Flow behavior of dilute polyacrylamide solutions through porous media. 2. Indirect determination of extremely high molecular weights and some aspects of viscosity decrease over long time intervals

1984 ◽  
Vol 23 (3) ◽  
pp. 316-319 ◽  
Author(s):  
Raimund Haas ◽  
Werner Michael Kulicke
Keyword(s):  
Porous Media ◽  
Flow Behavior ◽  
Time Intervals ◽  
Indirect Determination ◽  
Molecular Weights ◽  
Long Time

DETERMINATION OF RADIO SOURCES LOCATION BY THE METHOD OF "IMAGINARY BASE" WHEN USING THE LINEAR MODEL

2018 ◽  
pp. 124-130
Author(s):  
Yu. V. Petrov ◽  
S. I. Bakaras ◽  
S. A. Yukhno
Keyword(s):  
Radio Source ◽  
Linear Model ◽  
Source Location ◽  
Time Interval ◽  
Radio Sources ◽  
Time Intervals ◽  
Potential Accuracy ◽  
Long Time ◽  
Geometrical Factors

This article presents the expressions which allow evaluating the potential accuracy of radio source location by the method of «imaginary base» when using the linear model of changing the bearing on it. The concept of the method of «imaginary base» is to be used in solving the triangulation problem not only of measuring bearing, but also their extrapolated values at a certain time interval. Potential characteristics is determined by accuracy, dynamic and geometrical factors, bearing measurement and extrapolation times. The article shows that when using a linear model, there are limitations both on the time of measuring bearing and on the time of extrapolation. It will be because of the increase in the variance of the error of estimating the distance. Limiting of series decomposition members number of non-linear bearing change dependence from time there are. It depends on the speed of changing bearing (depends on the range and speed) and the initial bearing (depends on the track angle). Extrapolation over long time intervals is possible only at long distances and at relatively low speeds.

Determination of the Molecular Weights and the Structures of Rubber, Gutta-Percha and Balata. Communication No. 258 on Macromolecular Compounds. Communication No. 49 on Isoprene and Rubber

1942 ◽  
Vol 15 (3) ◽  
pp. 473-522
Author(s):  
H. Staudinger ◽  
Kl Fischer
Keyword(s):  
Small Molecules ◽  
Colloidal Particles ◽  
High Viscosity ◽  
Molecular State ◽  
Colloidal Solutions ◽  
Great Tendency ◽  
Molecular Weights ◽  
Gutta Percha ◽  
Long Time

Abstract The method used to determine the constitutions of rubber, gutta-percha and balata is essentially the same as that used for organic substances of low molecular weights, i.e., the substance is dissolved in a solvent, and the size and character of the particles in solution are determined. For a long time the nature of colloidal solutions of these hydrocarbons was in dispute. Up to twenty years ago, it was commonly assumed that the molecules of these hydrocarbons are relatively small, and that their colloidal particles are formed by the assemblage of small molecules into micelles through the agency of secondary forces. It seemed to Pummerer, Nielsen and Gündel that in certain solvents, such as camphor and menthol, rubber is dissolved in a low-molecular state. Subsequently, however, this observation was proved to be incorrect. According to the opinion of Meyer and Mark, colloidal particles of rubber are composed of relatively long primary-valence chains, which contain from 75–150 isoprene residues. These chains are, in turn, assembled into micelles by “micellar forces.” The authors explain this in the following way: “The high viscosity of rubber solutions, e.g., in benzene, would lead one to conclude that very large, highly solvated micelles are present in these solvents.” At the time, this hypothesis seemed to explain quite satisfactorily the nature of rubber and its solutions, for the great tendency of these solutions to undergo certain changes on standing, which are manifest by an increase or decrease in viscosity, is readily comprehensible on this basis.

scholarly journals The scattering of light in protein solutions. I—Gelatin solutions and gels

1930 ◽  
Vol 129 (811) ◽  
pp. 490-508 ◽  
Keyword(s):  
Analytical Data ◽  
Sedimentation Velocity ◽  
Sedimentation Equilibrium ◽  
Protein Solutions ◽  
Scattering Of Light ◽  
Molecular Weights ◽  
Protein Molecules ◽  
Long Time ◽  
And Diffusion

In a previous paper, the investigation of the scattering of light in agar sols and gels was described and a view regarding the changes taking place in the system during gelation was developed. In a series of paper, of which this is the first, the author proposes to publish investigations of the scattering of light in protein solutions. The various physical properties of the different proteins have been studied for a long time past. Several workers have tried to evaluate the molecular weights of the proteins from the osmotic pressure of their solutions and also from analytical data. Recently a very precise and definite method for the determination of the molecular weights of the proteins, based upon the sedimentation of these heavy molecules in the ultra-centrifuge, has been successfully developed by Svedberg. The molecular weight can be determined in two ways:—(I) by the measurement of the sedimentation equilibrium reached in the cell as a result of the centrifugal and diffusion forces; (II) by measuring the sedimentation velocity of the protein molecules in high centrifugal fields.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Tingkat Pemahaman Kompetensi Guru Pada Mahasiswa Pendidikan Geografi Sebagai Calon Guru Geografi

2020 ◽  
Vol 21 (1) ◽  
pp. 102-117
Author(s):  
Novia Zalmita ◽  
Muhajirah Muhajirah ◽  
Abdul Wahab Abdi
Keyword(s):  
Prospective Teachers ◽  
Prospective Teacher ◽  
Quantitative Description ◽  
Population Data ◽  
Geography Education ◽  
Teacher Competence ◽  
Education Department ◽  
Long Time

One that influences human resource indicators is education. The teacher is a profession as a job of academic specialization in a relatively long time in college. Understanding related to teacher competence is very important to have by a prospective teacher because it can affect the quality of performance as a professional teacher. The teacher's competence is known as pedagogic, professional, social and personality competencies. The issue in this study is how the competency of the teacher of the Department of Geography Education FKIP Unsyiah as a prospective teacher of geography? The purpose of this study was to determine the competence of teachers in the Department of Geography Education FKIP Unsyiah as prospective geography teachers. Quantitative description approach is used in this study to find answers to the issue. The population in this study were students of the Department of Geography Education FKIP Unsyiah class of 2015 and 2016 who had been declared to have passed the Micro Teaching and Magang Kependidikan 3 course totaling 50 people. Because the population is small and can be reached, the determination of the sample using total sampling techniques so that the sample in this study is the whole population. Data collection is done by distributing test questions to respondents. The data was analyzed using the descriptive statistics percentage formula. The results of the study indicate that the level of teacher competence of Geography Education Department students as prospective teachers is in the moderate category, namely as many as 22 respondents (44%). A total of 12 respondents (24%) were in the high category, 15 respondents (30%) were in the low category and 1 respondent (2%) were in the very low category.

MODELING THE NONLINEAR FLOW BEHAVIOR FOR HORIZONTAL WELL PRODUCTION IN AN UNDERGROUND POROUS-MEDIA FORMATION

2015 ◽  
Vol 18 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Cong Lu ◽  
Ren-Shi Nie ◽  
Jian-Chun Guo ◽  
Dan-Ling Wang
Keyword(s):  
Porous Media ◽  
Horizontal Well ◽  
Flow Behavior ◽  
Nonlinear Flow ◽  
Well Production ◽  
Nonlinear Flow Behavior

Influence of Geometry on Self-Diffusion of Liquid Molecules in Porous Media in Long Time Regime

2009 ◽  
Vol 12 (1) ◽  
pp. 29-41 ◽  
Author(s):  
V. A. Sevriugin ◽  
V. V. Loskutov
Keyword(s):  
Porous Media ◽  
Self Diffusion ◽  
Time Regime ◽  
Long Time
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