Biomaterials that are implanted into the body are commonly altered in some capacity to increase biocompatibility, decrease local cellular toxicity, make them more customized to the patient, or to even offer some physiological impact to make the implant slightly better (10 pts). a) A common example of coating a biomaterial with a substance to make it perform better is coating metal stents for arteries with heparin, an anticoagulant. Explain at least two examples of biomaterials in which the main material is coated/treated/altered to perform better, and why that alteration is needed. Reference a source if needed. (4 pts). b) Modular designs are becoming increasingly popular in orthopedics. Provide two benefits of modular devices. Conversely state one of the predominant issues (6 pts).