so can strip the threads or crack the fitting due to PVC's relatively low tolerance for stress compared to metal. A good practice is to hand-tighten until snug, then use a wrench for the final adjustment, monitoring the connection for leaks. If a leak is detected, disassemble, reapply thread tape or dope, and reconnect. Remember, the integrity of the PVC fitting relies on maintaining the structural integrity of the threads, so proceed with caution and monitor for signs of stress.