Temperature medical applications

If the homopolymer decomposes at the fabrication temperature another approach is to make a copolymer that can be melt processed at a lower temperature. For example, polyhydroxybutyrate decomposes at the processing temperature (190°C), whereas the copolymer with valeric acid can be processed at 160°C without decomposition. These aliphatic polyesters are biodegradable and most importantly, the decomposition products are not toxic, hence their use in medical applications (e.g., sutures). 

Fish collagen fibrillar gels have not been studied, with the exception of shark collagen (Nomura et al., 2000a,b), probably due to their low denaturation temperature (Tt]), which renders these materials difficult to handle. The Tt] of shark collagen solution is approximately 30°C (Nomura et al., 1995), which results in the dissolution of the fibrillar gel of this collagen at 37°C (Nomura et al., 2000a). This indicates that the gel could not be practically used at the actual physical temperature of human medical application. The Tt] of chum salmon is approximately 19 °C (Kimura et al., 1988 Matsui et al., 1991), which is the main reason to be unstable at the actual physical temperature of human body. As the... 

Medical applications of biodegradable shape memory polymers include their use for removing blood clots formed during strokes. Preshaped foams can be used to fill cranial aneurisms. Loosely tied sutures made from fibers that have been stretched at 50 °C will tighten when heated just above room temperature. 

In most of the above-mentioned processes, high operation temperatures are necessary while the reaction atmospheres usually contain considerable amounts of steam because water is one of the reactants, or because water is added to reduce coke formation. Also in food processing and medical applications, steam is often used for sterilisation. Thus, in many applications the membranes must be sufficiently stable in environments of both increased temperature and containing steam. In this work, this is called hydrothermal stability. 

Although boron carbonyls are only stable at very low temperature, H3BCO reacts with hydroxide to give [H3BC02 2. which is stable at room temperature and is normally isolated as the mono sodium salt, Na[H3BC02H] [212], It was patented as a source of CO source for preparation of transition metal carbonyl complexes [213]. It is also a good source of CO for medical applications [214], It readily releases CO at physiological pH. 

There are several applications of ZnO that are due to its excellent piezoelectric properties [28,164]. Examples are surface-acoustic wave (SAW) devices and piezoelectric sensors [28,165-167]. Typically, SAW devices are used as band pass filters in the tele-communications industry, primarily in mobile phones and base stations. Emerging field for SAW devices are sensors in automotive applications (torque and pressure sensors), medical applications (chemical sensors), and other industrial applications (vapor, humidity, temperature, and mass sensors). Advantages of acoustic wave sensors are low costs, ruggedness, and a high sensitivity. Some sensors can even be interrogated wirelessly, i.e., such sensors do not require a power source. 

Choosing an adhesive for a medical application follows the same process as choosing an adhesive for any other purpose. Criteria include the particular substrates to be joined, strength requirements, type of loading, impact resistance, temperature resistance, fluid resistance, and processing requirements. However, the function of many medical devices requires at least two other important criteria resistance to sterilization and low toxicity. As a result, several important standards and regulations have been developed in the industry. 

Both room temperature and heat-curable epoxy adhesives are used in medical applications. The room temperature curing systems require metering and mixing, and the cure time is generally slow (several hours). Elevated-temperature cures could affect temperature-sensitive substrates. 

Note Polymers formed from compositionshaving Tg s lower than body temperature (37°C) are particularly preferred for medical applications. 

Fiber characteristics that should be taken into account for making filters include temperature capability, corrosion resistance (withstand adds, alkalies, solvents, etc.), hydrolysis (humidity levels), dimensional stability, and cost. Among important medical application of fibers, we should mention sutures and filters. Sutures are used to close the wound during surgical operations. Fibers used as sutures can be absorbable or nonabsorbable. The main requirements are that the suture must have only a minimal amount of reaction with the tissue and, in the case of absorption, there must be minimal chemical irritation (Lyman,... 

---