The Viscosity and Structure Viscosity of Rubber Solutions and Emulsions

1956 ◽  
Vol 29 (3) ◽  
pp. 880-887 ◽  
Author(s):  
J. Schurz
Keyword(s):  
Colloidal Solution ◽  
Mutual Effect ◽  
Extreme Case ◽  
Frictional Resistance ◽  
The Other ◽  
Structural Viscosity ◽  
Uniform Size ◽  
Dispersed Particles ◽  
Other Hand ◽  
Particle Form

Abstract It is well known that the increase of viscosity of a colloidal solution over that of the pure solvent is produced by the frictional resistance to flow of the dispersed particles. The amount of this viscosity increase depends to a great extent on the shape of the particles. If these are spheres, only the ratio of the volume of the solute to the solvent is involved (Einstein's law), while in the other extreme case, namely with fiber molecules, the particle size plays such an important role, as is known, that one can calculate the particle weight of the dispersed phase from the viscosity (Staudinger's law, Mark-Houwink equation). But not only is the viscosity of a colloidal solution influenced by the particle form, but also its structural viscosity depends on it to a great degree. It is easy to understand this. For if the structure viscosity and, consequently, the decrease of viscosity with increasing velocity gradient, result from the fact that the hydrodynamic forces in the flowing solution, on the one hand, orient and distort the dispersed particles in the moving stream, and, on the other hand, oppose an eventual intermolecular mutual effect or aggregate formation of the particles, it is easily seen that the flow forces will be able to manifest these effects all the more readily and markedly the more extended and the stiffer the dispersed particles are. Thus it can be expected that, in general, in spherical particle suspensions no structural viscosity will appear, but that this will manifest itself the more strongly the more asymmetric the particles. With rubber it is easily possible to realize two extremely different dispersion forms. Rubber emulsions, as they exist in the various latexes, are typical definite spherical suspensions, with rather large particles of very uniform size. In rubber solutions, on the other hand, say in toluene or benzene, there is a macromolecular distribution. The dispersed particles are the individual kinky fiber molecules of the rubber, which are known to have a more or less elongated form. In fact these two types of rubber dispersions behave so differently that each of them can be called a typical representative of its class.

scholarly journals Struktura znaczeniowa słownictwa anatomicznego w Nowym dykcjonarzu M.A. Troca

2020 ◽  
pp. 119-133
Author(s):  
Beata Kuryłowicz ◽  
Keyword(s):  
Semantic Analysis ◽  
18Th Century ◽  
The Other ◽  
Medical Terminology ◽  
Uniform Size ◽  
Semantic Relationships ◽  
Anatomical Terminology ◽  
Other Hand ◽  
Lexical Field

This article is an attempt to perform a semantic analysis of anatomical vocabulary collected by Michał Abraham Troc in Nowy dykcjonarz, published in Lipsk in 1764. The aim of individual analyses based on the lexical field theory is to demonstrate the meaning of lexemes, to determine their place within a field, as well as to disclose semantic relationships: synonymy, polysemy and hyponymy. The semantic analysis presented in this article clearly demonstrates abundance and differentiation of 18th century anatomical vocabulary, as well as prevalence of native over borrowed words. Among 250 names, only eleven units are borrowings from foreign languages: seven Latin and four German ones. This provides evidence there is a fundamental role of native lexis, especially colloquial vocabulary, in the formation of Polish anatomical terminology, and, more extensively, also medical terminology, in the first phase of its development which continued until the end of the 18th century. Of note is also the non-uniform arrangement of lexemes in individual fields and asymmetry in their number. Selected lexical fields are characterised by non-uniform size, different level of semantic stratification and differentiated degree of generality of words they contain. On the other hand, semantic relations observed in the analysed anatomical vocabulary, especially synonymy and polysemy, confirm there is a differentiation of anatomical lexis, on the other hand, they indicate lack of precision in expressing content by the discussed lexical units.

Isoprene and Rubber. XVIII. Viscosity Studies on Balata

1930 ◽  
Vol 3 (3) ◽  
pp. 516-518 ◽  
Author(s):  
H. Staudinger ◽  
E. O. Leupold
Keyword(s):  
Colloidal Particles ◽  
Colloidal Particle ◽  
Colloidal Solution ◽  
Elementary Particles ◽  
The Other ◽  
Colloidal Solutions ◽  
Specific Viscosity ◽  
Micellar Structure ◽  
Other Hand ◽  
The Stability

Abstract Varied views prevail as to the structure of the colloidal particles present in a rubber solution. According to Harries, Pummerer, and many others, these colloidal particles are formed through the association or aggregation of smaller molecules. According to Meyer and Mark they have a micellar structure, the micelles forming through the apposition of main valence chains. On the other hand, it was assumed by one of the present authors that the elementary particles in a colloidal solution of rubber are identical with the rubber molecules, these large, especially labile molecules being called macromolecules. Thus the existence of much larger molecules than any hitherto known was postulated. This view was confirmed by the conversion of rubber to hydro-rubber capable of forming colloidal solutions, and also by the pyrogenic decomposition of rubber. In order to decide definitely between the two conceptions, the stability of the colloidal particle in a rubber solution was studied by means of viscosity measurements at various temperatures as was done in the case of the polystyrols. If these colloidal particles form aggregates or if they have a micellar structure, they should decrease in size with increase in temperature, and this change should be evidenced by a diminution of the specific viscosity of the colloidal solution. On the other hand, if such a solution is composed of molecules, the specific viscosity at various temperatures is the same, provided that the molecules are not decomposed at higher temperatures. This line of research led to an explanation of the constitution of the colloidal particles in a polystyrol solution and was now applied to balata, since the latter is especially easily purified.

Identification  of the Antioxidant Capacity of Scropholaria Striata Boiss for the First Time and the Effect of Some Ecological Features on It

2018 ◽  
Author(s):  
mansureh ghavam ◽  
zahra zargoosh ◽  
ali tavili
Keyword(s):  
Antioxidant Activity ◽  
Error Probability ◽  
Mutual Effect ◽  
Ecological Factors ◽  
Total Phenol ◽  
The Other ◽  
Antioxidant Potential ◽  
Minimum Amount ◽  
Ecological Features ◽  
Other Hand

Scropholaria Striata Boiss is one of the most important medicinal plants which mostly grows in cold regions and Zagros Mountains in Iran. Although the chemical composition of this plant is not explored yet, people living in Ilam have been using it for many years in order to treat different illnesses. The present study aims to analyze the effect of some ecological factors on antioxidant potential and the amount of Phenol in this plant, and it has a random factorial design with 2 factors (height and region) and is repeated three times. The fruiting twigs of the plant were gathered in 3 height levels and in the same direction (north-east) with 100 meters distances. They were gathered from three districts of Badreh, Dareshahr, and Dehloran in Ilam province in June, 2016, when the fruits appear. Moreover, to analyze different soil chemical and physical features, soil samples were gathered from half-meter depth under the shrubs. The antioxidant action of Methanol extract from plant samples and the total amount of Phenol compounds were measured through DPPH and Folin-Ciocalteu method, respectively. Analysis of variance of data (soil and plant quantities) and comparison of means were done through F-test and Duncan-test, respectively, with error probability of 5%. After statistic data analysis, the results showed that the effects of region and height and also the mutual effect these two on antioxidant potential and total Phenol amount were significant with error probability of 1 %. The maximum extract efficiency (19.37 ± 3.07 %), antioxidant potential (126.5656 ± 0.96 µg/ mL) and the total Phenol amount (55.7689 ± 3.17 µg/ mL) were obtained from Dareshahr district in height level of 600 meters above mean sea level. Also, the minimum amount of total Phenol (24.6544 ± 3.21 µg/ mL) was recorded in the lowest height level of Badreh district in which Phosphorus, Potassium, organic carbon, organic material, Nitrogen, acidity, lime and silt had the minimum amount. On the other hand, antioxidant activity and total Phenol amount had a strong direct correlation in two districts of Dareshahr and Badreh, but were correlated reversely and strongly in Dehloran district. Therefore, it can be stated that the plant has the potential for antioxidant activity; but the complexity of ecological factors effects, on one hand, and the emerge of different chemical processes in the plant under such effects, on the other hand, has led to synthesis of different compounds which are effective on antioxidant potential of the plant in different regions.

Research on Stability of Crawler System for Deep Sea ROV

2009 ◽  
Author(s):  
Tomoya Inoue ◽  
Tokihiro Katsui ◽  
Hisataka Murakami ◽  
Junichiro Tahara
Keyword(s):  
Deep Sea ◽  
Extreme Case ◽  
Center Of Gravity ◽  
The Other ◽  
Water Tank ◽  
Fundamental Theory ◽  
Initial Investigation ◽  
Other Hand ◽  
Advantageous Effect ◽  
Stable Area

A deep sea ROV is desired to be light from the viewpoints of reducing a tension on an underwater cable and possessing the adequate movability by thrusters in water. On the other hand, when moving by a crawler system on the seabed, such a lightweight will influence on its movability characteristics. As an initial investigation experiments using an actual ROV were conducted in a water tank. And it was observed that the ROV ran in wheelie in some cases and almost fell down in extreme case in spite of the fact that it could run stably on land. In order to clarify the results fundamental theory of stability of the ROV in steady running is presented. The theory gives the discriminant chart of stable running for the combination of the center of gravity and the center of buoyancy. Experiments using a model were conducted to verify the theory. In order to increase the stable area and also to change meaningly the center of gravity, this paper proposes a method to virtually increase the weight and to change the center of gravity by using thrusters. And preliminary experiments were conducted to confirm its advantageous effect.

The Axial Frictional Resistance of Long Cylinders in Turbulent Flow

1959 ◽  
Vol 3 (03) ◽  
pp. 24-28
Author(s):  
K. Karhan
Keyword(s):  
Turbulent Flow ◽  
Flat Plate ◽  
Frictional Resistance ◽  
The Other ◽  
Ship Model ◽  
Transverse Curvature ◽  
Other Hand ◽  
Length And Area ◽  
Mathematical Relations

In ship-model extrapolation the frictional resistance of the ship surface is generally taken to be equal to that of the flat plate having the same length and area. Experiments carried out at several laboratories with models of different size show dearly that each model should have its own extrapolation curve. In spite of general agreement that this is so, the flat-plate extrapolation curve is still generally used. On the other hand it is not easy to derive mathematical relations for ship-form frictional resistance or to make extensive experiments for this purpose. It is obvious that a first step towards departing from the flat-plate resistance basis should be to study the effect of transverse curvature on frictional resistance.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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