Showing papers in "Nature in 1951"
TL;DR: Preliminary experiments showed that the anthrone and the α-naphthol sulphonate reagents give good results with pure sugar solutions, but the presence of only traces of solvents such as butanol, phenol and propionic acid used in the chromatographic separation of the sugars rendered them useless.
Abstract: VOLUMETRIC procedures have been used for the quantitative determination of sugars after separation by partition chromatography1,2. It has been our experience that these methods not only require considerable skill, but also they are lengthy and sensitive to slight variation of the conditions. We have therefore attempted to develop a simple quantitative colorimetric procedure. Preliminary experiments showed that the anthrone3 and the α-naphthol sulphonate4 reagents give good results with pure sugar solutions, but the presence of only traces of solvents such as butanol, phenol and propionic acid used in the chromatographic separation of the sugars rendered them useless.
1,770 citations
TL;DR: In this article, the reaction of Grignard reagents with anhydrous ferric chloride was studied, but no definite evidence for organo-iron compounds was found in such reactions.
Abstract: NUMEROUS investigators have studied the reaction of Grignard reagents with anhydrous ferric chloride, but have failed to isolate any organo-iron compounds or to produce any definite evidence for their formation in such reactions.
1,420 citations
TL;DR: The following experiment demonstrates that such a period of time in the female tract is required for the spermatozoa to acquire their fertilizing capacity.
Abstract: IN the natural sequence of mammalian fertilization, the spermatozoa await the arrival of ova in the Fallopian tubes. The time of waiting may vary from 6 hr. (rabbit), 24 hr. (ferret), 20–30 hr. (pig, sheep and cattle) up to perhaps several months (bat)1. Since the transportation of sperm from the vagina to the upper part of the tube is very rapid (a few minutes to 6 hr.1), and since the number of spermatozoa present at the site of fertilization is very small1, this time interval is not necessarily for the accumulation of a large number of spermatozoa to ensure fertilization. The following experiment demonstrates that such a period of time in the female tract is required for the spermatozoa to acquire their fertilizing capacity.
1,406 citations
TL;DR: In this article, Sommerfeld presents a review of the theoretic aspects of Physik, including Mechanik, Elektrodynamik and Partielle Differentialgleichungen der Physik.
Abstract: Vorlesungen uber theoretische Physik Von Prof. Arnold Sommerfeld. Band 1: Mechanik. Vierte, neubearbeitete Auflage. Pp. xii + 276. 18 D. marks. Band 2: Mechanik der deformierbaren Medien. Pp. xv + 376 + 4 plates. 18 D. marks. Band 3: Elektrodynamik. Pp. xvi + 368. 18 D. marks. Band 6: Partielle Differentialgleichungen der Physik. Pp. xiii + 332. 18 D. marks. (Wiesbaden: Dieterich'sche Verlagsbuchhandlung, 1947–1949.)
669 citations
TL;DR: In this article, the absolute configuration of Optically Active Compounds by means of X-Rays was determined by determination of the absolute position of the X-ray reflectors of the active compounds.
Abstract: Determination of the Absolute Configuration of Optically Active Compounds by Means of X-Rays
595 citations
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TL;DR: Blood Groups in Man, by Dr. R. R Race and Dr. Ruth Sanger, 1950 is published.
Abstract: Blood Groups in Man By Dr. R. R. Race and Dr. Ruth Sanger. Pp. xv + 290. (Oxford: Blackwell Scientific Publications, Ltd., 1950.) 30s. net.
534 citations
TL;DR: The 21-cm line was discovered by Ewen and Purcell as discussed by the authors, who had seen the signal months before, but waited for corroboration by Dutch and Australian astronomers before publishing: Muller and Oort's paper [Muller, C. A. & Oort, J. H.
Abstract: In September 1951 Ewen and Purcell reported in Nature of the discovery of the hydrogen 21-cm line. In fact, they had seen the signal months before, but waited for corroboration by Dutch and Australian astronomers before publishing: Muller and Oort’s paper [Muller, C. A. & Oort, J. H. Nature 168, 357–358 (1951)] in the pages following Ewen and Purcell's report includes the text of a cable sent by Pawsey from Australia. Oort had already realized the significance of the discovery - that detection of this spectral line, produced by transitions between hyperfine levels of the ground-state hydrogen atom, would permit measurements of velocities by the Doppler effect. The 21-cm line put radioastronomy on the map, and brought about a revolution in the study of galactic structure.
A Study of Recent Views of its Causes. By G. S. Carter. Pp. xv + 368. (London: Sidgwick and Jackson, Ltd., 1951.) 30s. net.
304 citations
TL;DR: New X-Ray Evidence on the Configuration of Polypeptide Chains: Polypeptic Chains in Poly-γ-benzyl-L-glutamate, Keratin and Haemoglobin is presented.
Abstract: New X-Ray Evidence on the Configuration of Polypeptide Chains: Polypeptide Chains in Poly-γ-benzyl-L-glutamate, Keratin and Haemoglobin
274 citations
TL;DR: The experiments described below indicate that intact 5′ nucleotides can be isolated from enzymatically hydrolysed calf liver ribonucleic acid.
Abstract: THOUGH the manner in which the four nucleotides of ribonucleic acid are combined in the intact molecule is not completely settled, the data obtained from analyses of the chemical degradation products are most compatible with phosphoryl-group attachments through the C2 and C3 positions of the ribose group1. The exclusion of C5 phosphoryl linkages rests principally upon the failure to isolate 5′ nucleotides or the acid-stable ribose-5-phosphate from acid hydrolysates of ribonucleic acid. However, Gulland and Jackson2, hydrolysing yeast ribonucleic acid with a snake venom containing a phosphodiesterase and a specific 5′ nucleotidase, found 35 per cent of the total phosphate liberated as inorganic phosphate, suggesting that a large number of the phosphoryl groups were attached to the ribose C5 position. Recently, Schmidt3, utilizing periodate titrations of ribonuclease-hydrolysed yeast ribonucleic acid, concluded that some nucleotide groups had been linked to positions other than ribose C2 or C3 in the original ribonucleic acid. The experiments described below indicate that intact 5′ nucleotides can be isolated from enzymatically hydrolysed calf liver ribonucleic acid.
253 citations
TL;DR: Fundamentals were presented and it was shown by adapting the equations of Lagrange that in certain systems the part played by energy in linear systems is played by areas under a curve in the case of non-linear systems.
Abstract: fundamentals, and showed by adapting the equations of Lagrange that in certain systems the part played by energy in linear systems is played by areas under a curve in the case of non-linear systems. Manual control as distinct from automatic control was not forgotten. The paper on this subject by J. D. North included a thorough analysis of a 'model' that may provide a useful approximation for the response of hand to eye in some simple situations such as target tracking or car driving. The discussions throughout the conference were vigorous and sustained. It appeared to be the opinion of all who attended that the conference has helped to lay foundations on which much further progress may now be based. The papers presented, together with selected material from the discussions during the conference, will be published in due course as a single volume by Butterworths Scientific Publications, Ltd. A. TUSTIN
248 citations
TL;DR: The Theory of Atomic Collisions By N. F. Mott and H. S. Massey as mentioned in this paper, Second edition. Pp. xv + 388. 35s. net.
Abstract: The Theory of Atomic Collisions By N. F. Mott and H. S. W. Massey. (International Series of Monographs on Physics.) Second edition. Pp. xv + 388. (Oxford: Clarendon Press; London: Oxford University Press, 1949.) 35s. net.
TL;DR: Ito et al. as mentioned in this paper published a collection of papers concerning submicroscopic twinning in crystals, with appendices, in collaboration with R. Sadanaga and Y. Takeuchi.
Abstract: X-Ray Studies on Polymorphism Being a Collection of Papers concerning Submicroscopic Twinning in Crystals, with Appendices. By Prof. T. Ito, in collaboration with R. Sadanaga and Y. Takeuchi. Pp. vii + 231. (Tokyo: Maruzen Co., Ltd., 1950.) 10 dollars.
TL;DR: Under optimum conditions, bursting of well over 90 per cent of the cells is easily attained, and the only substance introduced is a gas which has been shown to be non-injurious to the bacteria.
Abstract: MANY investigations of bacterial metabolism require that the contents of the cell be released. This apparently simple requirement has not yet been met in a completely satisfactory way. The present method differs in principle from previous techniques. It consists of sudden release of applied gas pressure and is very simple, rapid and inexpensive. Under optimum conditions, bursting of well over 90 per cent of the cells is easily attained, and the only substance introduced is a gas which has been shown to be non-injurious to the bacteria.
TL;DR: This action of thrombin, which tentatively may be considered as a very specific proteolysis, was discovered independently in Cambridge and in Leeds, and for this reason the relevant observations are reported jointly.
Abstract: IN spite of much literature on the clotting of blood, the exact mechanism of the final event, the mode of transformation of soluble fibrinogen to insoluble fibrin by the action of thrombin, remains unknown. The concept of thrombin as a hydrolytic or proteolytic enzyme1,2 has fallen into disfavour3, and in recent years other plausible but unproved mechanisms have been proposed4–6. In a study7 of the proteins of the keratin–myosin–fibrinogen group by end-group assay with fluorodinitrobenzene8, only small amounts of terminal amino-groups could be detected in fibrinogen, although the amounts were not sufficiently small to conclude, as in the case of myosin and tropomyosin, that the molecule is constructed of cyclo-peptide units. The action of purified thrombin, however, results consistently in the appearance of amino-terminal residues of glycine, and whatever the ensuing mechanism, we believe that the fundamental enzymic step in the transformation of fibrinogen to fibrin is associated first with the appearance of these groups. This action of thrombin, which tentatively may be considered as a very specific proteolysis, was discovered independently in Cambridge and in Leeds, and for this reason the relevant observations are reported jointly.
TL;DR: The increased staining propensity of dead cells may be used to obtain a quantitative estimate of the proportions of live and dead spermatozoa in freshly ejaculated ram semen, and a technique of staining with Opal Blue and Eosin is described which employs this principle.
Abstract: Lasley, Easley and McKenzie1 have shown that the increased staining propensity of dead cells may be used to obtain a quantitative estimate of the proportions of live and dead spermatozoa in freshly ejaculated ram semen, and have described a technique of staining with Opal Blue and Eosin which employs this principle. They have also emphasized that the imposition of temperature-shock on test ejaculates by sudden cooling is accompanied by an increase in the proportion of stained spermatozoa. In their studies, shock effects due to differences of temperature between semen and stain at the time of mixing were rigidly excluded, and no subsequent attempt has apparently been made to determine the critical level at which such temperature effects may be encountered, or to express in quantitative terms the degree of shock encountered at different temperature-levels.
TL;DR: Results from experimental treatments of the shoot apex of the potato, Solanum tuberosum, shed new light on this phenomenon of which the mechanism is but little understood.
Abstract: IN flowering plants, a leaf primordium may be initially centric in shape1; but on further growth it becomes dorsiventral, a phenomenon of which the mechanism is but little understood. Results from experimental treatments of the shoot apex of the potato, Solanum tuberosum, shed new light on this phenomenon. The leaves arise in spiral sequence, with an average divergence angle of 138°. Primordia visible at the time of the operation will be called P1 and P2; P1 being the younger. The first leaf to arise after the operation, but initially invisible, will be called I1.
TL;DR: The substance known as maleic hydrazide (1,2-dihydropyridazine-3,6-dione) was introduced in 1949 by the United States Rubber Co. as a “growth regulator” with practical value in enhancing winter hardiness, delaying flowering, inducing male sterility, and also in controlling weeds.
Abstract: THE substance known as maleic hydrazide (1,2-dihydropyridazine-3,6-dione) was introduced in 1949 by the United States Rubber Co. as a “growth regulator”. In the past year it has been widely tested in laboratory and field experiments1,2. Its practical value in enhancing winter hardiness, delaying flowering, inducing male sterility, and also in controlling weeds has been described3. Its growth-restricting effects consist of destroying the apical dominance of shoots, stopping root growth, and destroying germ cells4.
TL;DR: Observation of Gymnarchus niloticus in an aquarium has revealed a mode of locomotion through waves passing over the extended dorsal fin and executed forwards and backwards with equal ease, and a marked ability of the fish to avoid obstacles while swimming backwards.
Abstract: THROUGH the kindness of Dr. K. R. S. Morris, Gold Coast, I received a living specimen of Gymnarchus niloticus, a fish which occurs in the rivers of West Africa and in the Nile. Observation of this fish in an aquarium has revealed two striking features: (i) a mode of locomotion through waves passing over the extended dorsal fin and executed forwards and backwards with equal ease; (ii) a marked ability of the fish to avoid obstacles while swimming backwards. The hind end and particularly the finger-like tail are known to contain tissues corresponding to an electric organ; it seemed of interest to consider whether this organ may enable the animal to detect objects in the vicinity of its body.
TL;DR: The ninhydrin reaction has been used almost exclusively for the identification and quantitative assay of amino-acids, and its rapid fading on filter-paper chromatograms makes it difficult to construct permanent or semi-permanent reference maps from which not only the type, but also the approximate quantity of the unknown mixture, can be deduced.
Abstract: IN filter-paper partition chromatography, the ninhydrin reaction has been used almost exclusively for the identification and quantitative assay of amino-acids. One of the chief disadvantages of the blue pigment formed in this reaction is its rapid fading on filter-paper chromatograms. This makes it difficult to construct permanent or semi-permanent reference maps from which not only the type of amino-acid, but also the approximate quantity of the unknown mixture, can be deduced.
TL;DR: It is shown that proguanil has no action on in vitro cultures of the exo-erythrocytic forms of Plasmodium gallinaceum or on the blood forms of P. cynomolgi, whereas, under similar conditions, serum from animals dosed with the drug has high antimalarial activity.
Abstract: SINCE the discovery of ‘Paludrine’ (proguanil, N1-p-chlorophenyl-N5-isopropyldiguanide) by Curd, Davey and Rose1, considerable evidence has accumulated that this drug probably differs in its mode of action from most other antimalarials. Direct evidence that proguanil is transformed in the animal body into another, more active, compound was provided by Hawking2 and Hawking and Perry3, who showed that proguanil has no action on in vitro cultures of the exo-erythrocytic forms of Plasmodium gallinaceum or on the blood forms of P. cynomolgi, whereas, under similar conditions, serum from animals dosed with the drug has high antimalarial activity.
TL;DR: Theoretically, it is possible to scan the image or its photograph mechanically; but this has seldom been done in practice; the whole method of obtaining resolution by lenses involves so much loss of light, lack of control of contrast, and other difficulties, that it is difficult to provide a good display or method of scanning.
Abstract: SURPRISINGLY little of the information obtained with microscopes has been quantitative; most observers are content to sit at the microscope and regard the image, or to photograph it. Theoretically, it is possible to scan the image or its photograph mechanically; but this has seldom been done in practice. The whole method of obtaining resolution by lenses involves so much loss of light, lack of control of contrast, and other difficulties, that it is difficult to provide a good display or method of scanning.
TL;DR: The volume changes which accompany the disappearance of the latter in a muscle fibre suspension are being studied in an attempt to extend observations on the synæresis of actomyosin by adenosine triphosphate to a less disorganized and more physiologically complete system.
Abstract: IN an attempt to extend observations on the synaeresis of actomyosin by adenosine triphosphate to a less disorganized and more physiologically complete system, the volume changes which accompany the disappearance of the latter in a muscle fibre suspension are being studied. Small (2-gm.) samples of fresh rabbit psoas muscle are broken up in isotonic potassium chloride solution to particles of single-fibre diameter and approximately 1 mm. in length. This system has the advantage that, while a high degree of intrafibrillar organization is retained, such substances as salts, adenosine triphosphate and enzyme inhibitors are easily introduced and their effects on fibre-volume readily observed. The suspensions are spun in a centrifuge modified to permit continuous reading of the volume occupied by the fibres. Results so far obtained are here briefly summarized.
TL;DR: Partridge found reduced attack on the paper by the use of trichloracetic acid as acidifying agent, and reported improved spot definition with aniline hydrogen phthalate dissolved in butanol.
Abstract: PHENOLIC spraying reagents for the detection of sugars on paper chromatograms as introduced by Forsyth1, while greatly improving the selectivity of the method, had the disadvantages that the mineral acid attacked the paper, making it brittle when dried, and giving rise to dark background colours, and that the solvent caused diffusion of the sugar, with consequent poor definition of the spot boundary. Partridge2 found reduced attack on the paper by the use of trichloracetic acid as acidifying agent, and reported improved spot definition with aniline hydrogen phthalate dissolved in butanol3. Other agents proposed have included aniline hydrogen oxalate4, aniline – trichloracetic acid5, benzidine – acetic acid6, and ethanolic solutions of phenols and amines acidified with small amounts of hydrochloric acid7.
TL;DR: It has often been suggested that by far the greatest production of organic matter on earth is due to the marine plankton algæ, but investigations are, however, extremely scarce.
Abstract: IT has often been suggested that by far the greatest production of organic matter on earth is due to the marine plankton algae. Investigations are, however, extremely scarce. In some few areas the quantities of organic matter produced have been calculated by means of indirect methods, as, for example, from the decrease of nutrient salts or carbon dioxide during a definite period. The quantities calculated are, at best, minimum values for production, as account could be taken neither of the carbon dioxide absorbed from the atmosphere or produced by respiration of animals and bacteria, nor of the nutrient salts regenerated during the period and utilized again1.
TL;DR: In this paper, an observation of a line in the Galactic Radio Spectrum (GRS) at 1,420 Mc/sec., and an estimate of Galactic Rotation is presented.
Abstract: Observation of a Line in the Galactic Radio Spectrum: The Interstellar Hydrogen Line at 1,420 Mc./sec., and an Estimate of Galactic Rotation