Сборник текстов на казахском, русском, английском языках для формирования навыков по видам речевой деятельности обучающихся уровней среднего образования
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- New materials and technologies on service of the person Dependence on properties of substances: their composition and structure
- Biological materials and biomaterial
- Development of drugs
| Environment protection
Some hundreds of years ago people lived in harmony with nature, because industry was not much developed. Today, however, the contradictions between man and nature are dramatic. The twenty first century is a century of the scientific and technological progress. The achievements of the mankind in mechanization and automation of industrial processes, in chemical industry and conquering outer space, in the creation of atomic power stations and ships are amazing. But at the same time, this progress gave birth to a very serious problem – the problem of environment. Ecology and the contamination of environment, is concerned with climate, over-population in certain areas, deaths of plant and animals, chemical contamination of seas, lakes and rivers as well as atomic experiments and dumping of atomic waste from power stations. Floods, unexpected draughts, and the greenhouse effect are the next reasons. There are many consequences of damaging the environment. One of them is acid rain. Another one is water shortage resulting from abuse of arable lands in agriculture. The third one is destroying the ozone layer of the Earth through pollution from factories and plants. The fourth problem is damage o water and soils. The fifth one is damage to wildlife: numerous species of animals and plants can disappear. At last, the most serious danger arising from damaging the environment is the result of the abovementioned consequences. This is the danger for the life and health of the man. The protection of natural resources and wildlife is becoming a political programme in every country. Numerous anti-pollution acts passed in different countries led to considerable improvements in environment. In many countries purifying systems for treatment of industrial waters have been installed, measures have been taken to protect rivers and seas from oil waters. But the environmental problems have grown beyond the concern of a single country. Their solution requires the co-operation of all nations.
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maintain living functions and to renew structural material. Thus, consideration of biological properties is a natural extension of physical and chemical properties. To a large extend, biological functions of any materials are related to their chemical and physical properties. However, reactions in biological systems are catalyzed by enzymes. Furthermore, products of one reaction may be reactants for another in a complicate scheme of reactions to maintain live. Malfunction of a reaction causes trouble, leading to disease or death. Thus, biological properties deserve special consideration. Biological materials and biomaterial Plasma, membrane, tissue, protein, lipid, enzyme, the digestive system, and the central nervous systems are some examples of biological materials, for which properties for consideration include growth and decay, turn over time, biological half life, retention time, composition and its change, and active ingredient. These are manifestation of physical and chemical properties of biological materials. However, biological properties allow us to identify and solve the biological problems. Biological materials had been studied by biologists, chemists, and engineers from the macroscopic, molecular, and functional view points. The chemistry of living is complex, and properties of biological materials towards biomaterials are of great interest. The general reaction of biological materials towards foreign biomaterials is expel (or rejection). Living tissues form a thin layer around the inert biomaterial, but materials that irritate the tissues causes inflammation. Most pure metals evoke severe tissue reaction due to their redox reactions. However, aluminum and titanium are metals of choice, because the formation of a thin oxide layer on their surface made them inert. Similarly, ceramics are compatible to body fluid because they are made of the metal oxides. The nature of the surface also affects the biological properties, rough ones enable tight attachment of tissues. Biological activities of materials can be divided according to biological functions. Substances that provide nutrition, energy, and structural need are called food, whereas those that disrupt the normal functions are called toxins. Substances used to correct the abnormal biological functions are called medicines. Polymers The term "polymer" derives from the ancient Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "parts"), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. Most polymers have the form of long, flexible chains. Having found out that, chemists began synthesizing artificial polymers. This has led to the establishment of industries producing synthetic fibres and numerous polymeric materials, many of which were less expensive and superior in various ways to the natural materials. Life depends fundamentally on organic polymers. These polymers provide not 588
only food but also clothing, shelter and transportation. Indeed nearly all the material needs of man could be supplied by natural organic products. The list of these materials and things made of them might br very long: wood, fur, leather, wool, cotton, silk, rubber, oils, paper, paints and so on. The organic polymers from which such things could be made include proteins, cellulose, starch, resins, and a few other classes of compounds. Because of the complexity and fragility of their molecules, the natural organic polymers, although known and used for ages. Synthetic polymers now available already possess several of the properties required in a structural material. They are light in weight, easily transported, easily repaired, highly resistant to corrosion and solvents, and satisfactory resistant to moisture. It would be necessary to add that they have long-lived durability and resistance to high temperatures One could list the principal products: such as fibres, synthetic rubbers, coatings, adhesives and a lot of materials called “plastics”. Plastics and synthetic coating are already in common use. It is desirable that they should be used on a large scale, and get further development. Development of drugs Drug development is the process of bringing a new pharmaceutical drug to the market once a lead compound has been identified through the process of drug discovery. It includes pre-clinical research on microorganisms and animals, filing for regulatory status, such as via the United States Food and Drug Administration for aninvestigational new drug to initiate clinical trials on humans, and may include the step of obtaining regulatory approval with a new drug application to market the drug. 
Timeline showing the various drug approval tracks and research phases Pre-clinical New chemical entities (NCEs, also known as new molecular entities or NMEs) are compounds that emerge from the process of drug discovery. These have promising activity against a particular biological target that is important in disease. However, little is known about the safety, toxicity, pharmacokinetics, and metabolism of this NCE in humans. It is the function of drug development to assess all of these parameters prior to human clinical trials. A further major objective of drug development is to recommend the dose and schedule for the first use in a human clinical trial ("first-in-man" [FIM] or First Human Dose [FHD]). In addition, drug development must establish the physicochemical properties of 589
the NCE: its chemical makeup, stability, and solubility. Manufacturers must optimize the process they use to make the chemical so they can scale up from a medicinal chemist producing milligrams, to manufacturing on the kilogram and ton scale. They further examine the product for suitability to package as capsules, tablets, aerosol, intramuscular inject able, subcutaneous inject able, or intravenous formulations. Together, these processes are known in preclinical development as chemistry, manufacturing, and control (CMC). Many aspects of drug development focus on satisfying the regulatory requirements of drug licensing authorities. These generally constitute a number of tests designed to determine the major toxicities of a novel compound prior to first use in humans. It is a legal requirement that an assessment of major organ toxicity be performed (effects on the heart and lungs, brain, kidney, liver and digestive system), as well as effects on other parts of the body that might be affected by the drug (e.g., the skin if the new drug is to be delivered through the skin). Increasingly, these tests are made using in vitro methods (e.g., with isolated cells), but many tests can only be made by using experimental animals to demonstrate the complex interplay of metabolism and drug exposure on toxicity. The information is gathered from this pre-clinical testing, as well as information on CMC, and submitted to regulatory authorities (in the US, to the FDA), as an Investigational New Drug application or IND. жүктеу/скачать 18,66 Mb. Достарыңызбен бөлісу:
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