Biodegradable polymer sutures Biodegradation: A biological agent (an enzyme, microbe or cell) responsible for degradation. Most degradable polymers are polyesters. Polymers prepared from glycolic acid and lactic acid have found a multitude of uses in the medical industry, beginning with the biodegradable sutures first approved in the 1960s. Since that time, diverse products based on lactic and glycolic acidand on other materials, including poly(dioxanone), poly(trimethylene carbonate) copolymers, and poly ( -caprolactone) homopolymers and copolymershave been accepted for use as medical devices. In addition to these approved devices, a great deal of research continues on polyanhydrides, polyorthoesters, polyphosphazenes, and other biodegradable polymers. Bio-absorbable polymers have been used for sutures, vascular clips, and fixation implants for both intra-articular fracture and malleolar fractures.
In the literature these implants are controversial. Potential benefits remain for the use of this material for interference screws if the problems of inflammation are minimal and the fixation properties are sufficient. There is no need for second operation for removal. Some examples of biodegradable materials includes: Segmented polyurethanes(SPU)-Highly porous, open celled foams. These compounds are used for smaller implants only they do not provide sufficient support for large segments of bone. Chitin-Naturally occuring material found in shellfish coral. Chitin is composed mainly of carbonate. The degradation of chitin results in water, carbonate ions, and carbone dioxide, non toxic compounds.
The Essay on The Information Age Is Upon Us The Raw Materials Are
The information age is upon us. The raw materials are ones and zeros. The technology used to transport the ones and zeros provides numerous opportunities for entrepreneurs, scientists, and engineers. Telecommunications is dynamically changing the way we work, learn, communicate, and view society. At no other time in history have so many people been given the ability to exchange ideas, sell their ...
Since the carbonic acid system is a major buffer of blood pH levels, these compounds are already common in the body and the byproducts can easily be broken down and excreted through respiration. The structure of chitin is very similar to bone, so it favors the reformation of healthy tissue. Unfortunately, chitin does not provide enough support for large segment of bone. Also compounds may have to be used to prevent coagulation and rejection by the body. Poly(L-Lactic Acid)-Fibers that have properties similar to ceramics. This is a naturally occurring compound that will degrade slowly over time. It provides good support, but concerns have arisen over the toxic effects of its degradation. Late inflammatory and bone resorption processes occur over time.
Also there are concerns about its acidic make up. As it breaks down, the acids could cause adverse effects in the surrounding tissues. Calcium Phosphate Ceramics-Are usually used as cements in adhering implants to existing bone structures. They do not provide adequate support for large segments, but can be used to lengthen existing bone by inserting segments. This material will degrade over time, allowing the separated bone fragments to rejoin at proper length. Hydroxyapatite(HA) is a member of this group. Because biodegradable polymers are hydrolytically unstable, the presence of moisture can degrade them in storage, during processing, and after device fabrication. In theory, the solution for hydrolysis instability is simple: eliminate the moisture and thus eliminate the degradation. However, because the materials are naturally hygroscopic, eliminating water and then keeping the polymer free of water are difficult to accomplish. The as-synthesized polymers have relatively low water contents, since any residual water in the monomer is used up in the polymerization reaction.
The polymers are quickly packaged after manufacturegenerally double-bagged under an inert atmosphere or vacuum. The bag material may be polymeric or foil, but it must be highly resistant to water permeability. To minimize the effects of any moisture present, the polymers are typically stored in a freezer. Packaged polymers should always be at room temperature when opened to minimize condensation, and should be handled as little as possible at ambient atmospheric conditions. As expected, there is a relationship among biodegradation rate, shelf stability, and polymer properties. For instance, the more hydrophilic glycolide polymers are much more sensitive to hydrolytic degradation than are polymers prepared from the more hydrophobic lactide. Final packaging consists of placing the suture or device in an airtight, moistureproof container.
The Essay on Water temperature effects on sugar
1. Introduction The purpose of my project is to demonstrate how water temperature affects the dissolving of sugar in liquid. Everything in our universe is made up of particles which are in constant motion. In a solid state particles move the slowest while in a liquid state particles move the fastest. Under the right conditions, solid particles (the solute) when mixed in liquid (the solvent) can ...
A desiccant can be added to further reduce the effects of moisture. Sutures, for example, are wrapped around a specially dried paper holder that acts as a desiccant. In some cases, the finished device may be stored at subambient temperature as an added precaution against degradation. Factors That Accelerate Polymer Degradation : more hydrophilic backbone; more hydrophilic endgroups; more reactive hydrolytic groups in the backbone; less crystallinity; more porosity; smaller device size. The lion’s share of the total medical biodegradables market in 1995, this is a mature area not expected to grow rapidly in the future. About 125 million synthetic bioabsorbable sutures are sold each year in the United States. They are divided into braided and monofilament categories. Braided sutures are typically more pliable than monofilament and exhibit better knot security when the same type of knot is used. Monofilament sutures are more wiry and may require a more secure knot.
Their major advantage is that they exhibit less tissue drag, a characteristic that is especially important for cardiovascular, ophthalmic, and neurological surgeries. A recent source in the literature lists eight objective and three subjective parameters for suture selection based on criteria such as tensile strength, strength retention, knot security, tissue drag, infection potential, and ease of tying. When the sutures warmed to body temperature, the threads contracted and closed the wound. Measurements of the force on the wound, suggested it was applying just the right amount of pressure. While sutures were the first commercial product and still account for the vast majority of all sales, a variety of products are now on the market for an expanding range of applications, with others certain to appear in the next decade..
The Business plan on The Knot
According to Sahlman, the success of entrepreneurial ventures, such as The Knot, is dependent on four critical success factors, namely the people, the opportunity, the deal and the context. Each of these factors is dynamic and the entrepreneur must constantly reevaluate and adjust the four factors to create value. People The category people include the key players of the entrepreneurial venture. ...
