scholarly journals III. On the determination, at sea, of the specific gravity of sea-water

1875 ◽  
Vol 23 (156-163) ◽  
pp. 301-308 ◽  
Keyword(s):  
Specific Gravity ◽  
Physical Condition ◽  
Sea Water ◽  
Accurate Determination ◽  
Actual Difference ◽  
Made In

In the investigation of the physical condition of the ocean the accurate determination of the specific gravity of the water holds a first place. The tolerably numerous observations which have been made in this direction, in a more or less connected manner, are sufficient to prove that the density of the water varies, not only with the latitude and longitude, but also with the distance from the surface of the source from which it is taken. This difference of density depends partly on an actual difference in saltness, and partly on a difference in temperature of the water.

scholarly journals Harnessing PET to track micro- and nanoplastics in vivo

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Outi Keinänen ◽  
Eric J. Dayts ◽  
Cindy Rodriguez ◽  
Samantha M. Sarrett ◽  
James M. Brennan ◽  
...  
Keyword(s):  
Sea Water ◽  
Accurate Determination ◽  
Nuclear Imaging ◽  
Imaging Data ◽  
Biodistribution Studies ◽  
Positron Emission ◽  
20 Nm ◽  
Pharmacokinetic Behavior

AbstractThe proliferation of plastics in the environment continues at an alarming rate. Plastic particles have been found to be persistent and ubiquitous pollutants in a variety of environments, including sea water, fresh water, soil, and air. In light of this phenomenon, the scientific and medical communities have become increasingly wary of the dangers posed to human health by chronic exposure to microplastics (< 5 mm diameter) and nanoplastics (< 100 nm diameter). A critical component of the study of the health effects of these pollutants is the accurate determination of their pharmacokinetic behavior in vivo. Herein, we report the first use of molecular imaging to track polystyrene (PS) micro- and nanoplastic particles in mammals. To this end, we have modified PS particles of several sizes—diameters of 20 nm, 220 nm, 1 µm, and 6 µm—with the chelator desferrioxamine (DFO) and radiolabeled these DFO-bearing particles with the positron-emitting radiometal zirconium-89 (89Zr; t1/2 ~ 3.3 d). Subsequently, positron emission tomography (PET) was used to visualize the biodistribution of these radioplastics in C57BL/6J mice at 6, 12, 24, and 48 h after ingestion. The imaging data reveal that the majority of the radioplastics remain in the gastrointestinal tract and are eliminated through the feces by 48 h post-ingestion, a result reinforced by acute biodistribution studies. Ultimately, this work suggests that nuclear imaging—and PET in particular—can be a sensitive and effective tool in the urgent and rapidly growing effort to study the in vivo behavior and potential toxicity of micro- and nanoplastics.

A SIMPLE RAPID METHOD FOR DETERMINATION OF SPECIFIC GRAVITY OF SMALL SAMPLES OF URINE

PEDIATRICS ◽  
1959 ◽  
Vol 24 (5) ◽  
pp. 814-818
Author(s):  
Allen S. Goldman
Keyword(s):  
Specific Gravity ◽  
Present Report ◽  
Total Sample ◽  
Mineral Oil ◽  
Small Samples ◽  
Gradient System ◽  
Small Opening ◽  
Flotation Method ◽  
Made In

THE THERAPY of infants with disturbances in fluid balance is greatly assisted by knowledge of the specific gravity of the urine. Frequently only a few milliliters can be collected at any one time, while a minimum sample of 25 ml is necessary for use of the smallest urinometers currently available. The existing methods of determining specific gravity of one drop of urine are somewhat laborious, and require expensive equipment and the services of a relatively skilled technician. The present report describes a method which is rapid and simple and requires only a few drops of urine in its use. It is similar in principle to the determination of specific gravity of blood by the copper-sulfate method. For use with urine, mixtures are employed of two relatively nonvolatile liquids, immiscible with water, and with specific gravities nearly equally above and below the range in urine. The specific gravity of urine is determined by allowing one drop to fall into each of a series of tubes containing a mixture of the two liqquids made up to various specific gravities ranging from 1.005 to 1.030 (Fig. 1). That mixture in which the drop of urine comes most nearly to remaining still (neither rising nor falling after coming to rest) approximates the specific gravity of the urine. The total sample needed is only a few drops, which can be quite small if a dropper with a small opening (2 mm) is used. The determination takes a few minutes. A year's supply of the mixtures can be made in one afternoon and costs less than $6.00. MATERIALS The two solutions used were selected from the flotation method of Kirk, using a density gradient system. These are Liquid 1, dibutyl-n-phthalate (Eastman), specific gravity 1.04820°; and Liquid 2, kerosene, specific gravity 0.8220°. (Similar results were obtained by substituting California mineral oil, specific gravity 0.842-0.88420°, for kerosene.)

scholarly journals Discussion on the structure of atomic nuclei

1929 ◽  
Vol 123 (792) ◽  
pp. 373-390 ◽  
Keyword(s):  
Accurate Determination ◽  
Essential Point ◽  
Whole Numbers ◽  
Atomic Nuclei ◽  
Whole Number ◽  
Nuclear Atom ◽  
The Individual ◽  
The Masses ◽  
Made In

Sir Ernest Rutherford: It was on March 19, 1914, that the Royal Society held its last discussion on the constitution of the atom—just fifteen years ago. I had the honour to open the discussion on that occasion, and the other speakers were Mr. Moseley, Profs. Soddy, Nicholson, Hicks, Stanley Allen, S. P. Thomp­son. In my opening remarks I put forward the theory of the nuclear atom and the evidence in support of it, while Mr. Moseley gave an account of his X-ray investigations, which defined the atomic numbers of the elements, and showed how many gaps were present between hydrogen number 1 and uranium number 92. Prof. Soddy drew attention to the existence of isotopes in the radioactive series, and also to a remarkable observation by Sir Joseph Thomson and Dr. Aston, who had obtained two parabolas in the positive ray spectrograph of neon, and he suggested that possibly the ordinary elements might also consist of mixture of isotopes. I think you will find that the remarks and suggestions made in this discussion fifteen years ago have a certain pertinence to-day. In particular Hicks and Stanley Allen drew attention to the importance of taking into account the magnetic fields in the nucleus, although at that time we had very little evidence on that point, and even to-day our information is very scanty. What has been accomplished in the intervening period ? On looking back we see that three new methods of attack on this problem have been developed. The first, and in some respects the most important, has been the proof of the isotopic constitution of the ordinary elements, and the accurate determination of the masses or weights of the individual isotopes, mainly due to the work of Dr. Aston. This has led in a sense to an extension of the original ideas of Moseley. The experiments of the latter fixed the number of possible nuclear charges, while Aston has shown that there are a large number of species of atoms each defined by its nuclear charge, although their masses and their nuclear constitution may be different. The essential point brought out in the earlier work of Dr. Aston was that the masses of the elements are approxi­mately expressed by whole numbers, where oxygen is taken as 16—with the exception of hydrogen itself. But the real interest, as we now see it, is not the whole number rule itself, but rather the departures from it.

scholarly journals On a relation between the refractive and dispersive constants of the inert gases

1927 ◽  
Vol 114 (769) ◽  
pp. 659-661
Keyword(s):  
Accurate Determination ◽  
Inert Gases ◽  
Critical Temperatures ◽  
Philosophical Magazine ◽  
Empirical Relations ◽  
Five Elements ◽  
Made In

In 1911 I published in the ‘Philosophical Magazine’ a paper on new determinations of some constants of the inert gases, and drew attention to the remarkable empirical relations which subsist between (1) the calculated numbers of “dispersion” electrons in the atoms of these five elements, (2) their “viscosity diameters” as determined by Prof. A. O. Rankine, and (3) their critical temperatures. Since that time the figures used have undergone revision. The accurate determination of the value of ε by Millikan has enabled us to give absolute, instead of relative, values to the apparent numbers of dispersion electrons ( q , see Table I). Chapman has recalculated the viscosity diameters, and Rankine has revised Chapman’s values, in the light of corrections to be made in his own values of Sutherland’s constants for argon, krypton and xenon. But these alterations have not affected the validity of the relations then published.

scholarly journals Derivation of the Rotational Frequency of Massive Stars from Seismic Studies

2004 ◽  
Vol 215 ◽  
pp. 199-204 ◽  
Author(s):  
C. Aerts ◽  
R. Scuflaire ◽  
A. Thoul
Keyword(s):  
Main Sequence ◽  
High Spatial Resolution ◽  
Massive Stars ◽  
Accurate Determination ◽  
Rotation Frequency ◽  
Rotational Frequency ◽  
Current Status ◽  
B Stars ◽  
Made In

In this contribution we review the current status of the determination of the rotational frequency in non-radially pulsating B stars, i.e. β Cep stars and slowly pulsating B stars. Considerable progress is currently being made in the understanding of the non-radial oscillations of main-sequence B stars by means of high-temporal, high-spatial resolution spectroscopic time series. This has led to the detection of frequency multiplets, which are interpreted as rotationally splitted non-radial modes and which allow an accurate determination of the surface rotational frequency in some stars. We outline how our future goal, i.e. the derivation of the internal rotation frequency, can be achieved.

Preparation of U(VI) and Th(IV) alpha-sources from sea and fresh water samples by combining coprecipitation, solvent extraction and electrodeposition procedures

2004 ◽  
Vol 92 (3) ◽  
Author(s):  
R. Zarki ◽  
A. Elyahyaoui ◽  
A. Chiadli
Keyword(s):  
Solvent Extraction ◽  
Fresh Water ◽  
Water Samples ◽  
Sea Water ◽  
Accurate Determination ◽  
Simple Method ◽  
Considerable Saving ◽  
Initial Aqueous Solution ◽  
Initial Ph

SummaryA simple method combining coprecipitation, solvent extraction and electrodeposition for determining uranium and thorium in sea water and fresh water samples is developed. It offers a considerable saving in time, minimising chemical treatment and costs. The analytical procedure consists of enrichment of U and Th by coprecipitation with iron(III) hydroxides and subsequent extraction by diethylether solution and electrodeposition of each actinide in the extracting organic phase in which it was separated.The dependence of the coprecipitation, the extraction-electrodeposition and the overall yields of the above mentioned elements is examined in relation to the initial aqueous solution acidity and various amounts of iron carrier. At an initial pH between 6 and 10, quantitative coprecipitation of U and Th requires use of an Fe(III) quantity which depends on the acidity of these solutions. This quantity varies, under explored conditions, between 10 and 110mg/L. At a starting pH of 11, this coprecipitation becomes almost independent of Fe(III) amounts.The proposed procedure was used to analyse the content of U and Th isotopes in water samples. Recoveries of 60%-93% are obtained for uranium and 63%-86% for thorium. Good resolutions (37-56.5keV) are also achieved under optimum conditions. These resolutions allow to make accurate determination of U and Th isotopes in various water samples.

scholarly journals II. Magnetic survey of the east of France in 1869

1872 ◽  
Vol 162 ◽  
pp. 7-27
Keyword(s):  
Accurate Determination ◽  
Magnetic Survey ◽  
Sources Of Information ◽  
The West ◽  
Mean Values ◽  
The City ◽  
Central Station ◽  
Previous Occasion ◽  
Made In

This survey, which occupied a considerable portion of the months of August and September 1869, is a continuation of the series of observations made in the west of France during the preceding year. The instruments used were the same on both occasions, the only changes made for the second expedition being (1°) the substitution of a theodolite by Jones in lieu of Cooke’s transit-theodolite, which was slightly too heavy for carrying in the hand, and (2°) the procuring, through the kindness of Dr. Stewart, a second tripod stand similar to our own, which rendered the series of observations with two observers much more rapid than on the previous occasion. The observations were undertaken, as before, by the Rev. W. Sidgreaves and myself, the Vibrations and Deflections falling to his share, and the Declination and Chronometer comparisons remaining in my hands, whilst the Dip was in general observed by both. The method of reduction is almost identical with that adopted for the observations taken in the west of France. The geographical positions of the different stations have been calculated, as far as possible, from the data given in the 'Connaissance des Temps,’ but where this could not be done I have had recourse to the most reliable sources of information at my command. For the accurate determination of the positions of Mont Rolland (near Dôle), of N. D. de Myans (near Chambéry), of Mongré (near Villefranche-sur-Soane), of Iseure (near Moulins), and of our station at Marseilles I am indebted to the kindness of the Rev. N. Larcher, S. J., Membre de la Société Météorologique de France. The coordinates of Vaugirard were readily obtained from a good map of Paris, and for Issenheim and Monaco I have to depend on Cassini’s ‘Carte Générale de la France’ and on Philip’s 'Imperial Atlas.’ The Imperial Observatory at Paris is chosen as the natural position for the origin of coordinates, in lieu of our central station of observation at Vaugirard, which lies on the outskirts of the city; the resulting mean values will thus require no correction, and will be immediately comparable with those of most other observers.

Glomerular permeability in the fetal rabbit

1978 ◽  
Vol 36 (2) ◽  
pp. 681A-681B ◽  
Author(s):  
M. L. Monica ◽  
M. L. Zimny ◽  
S. G. McClugage
Keyword(s):  
New Zealand ◽  
Age Differences ◽  
Accurate Determination ◽  
Ethyl Carbamate ◽  
Lower Abdomen ◽  
Glomerular Permeability ◽  
Small Incision ◽  
New Zealand White Rabbits ◽  
Made In

The purpose of this study was to determine fetal age differences in glomerular permeability using a graded series of dextrans (Pharmacia, Inc., Uppsala, Sweden). The dextran fractions were highly purified and consisted of the following sizes: T-10, T-40 and T-110 (10,000, 40,000 and 110,000 M.W. respectively). The foundation for this study was the work of Caulfield and Farquhar, who showed, using a graded series of dextrans, that the basement membrane was the definitive barrier to permeability.A total of 120 fetuses of pregnant New Zealand white rabbits at the following periods of gestation: 20, 22, 24, 28 days and one day old neonates were utilized. Accurate determination of each fetus' developmental stage was based on weight and crown-rump measurements made at the time of sacrifice. Pregnant rabbits were anesthesized with 20% urethane (ethyl carbamate) and a longitudinal incision was made in the shaved lower abdomen. A small incision was placed in the exposed uterus which penetrated the amniotic sac allowing for removal of the fetus. Viability of the fetus was essential and each fetus remained attached to the placenta throughout the course of dextran injection.

THE IEC METHOD AND CONVERSION COEFFICIENTS OF THE 605-keV TRANSITION IN 134Ba

1966 ◽  
Vol 44 (3) ◽  
pp. 549-562 ◽  
Author(s):  
E. F. Zganjar ◽  
J. H. Hamilton
Keyword(s):  
Beta Decay ◽  
Photon Energy ◽  
Conversion Coefficient ◽  
Theoretical Calculations ◽  
Accurate Determination ◽  
A Value ◽  
Conversion Coefficients ◽  
Double Focusing ◽  
Made In

Tests of the internal–external method of measuring conversion coefficients in the Vanderbilt double-focusing spectrometer have been made in search of possible errors arising from scattering of photoelectrons in the converter for a photon energy of 605 keV. This scattering may affect the factor, f, which corrects for the anisotropic distribution of the photoelectrons. The 605-keV transition in 134Ba populated by the beta decay of 134Cs was used. An accurate determination of the K, L, and M conversion coefficients of the 2+ to 0+, 605-keV, E2 transition in 134Ba was made. Three uranium converters 1.12, 2.19, and 3.71 mg/cm2 thick were used. The results are compared with the new theoretical calculations of f which depend on the converter thickness and consequently consider the effect of scattering. For photons of energy 605 keV or greater, the IEC method used in the Vanderbilt double-focusing spectrometers is insensitive (< 5%) to scattering in uranium converters < 4 mg/cm2 thick. The K, L, and M conversion coefficients were determined to be (5.03 ± 0.20) × 10−3, (7.07 ± 0.50) × 10−4, and (1.64 ± 0.18) × 10−4, respectively. The respective theoretical values of Rose are 5.08 × 10−3, 6.92 × 10−4, and 2.77 × 10−4. Sliv and Band give a value of 5.10 × 10−3 for the K conversion coefficient.

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