2015-10-13
692
Ex. 60. Translate the following text into Ukrainian.
The quality of life emerges on the level of the cell. Just as an atom is the smallest unit of an element, so too the cell is the smallest unit of life. The difference between a living cell and a conglomeration of chemicals illustrates some of the emergent properties of life.
Fundamentally, all cells contain genes, units of heredity that provide the information needed to control the life of the cell; subcellular structures called organelles, these being miniature chemical factories that use the information in the genes and keep the cell alive; and a plasma membrane, a thin sheet surrounding the cell that both encloses a watery medium (the cytoplasm) that contains the organelles and separates the cell from the outside world. Some life-forms, mostly microscopic, consist of just one cell, but larger life-forms are composed of many cells whose functions are differentiated. In these multicellular life-forms, cells of similar type are combined into tissues, each performing a particular function. Various tissue types combine to make up a structural unit called an organ. Several organs that collectively perform a single function are called an organ system, and all the organ systems functioning cooperatively make up an individual living thing, the organism.
Ex. 61. Translate the following text into Ukrainian.
Organisms can be grouped into three major categories, called domains: (1) Bacteria, (2) Archaea [a:¢kı(:)ə], and (3) Eukarya [ju¢kærıə]. This classification is based on fundamental differences among the cell types that comprise these organisms. Members of both the Bacteria and the Archaea normally consist of single, simple cells. Members of the Eukarya have bodies composed of one or more highly complex cells and are subdivided into four kingdoms: Protista, Fungi [¢fΛndзı], Plantae, and Animalia. There are exceptions to any simple set of criteria used to characterize the domains and kingdoms, but three characteristics are particularly useful: cell type, the number of cells in each organism, and the mode of nutrition – that is, energy acquisition.
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Ex. 62. Translate the following text into Ukrainian.
There are two fundamentally different types of cells: (1) prokaryotic and (2) eukaryotic. Kariotic refers to the nucleus of a cell; eu means “true” in Greek; eukaryotic cells possess a “true”, membrane-enclosed nucleus. Eukaryotic cells are larger than prokaryotic cells and contain a variety of other organelles, many surrounded by membranes. Prokaryotic cells do not have a nucleus; their genetic material resides in their cytoplasm. They are small – only 1 or 2 micrometers long – and lack membrane-bound organelles. Pro means “before” in Greek; prokaryotic cells almost certainly evolved before eukaryotic cells (and eukaryotic cells probably evolved from prokaryotic cells). Bacteria and Archaea consist of prokaryotic cells; the cells of the four kingdoms of Eukarya are eukaryotic.
Ex. 63. Translate the following text into Ukrainian.
All organisms need energy to live. Photosynthetic organisms capture energy from sunlight and store it in molecules such as sugars and fats. These organisms, including plants, some bacteria, and some protists, are therefore called autotrophs, meaning “self-feeders”. Organisms that cannot photosynthesize must acquire energy prepackaged in the molecules of the bodies of other organisms; hence, these organisms are called heterotrophs, meaning “other-feeders”. Many archaeans, bacteria, and protists and all fungi and animals are heterotrophs. Heterotrophs differ in the size of the food they eat. Some, such as bacteria and fungi, absorb individual food molecules; others, including most animals, eat whole chunks of food and break them down to molecules in their digestive tracts (ingestion).
Ex. 64. Translate the following text into Ukrainian.
Monosaccharides, especially glucose and its relatives have a short life span in a cell. Most are either broken down to free their chemical energy for use in various cellular activities or are linked by dehydration synthesis to form disaccharides or polysaccharides. Disaccharides are often used for short-term energy storage, especially in plants. Common disaccharides include sucrose (glucose plus fructose), which you stir into your breakfast coffee; lactose (milk sugar: glucose plus galactose), found in the milk you pour in your coffee; and maltose (glucose plus glucose, which will form in your digestive tract as you break down the starch in the pancakes you may have for breakfast). When energy is required, the disaccharides are broken apart into their monosaccharide subunits by hydrolysis.
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Ex. 65. Translate the following text into Ukrainian.
Although all atoms of a particular element have the same number of protons, the number of neutrons may vary. Neutrons do not affect the chemical reactivity of an atom very much, but they do make their presence felt in other ways. First, neutrons add to the atom’s mass, which can be detected by sophisticated instruments such as mass spectrometers. Second, nuclei with “too many” neutrons break apart spontaneously, or decay, often emitting radioactive participles in the process. Those particles can also be detected – for instance, with Geiger [‘gaıgə] counters. The process in which a radioactive isotope spontaneously breads apart is called radioactive decay.
A particularly fascinating and medically important application of radioactive isotopes is positron emission tomography, more commonly know as PET scans. In a common application of PET scans, a subject is given the sugar glucose that has been labeled with (that is, attached to) a harmless radioactive isotope of fluorine. When the nucleus of fluorine decays, it emits two bursts of energy that travel in opposite directions along the same line. Energy detectors are arranged in a ring around the subject. They record the nearly simultaneous arrival of the two energy bursts. A powerful computer then calculates the location within the subject at which the decay must have occurred and generates a map of the frequency of fluorine decays. As the fluorine is attached to glucose molecules, this map reflects the glucose concentration within the subject’s brain. The brain uses prodigious amounts of this sugar for energy; the more active a brain cell is, the more glucose is uses. How can this information be used in biological research?
Let us suppose that a neuroscientist is trying to locate the areas of the brain that are involved in memory. The researcher might give fluorine-labeled glucose to a few volunteer subjects and then ask them to memorize a word list, which is read aloud. Because brain regions that are active during this process would need more energy and would take more fluorine-glucose molecules than they would be taken by inactive regions, the active regions would have more fluorine decays. The PET scans would be taken during the memorization and then pinpoint brain regions active in storing memories of words.
Physicians also use PET scans in the diagnosis of brain disorders. For example, brain regions in which epileptic seizures originate generally have excessively high glucose utilization and show up in PET scans as “hot spots”. Many brain tumors also light up in PET scans. Abnormal metabolism of certain brain regions may also be detected in patients with some mental disorders, such as schizophrenia [skıtsəu’fri:njə].
Ex. 66. Translate the following text into Ukrainian.
Within the past few years, the technologies of recombinant DNA have mushroomed. We will follow a typical sequence of procedures that might be used to solve a particular problem or to produce a specific product.
The first task in recombinant DNA technology is to produce a DNA library – a readily accessible, easily duplicable assemblage of all the DNA of a particular organism. The entire set of genes carried by a member of any given species is called a genome. Why build a DNA library of a species’ genome? A DNA library organizes the DNA in a way that researchers can use it. restriction enzymes, plasmids, and bacteria are the most commonly used tools in assembling a DNA library.
Many bacteria produce restriction enzymes, which sever DNA at particular nucleotide sequences. In nature, restriction enzymes defend bacteria against viral infections by cutting apart the viral DNA. (The bacteria protect their own DNA, probably by attaching methyl groups to some of the DNA nucleotides.) Researchers have isolated restriction enzymes and use them to break DNA into shorter strands at specific sites.
Most restriction enzymes recognize and sever palindromic sections of DNA, in which the nucleotide order is the same n one direction on one strand as in the reverse direction on other strand. (A palindrome is a word that reads the same forward and backward, such as “madam”.) These single-stranded cut pieces of the DNA fragment are called ‘sticky ends’, because they will stick to (form hydrogen bonds with) other single-stranded cut pieces of DNA with the complementary series of bases. If the appropriate DNA repair enzyme (called DNA ligase) is added, DNA from different sources cut by the same restriction enzyme can be joined as if the DNA had occurred naturally. Segments of DNA from fundamentally different types of organisms, such as bacteria and humans, can be joined if they have complementary sticky ends.
Many different restriction enzymes have been isolated from various species of bacteria. Each cuts DNA apart at different but specific palindromic nucleotide sequences. The variety of restriction enzymes has enabled molecular geneticists to identify and isolate specific segments of DNA from many organisms, including humans.
Suppose now that human DNA is isolated from white blood cells and is cut apart into many small fragments with a restriction enzyme. The same restriction enzyme is then used to sever the DNA of bacterial plasmids. Now both human and plasmid DNA have complementary sticky ends that, when mixed, form hydrogen bonds. When DNA ligase is added, it bonds the sugar-phosphate backbones together, inserting segments of human DNA into plasmids.
The new rings of plasmid-human DNA (recombinant DNA) are mixed with bacteria, which take up the recombinant DNA. Millions or billions of plasmids collectively could incorporate DNA from the entire human genome. Usually, 100 to 1000 times more bacteria than plasmids are used, so that no individual bacterium ends up with more than one recombinant DNA molecule. The resulting population of bacteria containing recombinant plasmid-human DNA constitutes a human DNA library.
Ex. 67. Translate the following text into Ukrainian.
A gene’s specific physical location on a chromosome is called a locus (plural, ‘loci’). Homologous chromosomes carry the same genes, located at the same loci. Although the nucleotide sequence at a given gene locus is always similar on homologous chromosomes, it may not be identical. These differences allow different nucleotide sequences at the same gene locus on two homologous chromosomes to produce alternate forms of the gene, called alleles. Human A, B, and O blood types, for example, are produced by three alleles of the same gene.
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If both homologous chromosomes in an organism have the same allele at a given gene locus, the organism is said to be homozygous at that gene locus. (“Homozygous” comes from Greek words meaning “same pair”.) If two homologous chromosomes have different alleles at a given gene locus the organism is heterozygous (“different pair”) at that locus and is called a hybrid. During meiosis, homologous chromosomes are separated, so each gamete receives one member of each pair of homologous chromosomes. Therefore, all the gametes produced by an organism that is homozygous at a particular gene locus will contain the same allele. Gametes produced by an organism that is heterozygous at the same gene locus are of two kinds: half of the gametes contain one allele, and half contain the other. (…)
Mendel’s choice of the edible pea as an experimental subject was critical to the success of his experiments. In plants, a male gamete, which for simplicity we’ll call the sperm, is contained in each pollen grain. The structure of the pea flower normally prevents another flower’s pollen from entering. Instead, each pea flower normally supplies its own pollen, so the egg cells in each flower are fertilized by sperm from the pollen of the same flower. This process is called self-fertilization. Even in Mendel’s time, commercial seed dealers sold many types of peas that were true-breeding. In true-breeding plants, all the offspring produced through self-fertilization are homozygous for a given trait and are essentially identical to the parent plant.
Although peas normally self-fertilize, plant breeders can also mate plants by hand, a process called cross-fertilization. Breeders pull apart the petals and remove the stamens, preventing self-fertilization. By dusting the carpels with pollen they have selected, breeders can control cross-fertilization. In this way, two true-breeding plants can be mated to see what types of offspring they produce.
In contrast to earlier scientists, Mendel chose to study traits – heritable characteristics – that are unmistakably different forms, such as white flowers versus purple flowers, and he worked with one trait at a time. These factors allowed Mendel to see through to the underlying principles of inheritance. Equally important was the fact that Mendel counted the numbers of offspring with each type of trait and analyzed the numbers. The use of statistics as a tool to verify the validity of results has since become an extremely important practice in biology.
Ex. 68. Translate the following text into Ukrainian.
Although nearly 100,000 species of modern fungi have been described, biologists have only begun to comprehend the diversity of these organisms – at least 1000 additional species are described each year. Like plants, fungi are grouped into divisions, which are comparable to animal phyla. The major divisions of fungi are the Zygomicota (zygote fungi), Ascomycota (sac fungi), Basidiomycota (club fungi), and Deuteromycota (imperfect fungi) (Table 1).
The zygomycetes, also called the zygote fungi, include about 600 species. Familiar – and annoying – zygomycetes are those of the genus Rhizopus, which cause soft fruit and black bread mold. The haploid hyphae of zygomycetes appear identical but are actually two different mating types. The two types “mate sexually”, fusing their nuclei to produce diploid zygospores. These resistant structures are dispersed through the air and can remain dormant until conditions are favorable for growth. Zygospores then undergo meiosis and germinate into structures that bear haploid spores. The spores then give rise to new hyphae. These hyphae may reproduce asexually, by forming haploid spores in black spore cases called sporangia, or sexually, by fusing to produce more zygospores.
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The 30,000 species of ascomycetes, also called sac fungi, are named after the saclike case, or ascus (plural, asci), in which their spores form during sexual reproduction. Some ascomycetes live in decaying forest vegetation and form beautiful cup-shaped reproductive structures or corrugated, mushroomlike fruiting bodies called morels. This division also includes many of the colorful molds that attack stored food and destroy fruit and grain crops and other plants. Some ascomycetes secrete the enzymes cellulase and protease, which can cause significant damage to cotton and wool textiles, especially in warm, humid climates where molds flourish. Ascomycetes cause both Dutch elm disease and chestnut blight, but other ascomycetes are a boon to plants, forming mutually beneficial associations with plant roots. A gastronomic delicacy, the truffle, is also a member of this diverse division.
Claviceps purpurea, an ascomycete that attacks rye plants, produce structures called ergots that release several toxins, one of which is the active ingredient in the drug LSD. If infected rye is made into flour and consumed, the toxins can lead to ergot poisoning – convulsions, hallucinations, and ultimately death. This happened frequently in northern Europe in the Middle Ages, but modern agricultural techniques have essentially eliminated the disease. Another Claviceps toxin has medicinal effects if administered in low doses; that toxin is currently used in drugs that induce labor and control hemorrhaging after childbirth.
Among the ascomycetes we also find the yeasts, some of the few unicellular fungi. The yeasts include both the parasitic yeast that is a common cause of vaginal infections and the baker’s and brewer’s yeasts that make possible the proverbial loaf of bread and jug of wine. Some yeasts form hyphae when nutrients are scarce; the hyphae can elongate and reach distant food sources.
Basidiomycetes are called the club fungi because they produce club-shaped reproductive structures. The division Basidiomycetes consists of about 25,000 species, including the familiar mushrooms, puffballs, and shelf fungi, sometimes called monkey-stools. Although several mushrooms species are considered delicacies, mushrooms can be deadly. Some members of the genus Amanita contain potent toxins that are among the most deadly poisons ever found. Basidiomycetes can also be dangerous to plants; they include some devastating plant pests descriptively called rusts and smuts, which cause billions of dollars worth of damage to grain crops annually. Some members of this group, however, enter into mutually beneficial relationship with plants.
Basidiomycetes typically reproduce sexually. Mushrooms and puffballs are actually reproductive structures: dense aggregations of hyphae that emerge under proper conditions from a massive underground mycelium. On the undersides of mushrooms are leaflike gills that produce specialized club-shaped diploid cells called basidia. Basidia give rise to haploid reproductive basidiospores by meiosis. These are released by the billions from the gills of mushrooms or the inner surface of puffballs and are dispersed by wind and water.
Falling on fertile ground, a mushroom basidiospore may germinate and form haploid hyphae of two different mating types. When the two types meet, some of the cells fuse and produce an underground mycelium. These hyphae grow outward from the original spore in a roughly circular pattern as the older hyphae in the center die. The subterranean body periodically sends up numerous mushrooms, which emerge in a ringlike pattern called a fairy ring. The diameter of the fairy ring can reveal the approximate age of the fungus – the wider the ring diameter, the older the mushrooms, and their average rate of growth is known. Some fairy rings are estimated to be 700 years old.
Deuteromycetes are called the imperfect fungi because none have been observed to form sexual reproductive structures. In some species the sexual stage has been lost during evolution; in others it may exist but has not yet been observed. This large division includes about 25,000 described species of great diversity and considerable importance to humans. It was a member of this division that contaminated and killed the bacterial cultures of the microbiologist Alexander Fleming by accident. His keen observations led to the isolation of penicillin, the first antibiotic, from the fungus Penicillium. We also owe to deuteromycetes the indescribable flavor and aroma of Roquefort and Camembert cheeses. Other imperfect fungi are human parasites, causing diseases such as ringworm and athlete’s foot. Some are not content to live on dead organisms or even to parasitize live ones – they act as predators, laying deadly traps for unsuspecting roundworms.
Ex. 69. Translate the following text into Ukrainian.
The immune system is a strange “system”. Unlike the nervous system, for example, it is not composed of physically attached structures. Instead, as befits its mission of patrolling the entire body for microbial invaders, the immune system consists of an army of separate cells. Nevertheless, the army is highly coordinated. This coordination requires complex communications involving antigens, antibodies, hormones, receptors, and cells. For example, when a virus invades the body (step 1), it sets off a cascade of events that can be loosely divided into three components.
One component of the immune response begins when macrophages ingest the virus (step 2) and digest it. Antigens that have been “chewed off” the virus become attached to certain proteins of the macrophage’s major histocompatibility complex (MHC) and are displayed, or presented, on the surface of the macrophage. These antigen-MHC complexes are recognized by virgin helper T cells (step 3). Next, receptors on helper T cells release a hormone called interleukin-2 (step 4). This hormone stimulates cell division and differentiation (step 5) in both the releasing cell and in any other T cells that have bound to an antigen-MHC complex. Some of the resulting daughter helper T cells become memory cells that provide future immunity (step 6); other daughter cells become mature T cells that assist in activating – that is, stimulating the immune response of – cytotoxic T cells and B cells (step 7).
Meanwhile, other copies of the virus are infecting ordinary body cells, such as those lining the respiratory tract (step 8). Infected body cells display viral antigens on their surfaces, bound to another set of MHC molecules. Virgin cytotoxic T cells bind to the antigen-MHC complex on the body cells (step 9) and are simultaneously activated by interleukin-2 released by the activated helper T cells. This combination of binding and stimulation causes the cytotoxic T cells to multiply and become activated (step 10). When activated cytotoxic T cells then encounter infected cells presenting the antigen-MHC complex, the T cells release toxic proteins that kill the infected cell by lysis (step 11).
Some B cells bear antibodies on their surfaces that bind antigens on the surface of free viruses that have not yet invaded a body cell (step 12). This antigen-antibody binding stimulates some B cell division and maturation, but full activation of B cells requires a boost from helper T cells. This boost is provided when B cells that have bound antigen ingest that antigen (by receptor-mediated endocytosis), attach the antigen to MHC molecules, and present the antigen-MHC complex on their surfaces. The antigen-MHC complex is recognized by activated helper T cells (step 13), which then release several types of interleukin hormones that stimulate the division and differentiation of antigen-binding B cells (step 14). Some of the progeny become memory cells (step 15); other become plasma cells that secrete antibodies into the bloodstream (step 16).
As you can see, helper T cells are essential in turning on both phases of the immune response. A loss of helper T cells, such as that caused by the virus that causes AIDS, virtually eliminates the immune response to many diseases.
Ex. 70. Translate the following text into Ukrainian.
The field of chemistry is now a very large one. There are more than 30 different branches of chemistry. Some of the better known fields are inorganic chemistry, organic chemistry, physical chemistry, analytical chemistry, biological chemistry, pharmaceutical chemistry, nuclear chemistry, industrial chemistry, colloidal chemistry, and electrochemistry.
Inorganic chemistry. It is originally considered that the field of inorganic chemistry consists of the study of materials not derived from living organisms|. However it now includes all substances other than the hydrocarbons and their derivatives.
Organic chemistry. At one time it was thought that all substances found in plants and animals could be made only by using part of a living plant or animal. The study of these substances, most of which contain carbon was therefore called organic chemistry. It is now known that this idea is quite wrong, for in 1828 F. Wohler made an "organic" substance using a simple laboratory process.
Organic chemistry now merely means the chemistry of carbon compounds.
Physical chemistry is concerned with those parts of chemistry which are closely linked with physics as, for in stance, the behaviour of substances when a current of electricity is passed through them.
Electrochemistry is concerned with the relation between electrical energy and chemical change. Electrolysis is the process whereby electrical energy causes a chemical change in the conducting medium, which usually is a solution or a molten substance. The process is generally used as a method of deposition metals from a solution.
Magnetochemistry is the study of behaviour of a chemical substance in the presence of a magnetic field. A paramagnetic substance, i.e. one having unpaired electrons is drawn into a magnetic field. Diamagnetic substances, i.e. those having no unpaired electrons, are repelled by a magnetic field.
Biochemistry. Just as the physical chemist works on the boundaries between physics and chemistry, so the biochemist works on the boundaries between biology and chemistry. Much of the work of the biochemist is concerned with foodstuffs and, medicines. The medicines known as antibiotics, of which penicillin is an early example, were prepared by biochemists.
Ex. 71. Translate the following text into Ukrainian.
Simple diatomic molecules of a single element are designated by the symbol for the element with a subscript 2, indicating that it contains 2 atoms. Thus the hydrogen molecule is H2; the nitrogen molecule, N2; and the oxygen molecule, O2. Polyatomic molecules of a single element are designated by the symbol for the element with a numerical subscript corresponding to the number of atoms in the molecule. Examples are the phosphorus molecule, P4, and the sulphur molecule, S8.
Diatomic covalent molecules, containing unlike elements are given similar designation. The formula for hydrogen chloride is HCl. The more electropositive element is always designated first in the formula.
For polyatomic covalent molecules containing unlike elements, numerical subscriptions are used to designate number of atoms of each element present in the molecule, for example, water, H2O. Again, as in diatomic molecules, more electropositive element is placed first in the formula.
Ex. 72. Translate the following text into Ukrainian.
One of the cornerstones of modern chemical theory is the Periodic Law. It can be simply stated as follows: The properties of the elements are a periodic function of the nuclear charges of their atoms.
In 1869 Mendeleyev arrived at the conclusion that by the arrangement of the elements in order of increasing atomic weight the similarity and periodicity of properties of various, valence groups of the elements were clearly delineated.
There were several vacant spaces in Mendeleyev's table which led him to predict the existence of six undiscovered elements, (scandium, gallium, germanium, polonium etc). His confidence in the new classification was clearly expressed in the predictions which he made of the chemical properties of these missing elements. And within fifteen years gallium, scandium and germanium were discovered.
Although this table has been modified hundreds of times, it has withstood the onslaught of all new facts. Isotopes, rare gases, atomic numbers, and electron configurations have only strengthened the idea of the periodicity of the properties of the elements.
Ex. 73. Translate the following text into Ukrainian.
Chlorine is an element with atomic number 17, atomic weight 35.5 (thirty-five point five). It is a gas at ordinary temperatures and is never found free in nature. It is found in nature combined with other elements. At normal temperatures, chlorine is a diatomic gas (C12), greenish-yellow in colour and about 2 1/2 (two and a half) times as heavy as air. It liquefies at atmospheric pressure at —34. 1° C (minus thirty-four point one degrees Centigrade) to a yellowish liquid approximately 11/2 (one and a half) times as heavy as water. The liquid freezes at —100.98° C (minus one hundred point nine eight degrees Centigrade). Chlorine is soluble in water and indirectly exerts bleaching and bactericidal action by reacting with water to form hypochlorous acid.
Cl2 + H2O ↔ HCl + HClO → HCl + (O)
Chlorine Water Hydrochloric Hypochloric
acid acid
The hypochlorous acid is unstable, giving up oxygen to form more HC1. The oxygen attacks and destroys bacteria; it also oxidizes coloured organic substances, forming colourless or less-coloured components.
As one of the most active elements, chlorine ranks in reactivity about with oxygen. It combines directly and readily with hydrogen and most non-metals except nitrogen, carbon and oxygen; it also unites with all the familiar metals except gold and platinum.
Participating in a number of important organic reactions, in some cases chlorine appears in the final product, as in insecticides (DDT) or in the plastic, polyvinil chloride.
Chlorine is generally produced by electrolysis of water solutions of sodium chloride in electrolytic cells. When sodium chloride or potassium chloride solutions are subjected to electrolysis, there are three products; caustic soda or caustic potash, chlorine and hydrogen. If fused sodium chloride is used, there are two products: chlorine, and metallic sodium.
Ex. 74. Translate the following text into Ukrainian.
The analysis of a complex material usually involves four steps, sampling, dissolving the sample, separating mutually interfering substances, and determining the constituents of interest. The first step, sampling can be a significant problem, particularly in industrial applications.
Sampling is complete when the subdivision is small enough to permit analysis.
The second step is the dissolving of a sample. If we know the nature of the sample we use a suitable reagent.
Gravimetric methods involve a weighing operation as the final measurement.
Gravimetric analysis have been developed for almost everything from A(luminium) to Z(irconium).
Gravimetric procedures may be done in various ways: by precipitating, by dissolving, by removing as a volatile compound.
Volumetric methods involve measurement of that volume of a solution of known concentration which reacts with a known amount of the sample. Such a solution is called a standard solution.
Volumetric techniques are now applicable to most of the elements and to many specific inorganic and organic compounds. They are widely used in all phases of chemistry, in medicine, and in many allied sciences.
Physico-chemical methods depend upon the measurement of physical properties other than mass and volume. Such methods are important when the simpler methods of analysis are inadequate.
Ex. 75. Translate the following text into Ukrainian.
Methods of separating a solid and a liquid are built around two processes, filtration and centrifugation.
Filtration is the process of passing the suspension of solid and liquified through a porous barrier which will trap the solid. The barrier may be filter paper, sintered glass, asbestos matting, glass wool and others.
Centrifugation is mechanized setting (or floating) and depends upon the difference between the densities of the solid and the solution. Gravitational setting is usually inadequate. A centrifuge can be used to enhance the gravitational force moving the particles. Most centrifuges operate at hundreds of revolutions per minute. Extremely difficult separations require speeds of tens of thousands of revolutions per minute.
Ex. 76. Translate the following text into Ukrainian.
Chromatography is a method of chemical analysis based upon the selective absorption and partial fractionation of various substances by certain suitable materials. The method is simple and requires a minimum of special equipment. The technique consists of pouring a solution through a column containing a suitable adsorbing material. A selective developing agent is then passed through the column and the different substances in the solution are spread down the column into layers visibly separated from one another, provided the substances are colored. In the case of colorless substances, the layers of the different substances may be located by the use of ultra-violet light or by chemical tests.
This method was first described by the Russian botanist Tswett, in 1906. Tswett was engaged in the extraction and purifictaion of plant pigments.
Methods of chromatography have been applied to the separation of the rare earths and a number of procedures, based on chromatography techniques, have been developed for the separation of the inorganic cations and anions.
Ex. 77. Translate the following text into Ukrainian.
The relative proportions of various components of gas mixtures can be determined by merely measuring some physical constants of the mixture: the density, the viscosity, the thermal conductivity, heat of combustion, ionization potential.
Condensation methods are often applicable in the separation of complex mixtures of gases. This method has been applied to the gases of the argon group and of natural gas mixtures.
The application of the methods of mass spectrometry to gas analysis has been extensive. The use of a mass spectrometer in analysis enables one to determine the components of mixtures of hydrocarbons, fuel gases, rare gases, etc.
Thermal conductivity applied to gas analysis is rapid, simple to carry out and adaptable to continuous operation.and process control.
Some attempts to apply the methods of emission and absorption spectroscopy to gas analysis have been made.
Other miscellaneous methods include magnetic susceptibility, micro-wave analysis, acoustical method based on the principle that the velocity of sound in a gas is a function of the molecular weight of the gas, inferometric methods, diffusion methods and others.
Ex. 78. Translate the following text into Ukrainian.
Liquid-liquid phase separations are possible when a metal forms a compound soluble in two immiscible liquids. The distribution of the compound between the two liquids can be considered to be a solubility contest. Practical considerations dictate that one of the liquids must be water. Among the liquids other contestants are: carbon tetrachloride, chloroform, carbon disulfide, ethers, paraffin hydrocarbons, and aromatic hydrocarbons. Alcohols cannot be added to this list.
Most inorganic compounds just are not interested in the organic solvents which are immiscible with water. Sometimes, however, a complexing agent can be found which will coach an inorganic substance into an organic solution. Cupric, lead, zinc, silver, mercuric, and cadmium salts, for example, will dissolve, in either chloroform or carbon tetrachloride if it contains some dithizone.
Ex. 79. Translate the following text into Ukrainian.
Alfred Bernard Nobel, a Swedish chemist, invented dynamite and founded the Nobel Prizes. As a young man, Nobel experimented with nitroglycerin in his father’s factory. He hoped to make this dangerous substance into a safe and useful explosive. He prepared a nitroglycerin explosive, but so many accidents occurred when it was put on the market that for a number of years many people considered Nobel almost a public enemy.
Finally in 1867 Nobel combined niter with an absorbent substance. This explosive could be handled and shipped safely. Nobel named it dynamite. Within a few years he became one of the world’s richest men. He set up factories throughout the world and bought the large Bofors armament plant in Sweden. He worked on synthetic rubber, artificial silk and many other products.
Nobel was never in good health. In later years he became increasingly ill and nervous. He suffered from a feeling of guilt at having created a substance that caused so much death and injury. He hated the thought that dynamite could be used in war when he had invented it for peace. Nobel set up a fund of about 9 million U.S. dollars. The interest from the fund was to be used to award annual prizes, one of which was for the most effective work in promoting international peace.
Alfred Nobel was born on October, 21, 1833 in Stockholm. He was the son of an inventor. He was educated in St. Petersburg, Russia, and later studied engineering in the United States.
Ex. 80. Translate the following text into Ukrainian.
Flip a switch and a light goes on. It's simple, right? Wrong! Every time you flip a light switch, you make billions of little electrons go to work for you. Uncountable hours of work have gone into providing you with the electricity you need to turn that light on. Without electricity you wouldn't have telephones, television, video games, and many other things you use every day.
Have you ever gotten a shock when you touched a doorknob, or seen sparks fly when you combed your hair? That's electricity. Electricity is a type of energy that gives things the power to work. This energy comes from electrons. Scientists have learned how to use electrons to produce electricity.
It takes billions of electrons to make electricity operate. Electrons move through an electric wire in much the same way water moves through a garden hose. Turning on the faucet pushes the water through the hose. Pushing electrons makes electricity move through the wire. The machine that pushes the electrons through the wire is called a generator. The wire from the generator goes to your home and into a control center, which is either a fuse box or a circuit breaker.
The fuse box controls how much electricity you use. If you try to use too much, you will "blow a fuse," and the electricity from that fuse will be cut off. A circuit breaker works differently from a fuse box. A circuit breaker does not let you use too much electricity. It cuts off the flow before there's an overload. If you did not have a fuse box or circuit breaker, your electric wires could overheat and start a fire! From the fuse box or circuit breaker, the wires go inside your walls to light switches and sockets. Turning on the light switch lets the electricity flow to the light, and the light goes on. When you put a plug into-a socket, electricity comes to the socket. But it doesn't flow into the lamp until the switch is turned on.
Besides turning on lights, we can use electricity to carry sound. Sound is made by vibrations called sound waves. The electricity in a telephone picks up the sound waves from the speaker on one end and carries them to the receiver on the other end. The electricity moves so fast that you can hardly notice the time it takes to travel from one place to another. When you turn on your TV, you get both light and sound, Again, it is electricity that makes this possible, allowing you to see and hear your favorite shows!
Ex. 81. Translate the following text into Ukrainian.
Sugar, rubber, glass, silver, milk, wood and modelling clay are all common substances. They are easy to tell apart and each one is useful in its own way. No one would think of trying to make an ink-pot out of milk, or a candle out of sugar. No one would make a bracelet of modeling clay, a dinner plate of silk. No one would try to drink wood or build a fire with water, no one would make a baseball bat of glass, or a baseball of silver. Every substance has, what scientists call, properties of its own. Yet all substances are alike in one way. They all weigh something, and they all take up room.
When scientists want to lump all substances together and talk about them, they use the word "matter". Every substance is a kind of matter. The science of physics is partly a study of matter. It explains how water can evaporate and become a gas as well as how it can freeze and become a solid. It explains why some substances are solids, some liquids, and some gases. It explains why butter melts more easily than iron and where a lump of sugar goes when it is put into hot coffee. It explains why a tire is more likely to blow out on a hot day than on a cold one. It explains many of the changes that go on around us.
But physics is also a study of energy – of light, heat, sound, electricity, magnetism, of the energy of moving bodies, and of atomic energy. One of the commonest of all questions is, "How does it work?" Many, many times we must go to the science of physics to get the answer. And most of the answers have something to do with energy.
How does television work? How fast does sound travel? How can a camera take a picture? What are cosmic rays? What are the problems in travelling through outer space? How does an airplane fly? These are a few questions that the science of physics answers.
Ex. 82. Translate the following text into Ukrainian.
1. A force is a push or pull which affects the motion of matter. Like energy, force cannot be weighed and does not take up space. However, force acts on matter to produce or prevent motion in a given direction. Although we cannot actually see force, we know it is present by the way it affects the movement of matter.
2. Does force always produce motion? In trying to lift a heavy object, it is possible to exert a great deal of force without moving the object. Thus all motion is caused by force, but not all forces produce motion.
3. When you pick up a book or throw a ball, you are using force to put the objects in motion. You may already know that energy is needed to produce motion in matter. Therefore, the force you exert in moving an object is actually produced by your muscles. When you ride in an automobile, you know that force is needed to move the car.
4. Force is also needed to slow down or stop the motion of an object. When you catch a ball, you use force to stop the motion of the ball. When you use the brake on a bicycle, you are using force to slow it down. To affect motion, force always requires some form of energy, such as mechanical, heat, electrical, chemical, or nuclear.
5. We know that gravity attracts all matter toward the centre of the Earth. Since a falling object is in motion, the attraction of gravity is a force that produces this motion in matter. We also know that the pull of gravity, commonly measured as the weight of an object, is greater on objects having more mass than on less massive objects. Does this difference in the pull of gravity affect the rate of speed with which an object falls?
6. Careful experiments have shown that the speed with which a n object falls from a given height is the same regardless of mass. That is, a heavy object falls at the same rate of speed as a light object. Of course, if you drop a feather and a coin 'from the same height, the coin strikes the ground first. The feather falls slower only because it has a larger surface area. It is held back by the amount of air that must be pushed aside to let it fall. This air friction opposes the motion of the feather. If a feather and a coin are placed in a tube and all the air is pumped out, you would discover that both objects fall at the same rate of speed.
7. There are forces which can overcome the force of gravity. An airplane rises above the ground because the forces acting on its wings lift it off the ground. A helicopter can come to a stop in the air because it is supported by the forces acting on its rotating wing. Rockets and spaceships can escape the Earth's gravitational pull when upward forces are produced that overcome their weights.
8. Scientists know that gravity is responsible for the holding together of our solar system and the entire Universe. Isaac Newton realized that every object on Earth and in space exerts a force of attraction on every other object, regardless of mass. This force of attraction is known as the law of universal gravitation.
Ex. 83. Translate the following text into Ukrainian.
Electricity has been known since the days of the ancient Greeks. The word "electricity" comes from the Greek word for amber. The Greeks discovered that, if a piece of amber was rubbed with fur, it would pick up bits of straw or other light-weight materials. Later scientists discovered that other materials would act like amber. They could be given charges of electricity. Charges of this kind are called charges of frictional, or static, electricity. They are not very useful.
2. In 1800 an Italian scientist named Volta found a way of getting an electric current. He invented an electric cell. But electricity became truly useful after Michael Faraday invented a machine to push electrons on their way. A machine which furnishes a current of electricity is called a genarator. Today we use both cells and generators.
3. A battery is made up of two or more electric cells joined together. We use batteries in such things as portable radios, flashlights, electric games, and automobiles. The current which comes to our houses, stores and offices and lights our streets comes from generators.
4. In buying and using electrical appliances there are some terms everyone needs to know. "Volt" is one. "Ampere" is another. "Watt" is a third. The push that forces a current through a circuit is measured in volts. A volt is a measure of electrical force. Most household appliances are built for a voltage of either 127 or 220.
5. An ampere is a measure of the strength of a current. Electric lamp bulbs are marked in watts. A watt is a measure of electrical power. A kilowatt is 1,000 watts.
Ex. 84. Translate the following text into Ukrainian.
1. All the millions of substances in the world are built of only about a hundred simple substances. We call these simple substances elements. The very smallest bit of an element is an atom. Iron, for instance, is one of the elements. The very smallest bit of iron is an atom of iron.
2. Atoms are so tiny that it is hard to imagine how tiny they are. In a thimbleful of air there are more atoms than you could count if you lived to be a million years old. Of course, atoms are too small to be seen even with powerful microscopes. We know about them only from the way they act.
3. There can be millions of different substances because atoms of different kinds can join together in different ways. Atoms of oxygen and atoms of hydrogen, for instance, can join to form water. They can join in different proportions to form hydrogen peroxide.
4. Atoms are so small that it is almost unbelievable that anything could be smaller. But atoms are made up of even smaller particles. Every atom has a centre, or nucleus. The nucleus of an atom always has in it one or more particles called protons. In the case of every element except hydrogen it has particles called neutrons in it, too. Travelling around the nucleus there are one or more tiny particles called electrons.
5. The atoms of a few rare elements gradually break down by themselves. They shoot out some of the particles they are made of. As they do, they give off energy, mostly in the form of heat and light. These elements, we say, are radioactive. Radium is one of them. Uranium is another.
6. About 30 years ago scientists found a way of splitting atoms artificially and making them give off energy. They used machines called atomsmashers to hurl parts of atoms against the nucleus of an atom with so much force that it would split the nucleus. The splitting of atoms is called atomic fission.
7. After they found out how an atom can be split, scientists found out how to use the splitting of one atom to set off the splitting of other atoms. They discovered, in other words, how to bring about a chain reaction. 8. In atomic fission it is the nucleus that is split. For this reason, atomic energy is often called nuclear energy. Now scientists have found how to control the splitting of atoms. They have worked out ways of making atomic fission supply a steady amount of energy and serve mankind. Some power stations are already using atomic energy to generate electricity for peaceful aims.
Ex. 85. Translate the following text into Ukrainian.
For many years, men used light and heat energy from the Sun and from fires, but they did not understand the nature of light and heat until quite recently. Near the end of the 19th century, scientists began to think of light as waves travelling through space, somewhat the way that waves move over water.
As the problem was explored, it seemed that there should be other forms of energy which travel in the same way that light does. This study led to the discovery of radio waves which are somewhat like light waves. They both travel at the same speed and go out in all directions, or radiate, from one sport. They have been called radiant energy.
Radiant energy waves, though often explained by comparing them with water waves, or sound waves, are unlike anything else in the Universe. Water waves occur in water. Sound waves occur in the air, or other material. But radiant energy waves need no material to carry them from place to place. This seemed so unbelievable to scientists that for years they pretended that space was filled with a substance called ether, through which light, radio and other waves of radiant energy travelled.
The number of waves which are passing a given point in a second is the frequency. In sound, we know that the greater the frequency, the higher the pitch that we hear. Experiment shows that the short, high-frequency light waves are seen as violet in colour, while the longer, low-frequency waves are seen as red in colour. Some radiant energy waves, such as X-rays, are so short and have so high a frequency that they cannot be seen at all. Others, such as radio waves, are so long and have so low a frequency that you do not know they are present. Scientists learn about them only by experimenting and using sensitive instruments.
It is known that a current in a wire produces a magnetic field about it. If the current goes back and forth, or oscillates, a wave is set up which moves through space with the speed of light. These are radio waves. They have all the properties of other waves of radiant energy.
Radio broadcasting stations, television studios, radar sets, and signals from satellites all depend upon radiant energy waves for their operation.
Ex. 86. Translate the following text into Ukrainian.
As its name suggests, nuclear physics is the study of the central cores (nuclei) of atoms. An atomic nucleus is a tightly knit group of particles called protons and neutrons. Since protons are positively charged and neutrons are uncharged, the nucleus as a whole carries a positive charge. Virtually the whole weight of an atom is concentrated in its nucleus. Any atom of any one chemical element contains the same number of protons. This is its atomic number. But atoms of the same element may contain different numbers of neutrons. An element may therefore have more than one atomic weight. Hydrogen has just one proton in its nucleus (and so it is element number 1 in the periodic table). But deuterium, or heavy hydrogen, has a neutron as well as a proton in its nucleus. Its atomic weight is therefore 1 + 1=2. Elements like hydrogen and deuterium, that have the same atomic number but different atomic weights, are called isotopes. Nearly all the elements occurring in nature are stable but many isotopes are radioactive, i.e. their nuclei break up, throwing out rays and particles. The nuclear physicist can make radioactive isotopes by bombarding elements with atomic particles in an atom-smasher, or particle- accelerator. This may be one of several types, such as cyclotrons, synchrotrons or linear accelerators. But the most fruitful source of radioactive isotopes for use as "tracers" in a wide variety of applications is the nuclear reactor. A reactor is used for controlling the type of nuclear disintegration called a chain reaction, when the products are able to trigger off the break-up of further atoms.
Ex. 87. Translate the following text into Ukrainian.
In 1916, Albert Einstein published his General Theory of Relativity; this was to do for the 20th century what Newton's work had done for the 17th.
In 1907, at the age of twenty-eight, Einstein began digging at the roots of Newtonian mechanics. This re-examination of the fundamental premises of classical physics was prompted by Einstein's earlier work. Nearly two years before, while a clerk in a Swiss patent office, he had established an international reputation with the publication of a brief Special Theory of Relativity. This revolutionary theory, which was to lead ultimately to the liberation of atomic energy, introduced several profound ideas which differed greatly from those proposed by Newton.
Einstein showed that the Newtonian view was only an approximation of reality. But as it turns out, it proves to be a remarkably close approximation and so continues to be of fundamental importance to the world of science.
In the service of scientists, Newton's mechanics still explains the motion of planets, the Moon, artificial satellites, interplanetary space vehicles, tides, airplanes, automobiles – in fact for any kind of motion in which the relativistic increases in mass do not become important. They become important, as Einstein showed in his Special Theory of Relativity, when the speed of light is approached. And even when the speed of light is approached, suitable corrections can easily be made in Newton's laws to compensate for relativity effects.
As for the applications of Einstein's theory, it provides us with guidance in the field of cosmology, which deals with the large-scale 49 features of the Universe and with its history. But perhaps most important of all, general relativity has added to our understanding and our appreciation of the Universe.
Ex. 88. Translate the following text into Ukrainian.
The Universe contains many millions of stars in space. Vast collections of stars, known as galaxies, stretch out into space far beyond the visibility of the most powerful telescopes.
Galaxies exist in various shapes and sizes. The majority may be classed according to their shape as spiral, elliptical or irregular galaxies. The Milky Way, the galaxy in which our own solar system occurs, is of the spiral type. Seen in the night sky as a haze of white light stretching from the horizon, it is in fact a collection of perhaps 100,000 million stars. Our own Sun is not in the centre of it, but near the edge. The Milky Way is also known to astronomers as the Galaxy.
Some of the patches of light which can be seen in the sky are not so much galaxies as patches of incandescent (glowing) gas which may in time become stars. The origin of the Universe and its galaxies is not known. Some astronomers believe that matter is being continually created, though others believe that the Universe started by the explosion of concentrated matter. Both theories are difficult to prove.
Asteroids. An asteroid is a small or minor planet which circles the Sun. The distance from the Sun of such an asteroid varies greatly as it moves in its path around the Sun. There are many thousands of asteroids moving round the Sun between the orbits of Mars and Jupiter.
Most asteroids are very small, less than 20 miles in diameter. The largest is Ceres, which measures some 480 miles across. It is thought by some scientists that the origin of these minor planets is to be found in the breaking-up of a much larger body many thousands of 50 years ago. A characteristic feature of many of the asteroids is that their orbits are elongated ellipses.
Ex. 89. Translate the following text into Ukrainian.
Of all the planets in the solar system the planet Mars is probably the one which stimulates the greatest interest and which poses some interesting problems to the observers. In one curious way this planet differs from all the others. Each and every one of these planets presents itself in a suitable position for study every year, or at intervals of approximately every 12 months.
This is not the case with the planet Mars, for this planet presents itself for study at intervals of about 2 years and 2 months (780 days). A "day" on Mars is about 24 ½ hours. The Martian year is 687 days: it takes 687 of our days for Mars to complete one revolution about the Sun. However, because Mars travels more slowly than the Earth, it takes 780 days before the two bodies come into line. When the Earth and the planet Mars are in a line with the Sun, and on the same side of it, then Mars is in opposition and so at its best position for study.
Mars is a little over half the size of the Earth and it has a diameter of about 4,200 miles. As this planet is rather small, it can be 51 observed easily only around the times of opposition, when it is near the Earth. These oppositions occur about every 2 years and 2 months. Mars has a very elliptical orbit and opposition distances ca n vary from 62 million to 35 million miles. A favourable opposition, when Mars is as close to the Earth as it can be, takes place every 15 or 17 years.
Man's knowledge of Mars comes not only from the use of powerful telescopes but also from the use of unmanned spacecraft. Since 1962 Soviet and American spacecrafts have been travelling great distances in space to photograph and collect data about Mars and other planets. The pictures and the information are then sent back to Earth by means of radio and television signals.
Ex. 90. Translate the following text into Ukrainian.
Everyone has seen the Moon shining brightly in the sky on a clear night. The Moon is our natural satellite because it revolves in an orbit around the Earth. On the average, it is about 240,000 miles away. This is a short distance when we think of the vast distances between planets. The Moon is a rather large satellite with a diameter of a little more than 2,000 miles.
We have learned that there is no water on the Moon, and it has no atmosphere. The surface of the Moon has steep mountains and deep valleys. There are also large flat plains, which early astronomers thought were "seas", and large circular craters scattered on the surface. The surface of the Moon remains rugged and forbidding because there is no atmosphere. As a result, there is no weather to wear down the rocks. As the Moon revolves around the Earth, sunlight strikes its surface, and we see its reflected light in the Earth.
Since the Moon revolves around the Earth in our month, it takes a little over a week for the Moon to move one-quarter the distance around in its orbit. The Moon rotates on its axis and revolves around the Earth once each 27 1/3 days. However, since the Earth and the Moon are both moving around the Sun, it takes the Moon a little over two more days to catch up with the new position of the Earth. Hence, for an observer on the Earth, it is 29 ½ days between the one new Moon and the next. Automatic stations, space laboratories, the Soviet "Lunokhod" and the flight of the American astronauts to the Moon have begun a new period in exploration of the Moon.
