I. Introduction
The problem given is to select the material for and design the next generation of coronary stents, which are used in the treatment of coronary heart disease. The final material must be commercially available, have published properties, be a solid cylinder, have a diameter of 8mm, a length of 15 mm, be biocompatible, and meet several engineering constraints.
To solve the given problem, the researcher first looked at various journals and scholarly publications to see what types of materials are generally used in coronary stents. From this group of materials, the final selection was narrowed down further by looking at specific material properties using the online Material Property Database online at www.matweb.com. From this data, the final three candidates were selected. Analyzing each material and looking at the cost and availability of these materials allowed the researcher to select one final material that met the given constraints. After all research was completed Nitinol, or Nickel Titanium, was selected as the best material for the next generation of coronary stents.
II. Analysis
Material Density Elastic Modulus Yield Strength Yield Strength % Commercial Availability Biocompatibility
316LVM Sandvik Bioline 8.00 g/cc 200 GPa 800 MPa 12% Alloy Wire International Yes Extremely Well
Nb-1Zr 8.59 g/cc 68.9 GPa 241 MPa not published Vegas Fastner
High-N Bar Steel 8.00 g/cc 200 GPa 1100 MPa 15% Sandvik Materials Technology
Nitinol 6.45 g/cc 28 GPa 850 MPa 15.50% Metalmen Sales Yes Extremely Well
Tantalum 16.65 g/cc 186 GPa 450 MPa not published MarkeTech International
X2CrNiMnMoN22136 Stainless Steel 7.76 g/cc 209 GPa 1050 MPa 35% Metal Suppliers Online Yes
Gold 19.32 g/cc 77.2 GPa 120 MPa...
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...h an oxide layer caused by dipping in nitric acid is resistant to interaction with the environment in which it is placed. All of the factors make Nitinol an excellent choice to make a stent out of.
V. Synthesis
Nitinol is a mixture of 50% Nickel and 50% Titanium. Once made it must go through several steps to set the shape and become biocompatible. In order for the Nitinol to get its shape memory characteristics, it must be heat-treated. Before the heat-treating starts, the wire is shaped into its desired form, and after the heat treatment, the metal becomes stronger and will “remember” the shape. Finally, the sample must be soaked in an acid to create the oxide layer, which prevents it from interacting with its environment. Nitinol is also easily machined, which with its shape memory, and oxide coating makes it a great choice for use in medical devices.
Transcatheter aortic valve replacement or TAVR is the latest technology used principally for the treatment of aortic stenosis, a condition in which one of the major valves of the heart, the aortic valve, becomes tight and stiff, usually as a result of aging (3). Since many patients who need aortic valve replacement for aortic stenosis are too sick to undergo major valve replacement surgery, they are unable to get the treatment they need. With the transcatheter aortic valve, this issue is bypassed because this valve can be implanted in the heart by accessing the patient’s heart through an artery in the groin. The valve can be inserted through a wire that can be pushed to the heart and the old valve is simply pushed to the side when the new valve is implanted. This technology has been in use in the US with Edwards’ Sapiens valve since 2011 and has saved the lives of many patients with aortic stenosis (4). Medtronic’s CoreValve uses similar technology and has won patent fights in Europe and has been in use internationally. However, within U.S., Medtronic has not been...
The purpose of conducting experiment was to determine the identity of white compound. Based on the 5 gram of unknown white compound several experiment conducted including solubility test, pH test, flame test, and ion test. Several materials including chemicals used throughout experiment and will be described through paragraphs.
Prof. Amanda Ellis: The problem with catheters is the ability to get bacterial attachment to the surface of the polymer. There are two approaches to this problem using nanotechnology: coating or copolymerization. The approach of the coating works when an antimicrobial layer is placed on top of the lens. The antimicrobial the Flinders Research team has been using is an extract from cloves. Dentists have also been using this compound to stop oral infections. The other approach is when the antimicrobial agent is combined with the polymer and this is called ‘copolymerization’. The reason why copolymerization is more effective is the coating can be abraded off. However with the copolymerization the antimicrobial is part of the compound and forms covalent bonds (share of electrons). It is important that the bonds are strong as the material could come out of the polymer and cause even more damage.
In today’s society, people are gaining medical knowledge at quite a fast pace. Treatments, cures, and vaccines for various diseases and disorders are being developed constantly, and yet, coronary disease remains the number one killer in the world.
The late sixties were a time filled with sex, drugs, and rock and roll. A huge part of American culture at the time was focused around these three things. Musicians possessed a tremendous amount of social influence, and like wise, society put a lot of emphasis on the lives and attitudes of musicians. Of the rock groups from this time period, the Beatles were by far the most influential. The British rock group was probably the most catalytic band in rock and roll history. Although they came together in the shadow of the Beatles, another band of that era was Jefferson Airplane. Jefferson Airplane was deemed the first of the San Francisco psychedelic rock groups. Jefferson Airplane was always considered to be a psychedelic rock group, but it was not until later in their existence that the Beatles fell into this category as well. Both groups earned this title for their creative style of rock as well as for their experimentation with drugs. Each of these groups wrote songs that alluded to drug use at one time or another. Two of the most criticized songs from these bands are Lucy in the Sky with Diamonds by the Beatles, and White Rabbit by Jefferson Airplane. White Rabbit is a song latent with drug references. The connection with drugs in Lucy in the Sky with Diamonds is not as clear. Although John Lennon claims that he had no intention of making references to LSD in his song, the abstract lyrics and metaphoric language invite drug connotation. Lucy in the Sky with Diamonds and White Rabbit mirror each other in their association with LSD and their allusions to Alice in Wonderland, but looking into these songs more deeply it is obvious that both artists were writing about escape; escaping reality.
... of the need of duplicate revascularization over balloon angioplasty [75]. Both pre- and post -conditioning appears to protect cardiomyocytes at the time of reperfusion therapy. Ischemic post-conditioning is a chain of repetitive intermissions of coronary blood flow administered after a period of ischemia. Inhibition of ONOO−-induced nitro-oxidative stress might pay a critical role in postcon-mediated cardioprotection [76]. Iliodromitis et al also reported that postcon-mediated cardioprotection was in cohorts with reduced nitro-oxidative stress in vivo. The acknowledgment that iNOS activation in cardiac myocytes could be advantageous and that nitriate/NO could have both beneficial and detrimental effects, lead to the dose of 1400W iNOS inhibitor being chosen to significantly inhibit, but not restrict, increase in the level of myocardial iNOS activity after MI [77]
These kinds of polymers have both some advantages and disadvantages. Although they are bioactive and biodegradable and provide high comppressive strength, Degradation of such polymers leads to undesired tissue response due to producing acid formation in degradation process. Metallic scaffolds are another method for bone repair and regenaration. They provide high compressive strength and enormous permanent strength. Metallic scaffolds are mainly made of titanium and talium metals. The main disadvantages of metallic scaffolds are not biodegradable and also discharge metal ions. Recent studies in metallic scaffolds mainly focus on biodegradable materials which can be used improve bioactivity of metals such as titanium.
Coronary heart disease came in the public eye in the mid-20th century as a disease of pandemic magnitudes and it continues to be a major cause of death in the western world. The fundamental cause of coronary heart disease is Atherosclerosis. The term “atherosclerosis” is the combination of two Greek words which correctly imply the elements of the lesion. The first being “athero” the greek work for gruel which parallels to the necrotic core at the base plaque formation, and “sclerosis” from the Greek word hardening, corresponding to the fibrous cap on the outer layer of the plaque. (Vulnerable Atherosclerotic Plaque : Strategies for Diagnosis and Management, 1, 2)
In United States, according to American Heart Association, Cardiovascular disease also called Heart Disease is number one cause of death in United States. There are different types of heart disease and one of them is Coronary Heart disease or Coronary Artery Disease/CAD. Coronary Artery disease or CAD is the most common type of heart disease for both men and women. It is unannounced and can be a silent killer. CAD is mostly can be from damaged or diseased arteries. Some conditions, habits, or traits may increase the risk of CAD and the more problem shows, th...
Denture teeth can be made of acrylic poly(methyl methacrylate) (PMMA) or composite resins. PMMA is a polymer - a material made the from joining of methyl methacrylate monomers. Properties of PMMA include resistance to abrasion, chemical stability and a high boiling point. (Jun Shen et al. 2011). However, weak flexure and impact strength of PMMA are of concern as they account for denture failure. (Bolayir G, Boztug A and Soygun K. 2013). Composite denture teeth are made of a three distinct phases - filler, matrix and coupling agents. Out of the types of composite teeth available, nano-filled composite teeth are preferred. Composite teeth have a PMMA coating around the tooth and a high content of filler particles. This gives them strength, higher resistance to forces than acrylic teeth and provides compete polymerization due to the PMMA coating. (Anusavice, K. J., Phillips, R. W., Shen, C., & Rawls, H. R, 2012). If the interface between the PMMA denture base and PMMA or composite teeth was weak, the denture will not be able to sustain occlusal forces, making the base-teeth interface, an entity of significance.
- The amount of times the mixture was stirred. We stirred the mixture until the Ammonium Nitrate was dissolved, so the amount of times we stirred after each teaspoon was different.
Another widely used primary cell is the zinc-mercuric-oxide cell, more commonly called a mercury battery. It can be made in the shape of a small flat disk and is used in this form in hearing aids, and electric wristwatches. The negative electrode consists of zinc, the positive electrode is of mercuric oxide, and the electrolyte is a solution of potassium hydroxide. The mercury battery produces about 1.34 volts.
Coronary artery disease (CAD) is the number one killer in America, affecting more than 13 million people. CAD occurs when a fatty substance called plaque builds up in the coronary arteries. These arteries disperse oxygen-ric...
NIMS is a uniform set of processes and procedures that emergency responders at all levels of government will use to conduct response operations. NIMS helps improve cooperation and interoperability among organizations. The framework is adaptable and accessible. It encourages all hazards preparedness. NIMS enables a variety of organizations to contribute successfully in emergency management and incident response. NIMS creates uniform professional emergency management and incident response practices.