Showing papers in "Nature in 1949"
TL;DR: In this article, the authors define and examine a measure of concentration in terms of population constants, and examine the relationship between the characteristic and the index of diversity when both are applied to a logarithmic distribution.
Abstract: THE 'characteristic' defined by Yule1 and the 'index of diversity' defined by Fisher2 are two measures of the degree of concentration or diversity achieved when the individuals of a population are classified into groups. Both are defined as statistics to be calculated from sample data and not in terms of population constants. The index of diversity has so far been used chiefly with the logarithmic distribution. It cannot be used everywhere, as it does not always give values which are independent of sample size ; it cannot do so, for example, when applied to an infinite population of individuals classified into a finite number of groups. Williams3 has pointed out a relationship between the characteristic and the index of diversity when both are applied to a logarithmic distribution. The present purpose is to define and examine a measure of concentration in terms of population constants.
10,077 citations
TL;DR: Wentzel and Jauch as discussed by the authors described the symmetrization of the energy momentum tensor according to the Belinfante Quantum Theory of Fields (BQF).
Abstract: To say that this is the best book on the quantum theory of fields is no praise, since to my knowledge it is the only book on this subject But it is a very good and most useful book The original was written in German and appeared in 1942 This is a translation with some minor changes A few remarks have been added, concerning meson theory and nuclear forces, also footnotes referring to modern work in this field, and finally an appendix on the symmetrization of the energy momentum tensor according to Belinfante Quantum Theory of Fields Prof Gregor Wentzel Translated from the German by Charlotte Houtermans and J M Jauch Pp ix + 224, (New York and London: Interscience Publishers, Inc, 1949) 36s
2,935 citations
TL;DR: It would appear that rapidity of freezing is less important than the avoidance of surface effects, and Revival is far better when semen is frozen in bulk than when minimal amounts in capillary tubes are used.
Abstract: THE effect on spermatozoa of vitrification at temperatures of –79° C. and below has been studied by several authors. Human spermatozoa appear to be the most resistant ; a substantial proportion may show good motility on thawing after even prolonged vitrification. Revival is far better when semen is frozen in bulk than when minimal amounts in capillary tubes are used1. No explanation of this result is yet forthcoming, but it would appear that rapidity of freezing is less important than the avoidance of surface effects.
1,919 citations
TL;DR: Progress in this important field has depended upon the development of methods for identifying and determining the individual esters present in mixtures, but these methods frequently fail to yield diagnostic results.
Abstract: PHOSPHORIC esters play a central part in the biological world bY linking processes of respiration and fermentation with other essential cellular reactions. More tnan twenty substances of this group, mainly sugars and related substances esterified with phosphoric acid, are known to form intermediate in the network of enzymic reactions associated with the breakdown and interconversion of carbohydrates in plants and animals. Both in the intact cell and in the isolated enzyme systems in which these reactions are studied, phosphoric esters usually occur in mixtures, and progress in this important field has depended upon the development of methods for identifying and determining the individual esters present in such mixtures. Existing methods of analysis depend mainly upon the fractionation of salts of the esters and the selective hydrolysis of some of them, under standard conditions, these procedures being supplemented when possible by methods based on more specific reactions given by particular esters. Except when applied to certain relatively simple mixtures, these methods frequently fail to yield diagnostic results.
1,804 citations
TL;DR: The use of ammoniacal silver nitrate solution as a spraying reagent for revealing the presence of sugars on filter-paper chromatograms has the advantage of general application but has a corresponding disadvantage in reacting with a very wide range of reducing substances other than the sugars, including various impurities commonly present in such solvents as phenol and collidine.
Abstract: THE use of ammoniacal silver nitrate solution as a spraying reagent for revealing the presence of sugars on filter-paper chromatograms1 has the advantage of general application ; but it has a corresponding disadvantage in reacting with a very wide range of reducing substances other than the sugars, including various impurities commonly present in such solvents as phenol and collidine. Two-dimensional chromatograms are often rather unsatisfactory when ammoniacal silver nitrate is used, because (a) a rather large amount of the sugar mixture is needed and this increases the effect of interfering substances, (b) it is necessary to apply the spray as an aqueous solution, and unless the spraying is very rapid and uniform, the sugar spots migrate from wet to dry regions on the filter paper.
1,361 citations
TL;DR: From a comparison of vapour pressures and viscosities of solutions, it is deduced that in many cases the following equation yields closer agreement with experimental results: where d is a characteristic constant of the system.
Abstract: ARRHENIUS1 proposed the following expression for the viscosity of a solution : where ηs is the viscosity of the solution ; N1 and η1 are the mole fraction and the viscosity of component 1 ; N2 and η2 the mole fraction and the viscosity of component 2. However, both positive and negative deviations from this equation are found to occur. From a comparison of vapour pressures and viscosities of solutions, we deduced that in many cases the following equation yields closer agreement with experimental results : where d is a characteristic constant of the system. The accompanying graph shows curves calculated according to equations 1 and 2 (with d = -0·0224) for the system trans-decalin—cis-decalin. The points on the graph represent the experimental results of Bird and Daly2.
1,064 citations
TL;DR: It appears not to be generally known that the sex of a somatic cell as highly differentiated as a neurone may be detected with no more elaborate equipment than a compound microscope following staining of the tissue by the routine Nissl method.
Abstract: Geneticists have long emphasized that ‘maleness’ and ‘femaleness’, so far as chromosome content is concerned, are projected from the fertilized ovum into the morphologically and functionally specialized somatic cells. It appears not to be generally known, however, that the sex of a somatic cell as highly differentiated as a neurone may be detected with no more elaborate equipment than a compound microscope following staining of the tissue by the routine Nissl method.
966 citations
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TL;DR: The Wealth of India: A Dictionary of Indian Raw Materials and Industrial Products as mentioned in this paper is a dictionary of the economic products of India that was published during the years 1889-99 by the Government of India.
Abstract: IT may occasion some surprise to those men of science who are ill-acquainted with India, and who so frequently express the view that Governments are unappreciative of the importance of science to learn that as far back as 1886 the Government of India arranged for Dr. George (later Sir George) Watt, professor of botany in the Presidency College, Calcutta, to prepare a "Dictionary of the Economic Products of India". The six volumes of this standard work were published during the years 1889-99. In 1908 Sir George Watt published a condensed version, "The Commercial Products of India". Whatever the defects of these 'dictionaries', they have been of inestimable value to all interested in Indian natural products. The Wealth of India A Dictionary of Indian Raw Materials and Industrial Products. Raw Materials, Vol. 1. Pp. xxvii+254+39 plates. 15 rupees ; 24s. Industrial Products, Part 1. Pp. xii+182+8 plates. 8 rupees ; 12s. (New Delhi : Council of Scientific and Industrial Research, 1948.)
694 citations
TL;DR: Hille's seminal work on functional analysis and semi-groups as discussed by the authors is one of the most important mathematical books of the century, and should be read seriously by every mathematician, especially in the context of semi-group analysis, where abstract spaces, linear operations, vector-valued functions, and general analysis in Banach algebras are used.
Abstract: THIS work of Prof. Einar Hille is one of the important mathematical books of the century ; it should be read seriously by every mathematician. The subject of semi-groups is one of great and growing importance, and the type of analysis on which its treatment is based—abstract spaces, linear operations, vector-valued functions, and general analysis in 'Banach algebras'—is scarcely less important. Functional Analysis and Semi-Groups By Prof. Einar Hille. (American Mathematical Society: Colloquium Publications, Vol. 31.) Pp. xi + 528. New York: American Mathematical Society, 1948.) 7.50 dollars.
633 citations
TL;DR: This book is not a general treatise on vision, but in deals with some additions to visual physiology in the last fifteen years that have been derived from the study of action potentials of the retina and the optic nerve, and particularly with work in this field with which the author has been closely associated and in which his laboratory has been notably active.
Abstract: THIS book is not a general treatise on vision, but in deals with some additions to visual physiology in the last fifteen years that have been derived from the study of action potentials of the retina and the optic nerve, and particularly with work in this field with which the author has been closely associated and in which his laboratory has been notably active. It has been possible in many types of visual sense organ to record nerve impulse discharges set up by the stimulus of light ; in work on a simple eye (Limulus), Hartline showed that visual sense cells, like other sensory nerve endings that have been investigated, set up impulses of frequency related to the strength of the stimulus, and Hartline later confirmed this for single opticnerve fibres from the frog's retina. But here the response was complicated by fibres responding when the light was extinguished—the well-known off-discharge found by Adrian and R. Matthews in the eel's optic nerve. Granit's work has extended this investigation to mammalian eyes ; and the response in single optic-nerve fibres in many eyes has been studied and related to the wave-length of the light evoking it. Sensory Mechanisms of the Retina With an Appendix or Electroretinography. By Dr. Ragnar Granit. Pp. xxiii+412. (London, New York and Toronto : Oxford University Press, 1947.) 35s. net.
549 citations
TL;DR: Friedrichs as discussed by the authors described the dynamics of gases at speeds small compared with that of sound in a few dozen pages and showed that the phenomena show fascinating differences from those of classical physics.
Abstract: TWENTY-FIVE years ago what was known on the dynamics of gases, if acoustics and the study of steady motion at speeds small compared with that of sound (when the flow resembles that of a liquid) be omitted, could have been expounded in a few dozen pages. Since then, and more rapidly since 1943, the subject has grown into one which no single book can describe in its entirety. The primary stimulus was the increase in aircraft speeds ; but a secondary stimulus, the belated realization of workers in pure science that the phenomena show fascinating differences from those of classical physics, has become equally important. Supersonic Flow and Shock Waves By R. Courant K. O. Friedrichs. (Pure and Applied Mathematics, a Series of Texts and Monographs, Vol 1.) Pp. xvi + 464. (New York and London: Interscience Publishers, Inc., 1948.) 42s.
TL;DR: Bigelow and Schroeder as discussed by the authors published the first volume of "Fishes of the Western North Atlantic Part 1: Lancelets, by Henry B. Bigelow Isabel Perez Paufante, and William C. Schroeder.
Abstract: FROM the time of its appearance half a century ago, Jordan and Everyman's "Fishes of North and Middle America"has until to-day remained the only comprehensive descriptive account of the fishes of the western Atlantic Ocean. Much new knowledge has become available during this long period, and the time is now ripe for a new and up-to-date publication covering approximately the same field. The appearance of Volume 1 of "Fishes of the Western North Atlantic" is therefore most welcome and will supply a much-felt need. This volume, the first of a projected series, brings to fruition the. initial part of a plan conceived in New Haven a considerable time ago. With the establishment of the Sears Foundation for Marine Research at Yale University in, 1937, funds became available for publication on auite an ambitious scale, and a group of expert ichthyologists met to discuss the preparation of a work such as is now appearing. Fishes of the Western North Atlantic Part 1: Lancelets, by Henry B. Bigelow Isabel Perez Paufante; Cyclostomes, by Henry B. Bigelow and William C. Schroeder; Sharks, by Henry B. Bigelow and William C. Schroeder. (Sears Foundation for Marine Research, Memoir No. 1.) Pp. xvii+576. (New Haven, Conn.: Yale University, 1948.) 10 dollars.
TL;DR: A STUDY of isolated chromosomes has shown that they contain desoxyribonucleic acid, histone and another protein of an entirely different character from a histone1, which is the basis for the thread-like structure of the chromosome.
Abstract: A STUDY of isolated chromosomes has shown that they contain desoxyribonucleic acid, histone and another protein of an entirely different character from a histone1. This protein remains as a microscopic fibre after extraction of desoxyribonucleic acid and histone from the chromosome. The coiled thread that is left after removing desoxyribonucleic acid and histone is called a 'residual chromosome', and the protein of the thread is referred to as the 'residual protein' of the chromosome. Some ribonucleic acid is combined with residual protein. The thread of residual protein is the basis for the thread-like structure of the chromosome. In the isolated chromosomes that were first prepared, those of nucleated erythrocytes of the carp and of calf thymus, the residual protein represented only 4 and 8·5 per cent respectively of the dried mass of the total chromosome, the remainder of the lipid-extracted chromosome being almost entirely nucleohistone.
TL;DR: The Encyclopaedia of Chemical Technology as discussed by the authors is the first volume of a projected series of ten volumes, two to three volumes being due each year, with the object of the series being to provide an up-to-date survey of the field of chemical technology, partly as a reference for chemists and chemical engineers working in industry, and partly as an aid in training students in modern technology.
Abstract: THESE two volumes of nearly a thousand pages each are the first of a projected series of ten volumes, two to three volumes being due each year. The object of the series is to provide an up-to-date survey of the field of chemical technology, partly as a work of reference for chemists and chemical engineers working in industry, and partly as an aid in training students in modern technology. A large number of separate articles, written by specialists in the several fields, are presented in these two volumes; many chemical compounds are included, with extensive data on their physical and chemical properties and indications as to applications and processes of industrial manufacture. These articles are of interest not only to the technologist but also to the academic chemist, since they show the relation between the substances which they normally use in the laboratory with the wider world of technology. Care has been taken to use nomenclature which provides easy reference. A bibliography relative to each main item is given. There is also information about manufacturing costs and methods of packing materials for transport; these may not, however, be applicable outside the United States. This reservation applies also to the description of aluminium alloys, which are referred to by their code names. Encyclopaedia of Chemical Technology Edited by Raymond E. Kirk Donald O. Othmer. Vol. 1: A to Anthrimides. Pp. xxiv + 982. 20 dollars. Vol. 2: Anthrone to Carbon-Arc. Pp. xvi + 915. 20 dollars. New York and London: Interscience Publishers, Inc.
TL;DR: Di-p-xylylene as discussed by the authors was proposed as a trivial name for a hitherto undescribed hydrocarbon, the structure of which has been determined solely by X-ray diffraction to be tricyclo.
Abstract: POLYMERIZATION products from p-xylene have been shown to contain, inter alia, a hitherto undescribed hydrocarbon, the novel structure of which has been determined solely by X-ray diffraction to be tricyclo [8 : 2 : 2 : 24:7] hexadeca-4 : 6 : 10 : 12 (1) : 13 : 15-hexaene. We propose as a suitable trivial name 'di-p-xylylene'.
TL;DR: The range of light intensity available, however, has been limited by that obtainable from the sun and from high pressure mercury vapour lamps, the total usable output of which in the region between 2,000 and 5,000 A does not exceed 1020 quanta/second.
Abstract: IT has been a matter of general experience that photochemical reactions are not much altered in their courses by change of light intensity The range of light intensity hitherto available, however, has been limited by that obtainable from the sun and from such sources as high-pressure mercury vapour lamps, the total usable output of which in the region between 2,000 and 5,000 A does not exceed 1020 quanta/second There are many cases, particularly those photochemical reactions where free radicals are involved, where it would be desirable to extend investigations to much higher intensities into the region where the concentration of intermediates is comparable with that of the reactants
TL;DR: The theory of nucleation in the formation of liquid or solid phases from the vapour, the most detailed treatment of which in any published work is that by Becker and Doring1,2, is in satisfactory quantitative agreement with experiment with regard to the primary nucleation of liquid droplets1,3, which requires saturation ratios of from 3 to 6 in typical cases as mentioned in this paper.
Abstract: THE theory of nucleation in the formation of liquid or solid phases from the vapour, the most detailed treatment of which in any published work is that by Becker and Doring1,2, is in satisfactory quantitative agreement with experiment with regard to the primary nucleation of liquid droplets1,3, which requires saturation ratios of from 3 to 6 in typical cases. The theory predicts further that the primary nucleation of a crystal from the vapour requires still larger saturation ratios, so that the critical conditions for nucleation of the liquid are reached first, unless working with very low vapour pressures far below the melting point. This is also in agreement with observation.
TL;DR: In the elucidation of the mechanism of the reactions between hydrogen peroxide and ferrous and ferric ions, a considerable advance was made by Haber and Weiss2, who suggested that the highly reactive intermediates which have been shown to be present were the radicals HO and HO2 as mentioned in this paper.
Abstract: IN the elucidation of the mechanism of the reactions between hydrogen peroxide and ferrous and ferric ions, a considerable advance was made by Haber and Weiss2, who suggested that the highly reactive intermediates which have been shown to be present were the radicals HO and HO2. Their mechanisms, recently revised by Weiss2, are as follows:
TL;DR: In this article, Zener uses the term "anelasticity" to describe the properties of solids, as a result of which stress and strain are not uniquely related.
Abstract: WHEN metals are submitted to stress, the stress/swain relation is generally regarded as consisting of two parts, the elastic region and the region bfsplastiwin which a permanent set remains upon the remova of the stress. In the elastic region the absence of a permanent set does not necessarily imply that the relation between stress and strain is linear of even single-valued. Prof. Zener uses the term ‘anelasticity’ to describe the properties of solids, as a result of which stress and strain are not uniquely related. Examples are the elastic after-effect, the dependence of elastic constants on the method of measurement, and the dissipation of energy during vibration, which is often referred to as the damping capacity or internal friction of a solid. These effects have aroused much interest in recent years, largely owing to Prof. Zener's own work, and a good book on the subject is much to be desired. Elasticity and Anelasticity of Metals By Clarence Zener. Pp. x + 170. (Chicago: University of Chicago Press, London: Cambridge University Press, 1948.) 4 dollars.
TL;DR: Neither trypsin nor chymostrypsin exercises any dissolving effect upon the elastic fibres of the arteries; therefore, it can be concluded that the elastase is not identical with the known proteolytic enzymes.
Abstract: WE have reported in earlier communications1,2 that the extract of fresh pancreas as well as that of acetone-dried pancreas powder contains a specific enzyme which we called 'elastase'. This enzyme had not been found before in the human or animal organism ; but it was studied first by Eijkman3 so early as 1904 as a product of bacteria. The elastase of the pancreas dissolves the elastic fibres of the arteries. We found that in the wall of the arteries only the elastic fibres are attacked by this ferment, and the collagen remains unaltered. We have been able to show that our pure elastase differs from other proteolytic ferments of the pancreas such as trypsin and chymotrypsin. Through the kindness of Dr. J. H. Northrop, of Princeton, N.J., we obtained crystalline trypsin and chymotrypsin, and we tested the elastolytic power of these enzymes parallel with our elastase. Neither trypsin nor chymostrypsin exercises any dissolving effect upon the elastic fibres of the arteries ; therefore, we can conclude that the elastase is not identical with the known proteolytic enzymes.
TL;DR: In this paper, the same conclusion has been formulated by Pascual Jordan, but with an important modification, whereby the conservation law is not violated, which is achieved by taking account of the loss of gravitational energy connected with the creation of particles.
Abstract: Introduction IN a fascinating article which appeared in Nature of February 6, under the title “Stellar Evolution and the Expanding Universe, Mr. F. Hoyle has brought forward convincing arguments for the permanent creation of matter in space. Many physicists will find it difficult to accept this hypothesis. For if there is any law ‘which has withstood all changes and revelutions in physics, it is the law of conservation of energy, which according to Einstein's formula E = mc2 is equivalent to the conservation of mass. The same strange conclusion has, during recent years, been formulated by Prof. Pascual Jordan, but with an important modification, whereby the conservation law is not violated. This is achieved by taking account of the loss of gravitational energy connected with the creation of particles. As Jordan's papers do not seem to be known to many English-speaking physicists, I have asked him to write a short report of his work, and the following article is a translation of his article made by my collaborator, Dr. H. S. Green.
TL;DR: Interest in the sharpening, and in certain cases the displacement and splitting, of absorption bands at very low temperatures has hitherto been limited to the field of molecular physics.
Abstract: INTEREST in the sharpening, and in certain cases the displacement and splitting, of absorption bands at very low temperatures has hitherto been limited to the field of molecular physics, in so far as these changes have offered useful information on the molecular structure of a number of substances1,2.
TL;DR: Mott and Gurney's book on electrons in ionic crystals, the authors, is an excellent and perhaps the first monograph on applied theoretical physics and has been used for many applications of modern theoretical physics to questions of appreciable technical importance.
Abstract: THE last decade has seen an increasing number of applications of modern theoretical physics to questions which are of appreciable technical importance Often such applications arise from problems which at an earlier stage of development were of interest for the investigation of more fundamental properties of atoms and electrons. Mott and Gurney's book on electrons in ionic crystals, of which the second edition is now available, is an excellent and perhaps the first monograph on what might be called applied theoretical physics. Electronic Processes in Ionic Crystals By N. F. Mott Dr. R. W. Gurney. (International Series of Monographs on Physics.) Second edition. Pp. xii + 276. (Oxford: Clanendon Press; London: Oxford University Press, 1948.) 25s. net.
TL;DR: The first volume of the "Advances in Electronics" as discussed by the authors was published in 1948, and it was the first volume to cover the whole range of physics, but it was felt that electronics, though a part of physics and had grown to such a size that a volume of review articles confined to electronics was needed.
Abstract: THE “Reports on Progress in Physics” have always fulfilled a valuable function in acquainting the specialist in any one of the physical sciences with progress in cognate subjects. These “Reports” cover the whole range of physics, and it was felt that electronics, though a part of physics, so spilled over into electrical engineering and had grown to such a size that a volume of review articles confined to electronics was needed. Dr. L. Marton, now of the Bureau of Standards, has undertaken this task as editor, and the first volume has just been published. Although this is an American publication, it intends to draw freely upon European men of science for review articles, and already plans for volumes 2 and 3 include a number of British contributors. Volume 1 is written entirely by American men of science, but this was due to the difficulties encountered in launching the new venture. Advances in Electronics Edited by L. Marton Vol 1. Pp. xi+475. (New York: Academic Press, Inc.; London: H. K. Lewis and Co., Ltd., 1948.) 9 dollars.
TL;DR: An Introduction to the Theory of Seismology by Prof K E Bullen Pp xiv + 276 (Cambridge: At the University Press, 1947) 18s net as discussed by the authors.
Abstract: IN view of the number of different lines of approach, a borderline subject is apt to amass a vast literature, some of it difficult of access to investigators This is particularly true of seismology ; the phenomena of earthquakes have attracted the attention of many famous geologists, and the recording of earthquake tremors involves the methods of experimental physics, while the interpretation of the records of earthquakes has provided a great stimulus to the development of the theory of the propagation of disturbances in elastic media and has ultimately thrown considerable light on the composition of the interior of the earth Many books have been written on seismology in its various aspects, but many of the most interesting modern geophysical developments have hitherto been available only in the original papers It is therefore of considerable interest to read the elegant exposition that Prof K E Bullen has presented in the book under review An Introduction to the Theory of Seismology By Prof K E Bullen Pp xiv + 276 (Cambridge: At the University Press, 1947) 18s net
TL;DR: Recent investigations seem to provide a consistent theory leading to an explanation of growth in its general course as well as in its specific peculiarities, to quantitative laws allowing calculation and prediction, and towards a unification of the great physiological realms of metabolism, growth and form development.
Abstract: ORGANIC growth is, without doubt, one of the basic biological phenomena. Physiology presents a wide realm of experiences concerning factors influencing growth ; however, the phenomenon of growth itself remains, as yet, unexplained. Many growth formulae have been proposed, but none has been generally accepted. Recent investigations, however, seem to provide a consistent theory leading to an explanation of growth in its general course as well as in its specific peculiarities, to quantitative laws allowing calculation and prediction, and towards a unification of the great physiological realms of metabolism, growth and form development1.
TL;DR: It has never been clearly demonstrated step by step how the leafy thallus originated again, although some workers have succeeded in inducing further growth than others and made observations on which various theories have been based.
Abstract: SEVERAL investigators, including Janczewski1, Thuret and Bornet2, Berthold3 and more recently Okamura, Onda and Higashi4, have successfully germinated the carpospores of various species of Porphyra and obtained thereby filamentous growths. However, it has never been clearly demonstrated step by step how the leafy thallus originated again, although some workers have succeeded in inducing further growth than others and made observations on which various theories have been based. Grubb5 describes the liberation of the contents of the terminal cell of a short swollen filament as well as empty swollen tips of others. Both Kylin6 and Rees7,8 considered they saw evidence of the formation of monospores on the filaments, and it has been assumed that these germinated into the leafy thallus, although the possibility of such spores reproducing the filamentous stage cannot be ruled out. In Dangeard's9 view, the filamentous growth is protonemal, the leafy thallus developing on it as ‘buds'—a view contested by Rees7. At the other extreme, these filamentous growths from the carpospores have been considered pathological by Kunieda10, who asserts that the carpospores of the Japanese species, P. tenera Kjellmann, produced in the spring spend the summer in a resting condition. In the autumn, he considers they germinate direct into the leafy thallus, as do the monospores of all species which have been investigated. An earlier Japanese worker, Yendo11, described the liberation of ciliated micro- and macrogametes from the original spore as well as other swollen cells of the filamentous growths ; but it seems possible such spores belonged to an endophytic fungus.
TL;DR: Another type of reactivation of ultra-violet irradiated phage, namely, reactivation upon exposure to visible light in the presence of bacterial cells (photo-reactivation), is observed.
Abstract: COLI-BACTERIOPHAGE of the 'T' group1 are inactivated at a logarithmic rate by ultra-violet light. Some of these phages can be reactivated inside bacteria that adsorb more than one inactive phage particle2. I recently observed another type of reactivation of ultra-violet irradiated phage, namely, reactivation upon exposure to visible light in the presence of bacterial cells (photo-reactivation). Since this phenomenon may cause serious misinterpretations of results obtained in working with irradiated phage, it may be useful to report it at this early stage of its investigation.
TL;DR: In studies on unsaturated ketones, it is found that chalkone, flavanones, flavone and some of their derivatives, for example, buteine (2,4,3′,4′-tetrahydroxychalkone) showed a marked inhibition of the growth of Staph.
Abstract: INVESTIGATIONS by A. R. Todd1, H. Rinderknecht2, W. B. Geiger3 and others have shown that many unsaturated ketones with the grouping —C = C—CO—, also present in a number of naturally occurring antibiotics, possess antibacterial action. In our studies on unsaturated ketones, we found that chalkone, flavanone, flavone and some of their derivatives, for example, buteine (2,4,3',4'-tetrahydroxychalkone). a substance of vegetable origin, showed a marked inhibition of the growth of Staph. aureus. Also extracts of plants containing flavanones, flavones or flavonoles were found to be bacteriostatic4. Furthermore, we have prepared a number of synthetic chalkones of which some compounds suppressed the growth at high dilutions.
TL;DR: In the cytological changes which these compounds produce they largely resemble their aliphatic analogues, and the structures of these compounds may be taken as typical.
Abstract: IN a recent publication1 attention was directed to the cytotoxic action of a series of halogenoalkylarylanies, of which the compound PhN(CH2CH2Cl)2 may be taken as typical. The structural conditions requisite for activity were stated to be the presence of two halogenoalkyl groups in the molecule together with a certain minimum reactivity of the halogen, as measured by the ease of hydrolysis. In the cytological changes which these compounds produce they largely resemble their aliphatic analogues.