Development of new diagnostic procedures and treatments for disease only occurs in the presence of an incentive. The patent system preserves the right of inventors to profit from their discoveries and is an important component of technological progress. However, a patent does not ensure that a new drug or medical device is effective and does not protect consumers who are not equipped to evaluate the benefits of new healthcare-related products.
For that reason, government agencies such as the Food and Drug Administration FDA in the USA are placed in charge of evaluating the effectiveness and safety of new biomedical technologies. It will be much easier to follow the discussion in later chapters on the subjects of implants and other biomedical technologies if an appreciation of certain anatomic and physiologic characteristics of the human body has been obtained.
In this chapter, we will describe and discuss the building blocks of the human body, and certain diseases such as arthritis which affect the structure and performance of the body. You should be better able to understand why implants are designed in certain ways so that they can be used to rehabilitate normal function. It is not always immediately appreciated that the human body and whatever devices are used to treat its diseases are made from materials.
Biotechnology – key technology of the 21st century
Discussion of anatomy and physiology and materials properties has set the stage for an exploration of the ways materials are used to construct biomedical devices. Most of us have family members who have had at least a brush with heart disease. In this chapter, we will discuss the anatomy of the heart and how this remarkable organ works.
Many technological advances have been made in the treatment of heart disease, though the ultimate goal remains development of a fully implantable artificial heart. In this way, drugs may act much more efficiently. In the last few chapters, we have discussed the state-of-the-art treatments for resolving missing or diseased tissues and organs.
For the most part, synthetic or processed natural materials are used to design implants, etc. Over the past two decades or so, scientists and engineers have begun to create tissues and organs in the laboratory, with the aim of eventually using those constructs for treatment of disease. Although simple tissues like skin substitutes are already available, more complex tissues and organs are still under development.
Biologists once could only study plants and animals at a macroscopic level, whatever was visible with the naked eye. The development of optical microscopes made it possible to discover and view cells, the fundamental building blocks of living tissue. When microscopes became even more powerful, it became evident that cells were highly complex structures containing components having discrete functions.
History of technology - The 20th century | temyrasi.tk
And yet, in the past few years, several communities are discontinuing water fluoridation, with some politicians arguing that the introduction of fluoride should be a personal and individual decision, not one made by government . A walk around any shopping mall will provide encounters with folks who are actively using rehabilitation aids. Their needs may have arisen as the result of war injuries and amputations or hereditary conditions.
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However, a noticeable proportion of those in wheelchairs are diabetes patients, the obese, or those suffering from emphysema. Admittedly, this adaptation had not proceeded very far by , although the first jet-powered aircraft were in service by the end of the war. But the construction of a satisfactory gas-turbine engine was delayed for a decade by the lack of resources, and particularly by the need to develop new metal alloys that could withstand the high temperatures generated in the engine.
This problem was solved by the development of a nickel-chromium alloy, and, with the gradual solution of the other problems, work went on in both Germany and Britain to seize a military advantage by applying the jet engine to combat aircraft. The principle of the gas turbine is that of compressing and burning air and fuel in a combustion chamber and using the exhaust jet from this process to provide the reaction that propels the engine forward.
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In its turbopropeller form, which developed only after World War II , the exhaust drives a shaft carrying a normal airscrew propeller. Compression is achieved in a gas-turbine engine by admitting air through a turbine rotor. In the so-called ramjet engine, intended to operate at high speeds, the momentum of the engine through the air achieves adequate compression.
The gas turbine has been the subject of experiments in road, rail, and marine transport, but for all purposes except that of air transport its advantages have not so far been such as to make it a viable rival to traditional reciprocating engines. As far as fuel is concerned, the gas turbine burns mainly the middle fractions kerosene, or paraffin of refined oil, but the general tendency of its widespread application was to increase still further the dependence of the industrialized nations on the producers of crude oil , which became a raw material of immense economic value and international political significance.
The 20th century
The refining of this material itself underwent important technological development. Until the 20th century it consisted of a fairly simple batch process whereby oil was heated until it vaporized, when the various fractions were distilled separately. Apart from improvements in the design of the stills and the introduction of continuous-flow production, the first big advance came in with the introduction of thermal cracking.
This process took the less volatile fractions after distillation and subjected them to heat under pressure, thus cracking the heavy molecules into lighter molecules and so increasing the yield of the most valuable fuel, petrol or gasoline. The discovery of this ability to tailor the products of crude oil to suit the market marks the true beginning of the petrochemical industry.
It received a further boost in , with the introduction of catalytic cracking. By the use of various catalysts in the process, means were devised for still further manipulating the molecules of the hydrocarbon raw material. The development of modern plastics followed directly on this see below Plastics. So efficient had the processes of utilization become that by the end of World War II the petrochemical industry had virtually eliminated all waste materials.
All the principles of generating electricity had been worked out in the 19th century, but by its end these had only just begun to produce electricity on a large scale. The 20th century witnessed a colossal expansion of electrical power generation and distribution.
The general pattern has been toward ever-larger units of production, using steam from coal- or oil-fired boilers. Economies of scale and the greater physical efficiency achieved as higher steam temperatures and pressures were attained both reinforced this tendency. As the market for electricity increased, so did the distance over which it was transmitted, and the efficiency of transmission required higher and higher voltages. The small direct-current generators of early urban power systems were abandoned in favour of alternating-current systems, which could be adapted more readily to high voltages.
Transmission over a line of miles km was established in California in at , volts, and Hoover Dam in the s used a line of miles km at , volts. The latter case may serve as a reminder that hydroelectric power , using a fall of water to drive water turbines, was developed to generate electricity where the climate and topography make it possible to combine production with convenient transmission to a market.
Remarkable levels of efficiency were achieved in modern plants. One important consequence of the ever-expanding consumption of electricity in the industrialized countries has been the linking of local systems to provide vast power grids, or pools, within which power can be shifted easily to meet changing local needs for current.
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