Surfce culture 5 nd the submerged culture
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SECTION 6
Grammar: 1. Пассивный залог.
- Самостоятельный причастный оборот.
- Придаточные обстоятельственные предложения.
TEXT A. THE PRODUCTION OF PENICILLIN
The industrial manufacture of penicillin on a large scale is carried out in several stages of which the first is fermentation. This is the cultivation in vessels of a penicillin-producing fungus1 on a suitable medium in which penicillin accumulates. In the second stage penicillin is extracted from the culture medium,2 concentrated and purified. In the third stage the sterile concentrated solution of purified penicillin which has passed the necessary tests for potency and absence of pyrogenic or other toxic impurities3 is put into ampoules and dried by means of the freeze-drying process.4 Finally the ampoules are labelled and packed for distribution.
Fermentation. Two fermentation methods have been used for the production of penicillin, the "surface culture" 5 and the "submerged culture" method.6 The surface culture method was used exclusively at the beginning of the development of large-scale manufacture of penicillin. It being expensive and unproductive, the submerged culture process has gradually replaced it.
Submerged culture method. The principle of the submerged method is to grow the fungus in large steel containers in a medium which is constantly agitated and aerated.7 Under these conditions the fungus grows not only on the surface but throughout the medium.
The submerged method of penicillin production has several important advantages over the surface method, one of them being the economy of labour. Instead of thousands of small surface fermentation vessels8 each of which must be washed, filled, inoculated and emptied, only a small number of units9 is required for the submerged culture method which can be controlled much more easily.
Another advantage is economy of space, as in the surface method the culture medium can be used only in shallow layers,10 so that a very large» surface is required to obtain substantial quantities of culture fluid containing penicillin.
Lastly, higher yields of penicillin 11 are obtained and it is possible to prepare final products of a high degree of purity by a simpler procedure of purification.
Note
- penicillin-producing fungus — плесень, служащая материалом для производства пенициллина
- culture medium — питательная среда для разведения культуры пенициллина
- tests for potency and absence of pyrogenic or other toxic impurities — испытания на активность и отсутствие пирогенных и других токсических примесей
- by means of the freeze-drying process — при .помощи процесса сухого замораживания'
- the "surface culture" method — метод поверхностного брожения культуры пенициллина
- the "submerged culture" method — метод погруженной культуры или метод нижнего брожения
- in a medium which is constantly agitated and aerated — в среде, которая постоянно взбалтывается и газируется воздухом
- surface fermentation vessels — бродильные установки для получения пенициллина методом поверхностного брожения
- unit (зд. в значении vessel) — емкость, танкер
- shallow layers — поверхностные слои П. yield of penicillin — выход пенициллина
Exercises
I. Образуйте от следующих глаголов существительные, используя суффиксы -tion, -ment:
cultivate, produce, extract, concentrate, purify, inoculate, filtrate, contaminate, develop, require, measure
If. Переведите прилагательные с суффиксом -less, обозначающим отсутствие чего-либо.
home — дом, homeless — бездомный
colourless, stainless, careless, useless, airless, harmless, tasteless, hopeless, waterless, painless
- * Прочтите предложения; поставьте глагол, данный в скобках, в соответствующую форму.
1. The filter (to make, to be made) of paper, sand, ground and glass. 2. The investigator (to treat, to be treated) the mixture of solid fatty acid with an aqueous solution of a surface active agent. 3. The air (to supply, to be supplied) from compressors in insulated pipe lines. 4. The chemist (to use, to be used) various materials for spore production. 5. Sterilization of the medium (to do, to be donfc) by steam. 6. Two fermentation methods (to use, to have been used) for the production of penicillin. 7. The surface method (to replace, to have been replaced) gradually by the submerged one.
- Переведите предложения, содержащие самостоятельный причастный оборот, на русский язык.
The temperature reaching the boiling point, the heater was switched off. Так как температура достигла точки кипения, нагреватель был выключен.
- * Вставьте вместо пропусков соответствующие слова или словосочетания:
hence, it seems, therefore, as is known, it must be remembered, I should say.
1. ... small particles of the drug remained suspended in the liquid fatty phase. 2. ... that nitrogen not only does not combine with oxygen readily but it does not combine with any other element easily. 3. ... particle size and polymorphism influence drug absorption. 4. ... both preparations were excellently tolerated. 5. ... that the intravenous injection of autistine produces good results in cases of ventricular extrasystole. 6. ... that in this case bromide has to be administered as a sedative.
- Прочтите предложения, определите, вместо каких существительных употреблены that of и those of и переведите предложения на русский язык:
I 1. The effect of magnesium trisilicate on partition coefficient is more evident than that of aluminium. 2. The adsorption of mete- namic acid on aluminium hydroxide was found to be much higher than that of flutenamic acid. 3. The proportion of the soluble principles in the finest dust of the powder is larger than that of the insoluble substance. 4. The adsorption of acetylsalicylic acid on aluminium hydroxide is lower than that of salicylamide. 5. The colouration of the tested solution should not be more intensive than that of the standard solution.
- * Закончите предложения, использовав следующие слова:
pharmacy, a percolator, the cells, the drug, the menstruum, the mare, strengths
1. The drugs are macerated in definite quantities of .... 2. The menstruum consists , of alcohol of various .... 3. Percolation is- one of the most important methods of drug extraction employed in ... .4. The instrument used to hold the powder is called .... 5. The soluble principles of vegetable substances are generally contained in ... . 6. The process of maceration consists simply of extraction by soaking .... 7. The residual drug remaining in the percolator after the extraction of the soluble constituents is called ....
- Переведите на английский язык:
1. Процеживание (перколяция)—самый важный и полезный метод экстракции лекарств. 2. При процессе вымачивания лекарственное вещество погружается в растворитель. 3. Вещество помещается в бутылку с растворителем и плотно закрывается. 4. Полученное вещество время от времени взбалтывается в течение 2—14 дней.
- Ответьте на вопросы по тексту А.
1. What principle modes of drug extraction are used in pharmacy? 2. What is the most important and useful method of drug;
extraction? 3. What process is called maceration? 4. What are the drugs macerated in? 5. What does the menstruum consist of? 6. In what process is a granulated or powdered drug deprived of its constituents? 7. In what process do physical forces play an important part? 8. What instrument is called a percolator? 9. What proportion of the percolate is usually the most dense? 10. What would the process of percolation be if the soluble principles could be separated from the insoluble cellular substance and be deposited in the ground particle?
XIV. Прочтите текст. Ответьте на вопросы:
а) Сколько существует способов получения алкалоидов в чистом виде? б) Как поступают с примесями при экстракции алкалоидов? в) Для чего необходима дальнейшая сепарация и преципитация растворов, содержащих алкалоиды?
TEXT В. EXTRACTION OF ALKALOIDS
The alkaloids in alkaloid-containing drugs are in varied states of combination and it has been found that the therapeutic properties of galenicals are not always identical with those of the pure alkaloids or alkaloidal salts. Extracts of such drugs are usually prepared by maceration or percolation of the powdered drug with aqueous alcohol, of such strength that the alkaloids, their salts, and complexes are completely extracted. Unwanted substances such as gums, mucilages, starch, and protein are left behind. Tannins, colouring matters, small quantities of oily and resinous substances are usually extracted along with alkaloids.
When it is desired to obtain the alkaloids in a pure state, two general processes are available. Both of these are based on the fact that free alkaloidal bases are usually but sparingly soluble in water but are soluble in organic solvents.
Process A. The powdered drug is moistened with water and mixed with lime, which combines with acids, tannins and other phenolic substances and sets free the alkaloids. Extraction is then carried out with organic solvents such as benzene or petroleum spirit. The organic liquid is then shaken with aqueous acid and allowed to separate. Alkaloidal salts are now present in the aqueous layer, while oily and resinous substances remain in the organic solvent.
Process B. The powdered drug is extracted with water or aqueous alcohol containing dilute acid. Pigments and oily impurities are removed from the acid solution by shaking with chloroform or other organic solvent. The free alkaloids are then precipitated by the addition of excess of sodium bicarbonate or ammonia, and separated by filtration or by extraction with organic solvents.
In practice the above processes will usually give mixtures of several alkaloids, the separation of which is often necessary. This is done by fractional precipitation or by fractional crystallization 'of such salts as the oxalates, tartrates, or picrates.
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