Revision of the atomic weight of arsenic. Part II. (Synthesis and analysis of arsenic tribromide)

1936 ◽  
Vol 8 ◽  
pp. 485-495
Author(s):  
J. H. Křepelka ◽  
M. Kočnar
Keyword(s):  
Atomic Weight

Elemental Analysis of Phloem Tissue in Lemna Minor Root Tips

1980 ◽  
Vol 38 ◽  
pp. 798-799
Author(s):  
Patrick Echlin ◽  
Thomas Hayes ◽  
Clifford Lai ◽  
Greg Hook
Keyword(s):  
Vascular Tissue ◽  
Lemna Minor ◽  
Atomic Weight ◽  
Companion Cell ◽  
Root Tips ◽  
Phloem Tissue ◽  
Cell Stage ◽  
Phloem Parenchyma ◽  
Parenchyma Cells ◽  
Xylem Element

Studies (1—4) have shown that it is possible to distinguish different stages of phloem tissue differentiation in the developing roots of Lemna minor by examination in the transmission, scanning, and optical microscopes. A disorganized meristem, immediately behind the root-cap, gives rise to the vascular tissue, which consists of single central xylem element surrounded by a ring of phloem parenchyma cells. This ring of cells is first seen at the 4-5 cell stage, but increases to as many as 11 cells by repeated radial anticlinal divisions. At some point, usually at or shortly after the 8 cell stage, two phloem parenchyma cells located opposite each other on the ring of cells, undergo an unsynchronized, periclinal division to give rise to the sieve element and companion cell. Because of the limited number of cells involved, this developmental sequence offers a relatively simple system in which some of the factors underlying cell division and differentiation may be investigated, including the distribution of diffusible low atomic weight elements within individual cells of the phloem tissue.

Interpretation and use of standard atomic weights (IUPAC Technical Report)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Adriaan M. H. van der Veen ◽  
Juris Meija ◽  
Antonio Possolo ◽  
David Brynn Hibbert
Keyword(s):  
Monte Carlo ◽  
Atomic Weight ◽  
Standard Uncertainty ◽  
Uncertainty In Measurement ◽  
Propagation Of Uncertainty ◽  
A Value ◽  
The Monte Carlo Method ◽  
Technical Report ◽  
Molecular Masses ◽  
Expression Of Uncertainty

Abstract Many calculations for science or trade require the evaluation and propagation of measurement uncertainty. Although relative atomic masses (standard atomic weights) of elements in normal terrestrial materials and chemicals are widely used in science, the uncertainties associated with these values are not well understood. In this technical report, guidelines for the use of standard atomic weights are given. This use involves the derivation of a value and a standard uncertainty from a standard atomic weight, which is explained in accordance with the requirements of the Guide to the Expression of Uncertainty in Measurement. Both the use of standard atomic weights with the law of propagation of uncertainty and the Monte Carlo method are described. Furthermore, methods are provided for calculating uncertainties of relative molecular masses of substances and their mixtures. Methods are also outlined to compute material-specific atomic weights whose associated uncertainty may be smaller than the uncertainty associated with the standard atomic weights.

scholarly journals Polyelectrolyte Gels Formed by Filamentous Biopolymers: Dependence of Crosslinking Efficiency on the Chemical Softness of Divalent Cations

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 41
Author(s):  
Katrina Cruz ◽  
Yu-Hsiu Wang ◽  
Shaina A. Oake ◽  
Paul A. Janmey
Keyword(s):  
Alkaline Earth ◽  
Divalent Cations ◽  
Transition Metal Ions ◽  
Atomic Weight ◽  
Mechanical Resistance ◽  
Flexible Polymers ◽  
Interpenetrating Networks ◽  
Charge Densities ◽  
Polyelectrolyte Gels ◽  
Different Types

Filamentous anionic polyelectrolytes are common in biological materials. Some examples are the cytoskeletal filaments that assemble into networks and bundled structures to give the cell mechanical resistance and that act as surfaces on which enzymes and other molecules can dock. Some viruses, especially bacteriophages are also long thin polyelectrolytes, and their bending stiffness is similar to those of the intermediate filament class of cytoskeletal polymers. These relatively stiff, thin, and long polyelectrolytes have charge densities similar to those of more flexible polyelectrolytes such as DNA, hyaluronic acid, and polyacrylates, and they can form interpenetrating networks and viscoelastic gels at volume fractions far below those at which more flexible polymers form hydrogels. In this report, we examine how different types of divalent and multivalent counterions interact with two biochemically different but physically similar filamentous polyelectrolytes: Pf1 virus and vimentin intermediate filaments (VIF). Different divalent cations aggregate both polyelectrolytes similarly, but transition metal ions are more efficient than alkaline earth ions and their efficiency increases with increasing atomic weight. Comparison of these two different types of polyelectrolyte filaments enables identification of general effects of counterions with polyelectrolytes and can identify cases where the interaction of the counterions and the filaments exhibits stronger and more specific interactions than those of counterion condensation.

scholarly journals III. A critical study of spectral series.— Part I. The alkalies H and He

1911 ◽  
Vol 210 (459-470) ◽  
pp. 57-111 ◽  
Keyword(s):  
Principal Series ◽  
Atomic Weight ◽  
Spectral Lines ◽  
Critical Study ◽  
Spectral Series ◽  
Observational Error ◽  
Present Communication ◽  
Present Purpose

The following investigation was commenced some years ago, at a time when the discussion as to the atomic weight of Radium raised the question as to the dependence on their atomic weights of the wave-lengths of corresponding spectral lines of different elements of the same group. The arguments were necessarily vague and unconvincing in the absence of any exact knowledge as to the connection of wave­-length with atomic weight, even supposing such connection existed. Our knowledge of series spectra is chiefly—one might say almost wholly—due to the sets of very exact measurements of Kayser and Runge, and of Runge and Paschen, supplemented by extensions to longer and shorter wave-lengths by Bergmann, Konen and Hagenbach, Lehmann, Ram age, and Saunders. These have been only quite recently added to by Paschen and by the remarkable extension of the Sodium Principal series up to 48 terms by Wood. A most valuable feature of Kayser’s work was the publication of possible errors of observation. This has rendered it possible to test with certainty whether any relation suggesting itself is true within limits of observational error or not. In fact, without this, the investigation, of which the present communication forms a first part, could not have been carried out. So far as the author knows, Saunders is the only other observer who has accompanied his observations with estimates of this kind. Others have given probable errors—practically estimates of the exactness with which they can repeat readings of that feature of a line which they take to be the centre—an estimate of little value for the present purpose. In deducing data from a set of lines it is thus possible to express their errors in terms of the original errors in the observations, and limits to the latter give limiting variations to the former. We therefore know with certainty what latitude in inferences is permissible, and are often enabled to say that such inference is not justifiable.

Deformed space–time transformations in Mercury

2017 ◽  
Vol 31 (23) ◽  
pp. 1750168 ◽  
Author(s):  
F. Cardone ◽  
G. Albertini ◽  
D. Bassani ◽  
G. Cherubini ◽  
E. Guerriero ◽  
...  
Keyword(s):  
Neutron Emission ◽  
Lorentz Invariance ◽  
Analytical Techniques ◽  
Solid Material ◽  
Transformation Product ◽  
Atomic Weight ◽  
Space Time ◽  
Invariance Violation ◽  
Icp Ms ◽  
Aisi 304 Steel

A mole of Mercury was suitably treated by ultrasound in order to generate in it the same conditions of local Lorentz invariance violation that were generated in a sonicated cylindrical bar of AISI 304 steel and that are the cause of neutron emission during the sonication. After 3 min, part of the mercury turned into a solid material which turned out to contain isotopes having a different mass (higher and lower) with respect to the isotopes already present in the initial material (mercury). These transformations in the atomic weight without gamma production above the background are brought about during Deformed Space–Time reactions. We present the results of the analyses performed on samples taken from the transformation product. The analyses have been done in two groups, the first one using five different analytical techniques: ICP-OES, XRF, ESEM-EDS, ICP-MS, INAA. In the second group of analyses, we used only two techniques: INAA and ICP-MS. The second group of analyses confirmed the occurring of the transformations in mercury.

Ellen Gleditsch: Duty and responsibility in a research and teaching career, 1916-1946

2005 ◽  
Vol 36 (1) ◽  
pp. 131-188 ◽  
Author(s):  
ANNETTE LYKKNES ◽  
LISE KVITTINGEN ◽  
ANNE KRISTINE BØØRRESEN
Keyword(s):  
Scientific Work ◽  
Atomic Weight ◽  
Associate Professor ◽  
Full Professor ◽  
Research And Teaching ◽  
Grant Applications ◽  
Network Building ◽  
Ellen Gleditsch ◽  
University Of Oslo ◽  
The University

ABSTRACT Ellen Gleditsch (1879-1968) became Norway's first authority of radioactivity and the country's second female professor. After several years in international centers of radiochemistry, Gleditsch returned to Norway, becoming associate professor and later full professor of chemistry. Between 1916 and 1946 Gleditsch tried to establish a laboratory of radiochemistry at the University of Oslo, a career which included network building, grant applications, travels abroad, committee work, research, teaching, supervision, popularization, and war resistance work. Establishing a new field was demanding; only under her student, Alexis Pappas, was her field institutionalized at Oslo. This paper presents Gleditsch's everyday life at the Chemistry Department, with emphasis on her formation of a research and teaching laboratory of radiochemistry. Her main scientific work during this period is presented and discussed, including atomic weight determination of chlorine, age calculations in minerals, the hunt for actinium's ancestor and investigations on 40K.

I. NOTES ON SODIUM COLUMBATES. II. THE ATOMIC WEIGHT OF COLUMBIUM.

1915 ◽  
Vol 37 (8) ◽  
pp. 1783-1797 ◽  
Author(s):  
Edgar F. Smith ◽  
Walter K. Van Haagen
Keyword(s):  
Atomic Weight
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