scholarly journals The variation of the dielectric constants of some organic liquids with frequency in the range 1 to 10 3 Kilocycles

1930 ◽  
Vol 126 (801) ◽  
pp. 213-230 ◽  
Keyword(s):  
Dielectric Constant ◽  
Extreme Values ◽  
Dielectric Constants ◽  
Organic Liquids ◽  
Frequency Range ◽  
Absolute Value ◽  
The Subject ◽  
The Mean ◽  
Made In

Whilst it is recognised that the dielectric constant of liquids changes in the frequency range 10 4 - 10 5 kilocycles per second in accordance with the theory of Debye, no systematic examination of the variation of the dielectric constant of simple liquids with frequency appears to have been made at frequencies below 10 3 kc. per second. Exception must be made of the work of Fricke* who showed that the dielectric constant of blood did not change in the range 0­­­­.8 to 4500 kc., and of that of Bryan who recorded no change in the constant for xylene and an increase in the constant for nitrobenzene in the range 200 to1200 kc. In the case of chloroform and benzene a number of independent determinations have been made, eachat a fixed frequency. The values of the constants, however, at frequencies less than 1000kc. fluctuate considerably, for benzene the divergence between the extreme values is about 2­­·0 percent, of the mean, for chloroform about 12­­·5 percent. It is of importance, therefore, to establish whether these fluctuations are due to experimental error or the variation of the constant with frequency. The experiments now described were planned preliminary to work at higher frequencies; measurements of the dielectric constant and of the conductivity of a number of liquids have been made in the frequency range 1 to 10 3 kc. Attention has been directed to examine the variation of these quantities with frequency rather than to obtain­ing their absolute values. Owing to the illness of one of the authors the work had to be discontinued before the original programme had been completed, nevertheless, in view of the increasing importance of the subject the results appear to be of sufficient interest to merit publication. Since the data now reported were obtained, an extremely careful determination of the absolute value of the dielectric constant for benzene at 1000 cycles has been described by Hartshorn and Oliver ( loc. cit. ). They report no change in the constant in the audio frequency range, that is, presumably, below 5 kc., and thus confirm, in part, the data now presented.

scholarly journals On the measurement of the dielectric constants of liquids, with a determination of the dielectric constant of benzene

1929 ◽  
Vol 123 (792) ◽  
pp. 664-685 ◽  
Keyword(s):  
Dielectric Constant ◽  
Physical Properties ◽  
Dielectric Constants ◽  
Experimental Conditions ◽  
The Past ◽  
A Value ◽  
The Subject ◽  
Important Indication

It has long been recognised that the dielectric constant of a substance gives an important indication of its constitution, and the classical papers of Nernst and Drude giving methods for the determination of dielectric constants, have been followed by a long series of papers giving the dielectric constants of several hundreds of pure liquids and solutions. Since the publication of Debye’s dipole theory in 1912, the literature of the subject has become even more voluminous than before. In surveying the mass of data one is struck by the very large discrepancies which exist in the values obtained by different observers for any one substance, and it is very difficult to decide whether they are due to the difficulty of pre­paring and purifying the substance, differences in experimental conditions such as frequency of the applied E. M. F., or errors in the methods of measure­ment. In order to make it possible to compare the results of different observers, and to provide a fundamental basis for new measurements, it is important that the value of at least one standard liquid should be known with unquestion­able accuracy. The object of the present investigation was to provide such a value. Benzene was chosen as the standard liquid since it has been very widely used in the past, and it is used as a standard in the measurement of other physical properties.

scholarly journals pH of exudate test in the physiological quality of crambe seeds

2016 ◽  
Vol 46 (6) ◽  
pp. 1014-1018 ◽  
Author(s):  
Charline Zaratin Alves ◽  
Lennis Afraire Rodrigues ◽  
Carlos Henrique Queiroz Rego ◽  
Josué Bispo da Silva
Keyword(s):  
Pearson Correlation ◽  
Raw Material ◽  
Mean Values ◽  
Tukey Test ◽  
Physiological Quality ◽  
The Subject ◽  
The Mean ◽  
C 30

ABSTRACT: Crambe is a rapeseed with high oil content and can be used as a winter cover or as a source of raw material for the production of biodiesel, however espite the growing interest in the culture, research on the subject is still incipient, especially concerning the seed production and analysis technology. The purpose of this study is to evaluate the physiological quality of crambe seeds, 'FMS Brilhante' cultivar, by testing the pH of exudate. Five seed lots were submitted to the determination of water content and the tests of germination and vigor (first count, emergence and tetrazolium). In the conduction of pH exudate test, temperatures (25 and 30oC), and periods of seed imbibition in water (15, 30 and 45 minutes) were tested. The experiment was conducted in a completely randomized manner, with four replicates, and the mean values were compared by the Tukey test at 5% probability; Pearson correlation between the pH of the exudate and initial tests was also made. Testing the pH of exudate is promising for separating lots of crambe seeds and the following combinations of 25°C/30 minutes or 30°C/45 minutes can be used.

scholarly journals Determination of trace elements in the plants of Mt. Bozdag, Izmir, Turkey

2010 ◽  
Vol 62 (3) ◽  
pp. 731-738 ◽  
Author(s):  
D. Yildiz ◽  
I. Kula ◽  
G. Ay ◽  
S. Baslar ◽  
Y. Dogan
Keyword(s):  
Trace Elements ◽  
Woody Plants ◽  
Statistical Significance ◽  
Absorption Spectrometry ◽  
Dry Weight ◽  
Current Level ◽  
The Mean ◽  
Herbaceous And Woody Plants ◽  
Made In

The aim of this study was to determine the current level of atmospheric heavy metal content on the Bozdag Mountain of the Aegean Region, Turkey. Twenty nine different plants were selected to study their potential as biomonitors of trace elements such as Ni, Zn, Fe, Pb, Mn and Cd (?g g-1, dry weight). The samples were collected from two different altitudes of Mt. Bozdag. The concentrations of trace elements were determined by atomic absorption spectrometry. The mean concentrations determined at 1000 m altitude ranged from 0.025 to 1.609, 0.232 to 0.731, 0.578 to 5.983, 0.287 to 0.565 and 0.176 to 2.659 (?g g-1, dry weight), for Ni, Zn, Fe, Pb and Mn, respectively. At the altitude of 1600 m, the values ranged from 0.023 to 0.939, 0.258 to 1.254, 0.839 to 5.176, 0.301 to 1.341 and 0.405 to 3.351 (?g g-1, dry weight) for Ni, Zn, Fe, Pb and Mn, respectively. No Cd was detected at either altitude. Statistical significance was determined by the independent sample t-test and comparisons were made in order to determine if there were any differences between the averages of herbaceous and woody plants. .

scholarly journals I. On the absolute expansion of mercury

1912 ◽  
Vol 211 (471-483) ◽  
pp. 1-32 ◽  
Keyword(s):  
Hydrostatic Method ◽  
Physical Problems ◽  
Glass Bulb ◽  
Different Temperatures ◽  
The Mean ◽  
The Absolute ◽  
Made In

The determination of the expansion of mercury by the absolute or hydrostatic method of balancing two vertical columns maintained at different temperatures does not appear to have been seriously attempted since the time of Regnault (‘Mém. de l’Acad. Roy. des Sci. de l’Institut de France,' tome I., Paris, 1847). His results, though doubtless as perfect as the methods and apparatus available in his time would permit, left a much greater margin of uncertainty than is admissible at the present time in many cases to which they have been applied. The order of uncertainty may be illustrated by comparing the value of the fundamental coefficient of expansion (the mean coefficient between 0° and 100°C.) given by Regnault himself, with the values since deduced from his observations by Wüllner and by Broch. They are as follows:— Regnault . . . . . . 0·00018153. Wüllner . . . . . . 0·00018253. Broch . . . . . . . 0·00018216. The discrepancy amounts to 1 in 180 even at this temperature, and would be equivalent to an uncertainty of about 4 per cent, in the expansion of a glass bulb determined with mercury by the weight thermometer method. The uncertainty of the mean coefficient is naturally greater at higher temperatures. If, in place of the mean coefficient, we take the actual coefficient at any temperature, the various reductions of Regnault’s work are still more discordant, and the rate of variation of the coefficient with temperature, which is nearly as important as the value of the mean coefficient itself in certain physical problems, becomes so uncertain that the discrepancies often exceed the value of the correction sought. It is only fair to Regnault to say that these discrepancies arise to some extent from the various assumptions made in reducing his results, and are not altogether inherent in the observations themselves.

Experiments on spirodistichous shoot apices. I

1951 ◽  
Vol 235 (624) ◽  
pp. 131-162 ◽  
Keyword(s):  
Lupinus Albus ◽  
Spiral Growth ◽  
Divergence Angle ◽  
Filling Process ◽  
Space Filling ◽  
Stem Apex ◽  
The Mean ◽  
Good Support ◽  
Made In

The shoot apex of Rhoeo discolor , a spirodistichous species, is described in detail. The mean divergence angle between successive leaf centres is 152°-6. Each new leaf covers only a small arc when first visible, and its flanks then extend round the apex until they meet in the later part of the plastochron. The new leaf is asymmetric, its half which is anodic in the direction of the genetic spiral being the shorter transversely and covering a mean arc of 166°-5 when the flanks meet. Thus the centre of a new leaf does not lie directly over the meeting-point of the flanks of the previous leaf, but above its anodic half. Experiments were made in order to discover the causes on which the divergence angle depends. As a preliminary some stem apices of Rhoeo were exposed and marked with transverse streaks of albumen and charcoal. But after several days the streaks had not been bent by the growth of the apex in the way which would be expected on Hirmer’s theory of spiral growth. In the main experiments the central part of P 1 , the youngest leaf, was cut out completely. It was necessary first to cut down P 2 and the older leaves of the bud nearly to their bases. The main results were that I 1 , the next leaf to arise, was displaced towards the missing centre of P 1 and that the angle I 1 — I 2 was larger than the normal, and sometimes exceeded 180° (see figure 6). In some other experiments the central part of P 2 was removed as well as that of P 1 In these also the angle I 1 — I 2 increased, and in one of them the genetic spiral reversed permanently, but the displacement of I 1 towards P 1 was usually less. It is concluded that the position of the centre of each new leaf depends on a balance between inhibiting influences exerted on the stem apex by existing leaf centres. The position of a new leaf n depends mainly on the inhibitions coming from the centres of the two youngest leaves, n -1 and n —2, and to a lesser degree on those from the centres of n —3 and possibly n -4. The strength of the inhibition thus decreases with the age of the leaf from which it comes and also with the distance from the inhibiting centre. The asymmetries of the leaves that arose after the operations are reported and discussed in comparison with those of the normal leaves. Many of the facts can be explained if it is supposed that the same influences from existing leaves which tend to inhibit the formation of leaf centres promote the extension of leaf flanks round the apex. But the asymmetry of I 3 in most of the experiments is at present not explained on this hypothesis. The localization and determination of leaves in Rhoeo is further discussed and compared with the corresponding processes in Lupinus albus and other dicotyledons. It is concluded that in spirodistichous monocotyledons the localization of leaves, depending on physiological inhibitions, is different from what it is in dicotyledons, in which it was previously concluded to be a space-filling process. The process of determination is also shown to be different in Rhoeo , since a rather small central part of a leaf is determined first, and from it the determination extends by induction round the apex. In both these respects the experiments on Rhoeo , unlike those on dicotyledons, give good support to Richards’s theory of phyllotaxis, which, however, was intended to apply to all groups.

scholarly journals On the direct determination of the electrostatic moments of molecules

1929 ◽  
Vol 124 (795) ◽  
pp. 689-698 ◽  
Keyword(s):  
Dielectric Constant ◽  
Direct Determination ◽  
Negative Temperature ◽  
Dielectric Constants ◽  
Temperature Coefficients ◽  
Different Temperatures

According to Faraday's ideas, the specific inductive capacity of a substance is due to the polarisation of the molecules as wholes. This is the basis of the old Clausius-Mosotti theory of dielectrics, on which it is shown first that the polarisation P is proportional to the polarising field, i. e. , P = k E, k being the dielectric constant, and second that δ being the density of the dielectric, k - 2/ k + 2 ·1/δ = constant. Now it is known that some substances have large negative temperature coefficients for their dielectric constants which cannot thus be accounted for. To provide for this Debye proposed the theory that the molecules were permanently polarised and that they were systematically orientated in the field. This leads to the equation k - 2/ k + 2 = a T -1 + b T -2 , to represent the change of specific inductive capacity with temperature. This theory has been developed by Gans and others, and a number of measurements have been made by Smyth and others, who have found the molecular moments of many substances by measuring the dielectric constants at different temperatures.

Dielectric constant measurements of thin films and liquids using terahertz metamaterials

RSC Advances ◽  
2016 ◽  
Vol 6 (73) ◽  
pp. 69381-69386 ◽  
Author(s):  
S. J. Park ◽  
S. A. N. Yoon ◽  
Y. H. Ahn
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Polymer Films ◽  
Dielectric Constants ◽  
Polar Liquids ◽  
Terahertz Metamaterials

In this paper, we demonstrate that terahertz (THz) metamaterials are powerful tools for determination of dielectric constants of polymer films and polar liquids.

DETERMINATION OF DIELECTRIC CONSTANT IN BINARY ORGANIC SYSTEMS

1960 ◽  
Vol 38 (9) ◽  
pp. 1606-1616 ◽  
Author(s):  
C. G. Miller ◽  
O. Maass
Keyword(s):  
Binary Systems ◽  
Isopropyl Alcohol ◽  
Dielectric Constants ◽  
Empirical Equations ◽  
Absolute Accuracy ◽  
Accurate Data ◽  
Organic Systems ◽  
Benzene Toluene ◽  
Made In

Measurements of the dielectric constants of binary systems have been made; hexane, benzene, toluene, acetone, isopropyl alcohol, and nitrobenzene have been used two at a time. It was the purpose to obtain accurate data for the dielectric constants for the 15 systems over the whole range of concentrations from 0 to 100%, with the absolute accuracy of 0.1%. It is claimed that the relative accuracy is of this order. From the data obtained regularities have been found which are expressed in the form of empirical equations which summarize the data. Tentative suggestions regarding theoretical conclusions are made in a number of cases.

EVALUATION OF THE DOUBLE ANTIBODY RADIOIMMUNOASSAY OF INSULIN AND THE DETERMINATION OF INSULIN IN PLASMA AND URINE IN NORMAL SUBJECTS

1969 ◽  
Vol 60 (2) ◽  
pp. 327-351 ◽  
Author(s):  
Kai R. Jørgensen
Keyword(s):  
Extreme Values ◽  
Degradation Products ◽  
Insulin Response ◽  
Normal Subjects ◽  
Precipitation Reaction ◽  
Fasting Insulin ◽  
Double Antibody ◽  
Insulin In Plasma ◽  
The Subject

ABSTRACT The use of the double antibody method for radio-immunological determination of insulin in plasma was evaluated on the basis of dilution and recovery experiments, as well as by the investigation of the reproducibility and accuracy of the method. Given the optimum conditions for the precipitation reaction, the method appears from the present investigations to be well suited for plasma insulin determinations. With the technique used for the separation of free and antibody bound insulin, the results of the insulin determination were found to be independent of the radioactive degradation products present in the tracer insulin. It was not possible to demonstrate any increased degradation of the tracer insulin by incubation in plasma or urine as compared with incubation in 0.5 % human albumin buffer. The absolute insulin values were found to be independent of the length of the incubation period. No difference was found between the fasting insulin concentrations in a group of new-born infants of non-diabetic mothers and a group of adult normal subjects. Similarly, the fasting insulin values were found to be independent of the sex of the subject investigated. After oral administration of glucose a considerable variation was found in the insulin response in a group of normal subjects. This variation, within the weight limits used, was found to be independent of the sex, age and weight of the subject investigated. A corresponding condition was found to be valid for the insulin excretion in the urine of normal subjects. It was concluded that the large variation in the insulin response in a group of normal subjects did not allow conclusions about the clinical significance of the extreme values, but that the variation alone must be taken as an expression for a pronounced biological variation.

V. Experimental determination of the velocity of white and of coloured light

1882 ◽  
Vol 173 ◽  
pp. 231-289 ◽  
Keyword(s):  
Experimental Determination ◽  
Late Professor ◽  
Velocity Of Light ◽  
Accurate Knowledge ◽  
Number Of Teeth ◽  
Propagation Of Light ◽  
The Mean ◽  
Electro Magnetic ◽  
Made In

It is remarkable that, although the importance of an accurate knowledge of the velocity of light has been very generally appreciated, no attempt has hitherto been made in this country to measure that velocity by experiment. Our own experiments date from many years back, but we have been prevented by various interruptions to our work from giving a result which could lay claim to the greatest accuracy. In 1878 we made at Pitlochry, in Perthshire, between 600 and 700 observations, but the toothed wheel which was made for us not having the number of teeth in it which we had ordered, we were not able to eliminate perfectly certain unknown quantities occurring in the formulæ, and we felt that it would be better to wait until we could give a result in which we had perfect confidence. At the same time we resolved so to alter our apparatus that we should not have to depend upon the mean of a very large number of experiments to give us a good result, but that each observation should give us an accurate measurement, free from all doubt. This has now been accomplished by the experiments conducted in 1880-81 between Kelly House, Wemyss Bay, and the hills behind Innellan, across the mouth of the River Clyde. The chief importance of a determination of the velocity of light is that it gives us the means, considered by many to be the best means, of determining the solar parallax, by combining the result with the constant of aberration determined by astronomers. The investigation has also acquired a further interest from the speculations of the late Professor Clerk Maxwell, according to which the propagation of light is an electro-magnetic phenomenon, and its velocity should be the same as that of the propagation of an electro-magnetic displacement.

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