THE EVALUATION OF THE INTRINSIC VISCOSITY (AS INTRINSIC FLOW TIME) OF GR-S IN BENZENE

1947 ◽  
Vol 25b (4) ◽  
pp. 333-350
Author(s):  
L. H. Cragg ◽  
T. M. Rogers ◽  
D. A. Henderson
Keyword(s):  
Intrinsic Viscosity ◽  
Relative Viscosity ◽  
Flow Time ◽  
Routine Work ◽  
Relative Flow

From careful measurements of the relative flow times of solutions of GR-S in benzene, it has been established that the intrinsic flow time (and hence the intrinsic viscosity) of GR-S in benzene may be most precisely determined by the use of a function [Formula: see text], based on the Baker equation relating ηr, the relative viscosity, and c, the concentration; for the GR-S–benzene system the value of n may be taken as 8. For the greatest precision [t] is determined by linear (horizontal) extrapolation, to zero concentration, of the [Formula: see text] vs. c plot; in rapid routine work [t] may be evaluated as [Formula: see text] by measurements on only one solution of a concentration such that tr = 1.8 ± 0.4.

The Terminology of Intrinsic Viscosity and Related Functions

1946 ◽  
Vol 19 (4) ◽  
pp. 1092-1098
Author(s):  
L. H. Cragg
Keyword(s):  
Intrinsic Viscosity ◽  
Kinematic Viscosity ◽  
Relative Viscosity ◽  
Flow Time ◽  
Inherent Viscosity ◽  
Routine Practice ◽  
Concentration Coefficient ◽  
Specific Viscosity ◽  
Reduced Viscosity ◽  
Relative Flow

Abstract The confusion existing in the use of symbols and names for Kraemer's “intrinsic viscosity” and other functions related to it is illustrated and deplored. The reasonable plea is made that one name be adopted for each function and that it be used with no other meaning. To stimulate discussion and ultimate action, the following names are proposed: “specific viscosity” for ηsp; “reduced viscosity” for ηsp/c, “inherent viscosity” for (ln ηr)/c; and “intrinsic viscosity” for [η], whether determined as “limiting reduced viscosity” limc→0 (ηsp/c), or as “limiting inherent viscosity” limc→0 (ηr/c), or as “limiting viscosity concentration coefficient” limc→0 (dηr/dc). Often, especially in routine practice, it is the relative kinematic viscosity νr, that is determined ; unless this is shown to be numerically equal to the relative viscosity ηr, the symbols and names of the derived functions should be modified accordingly: thus, (ln νr)/c inherent kinematic viscosity, [ν] intrinsic kinematic viscosity. Frequently, also, kinetic energy corrections are neglected; under these circumstances the suggested usage is tr, relative flow time, tsp/c reduced flow time, [t] intrinsic flow time, etc.

scholarly journals Haemorheology in dilute, semi-dilute and dense suspensions of red blood cells

2019 ◽  
Vol 872 ◽  
pp. 818-848 ◽  
Author(s):  
Naoki Takeishi ◽  
Marco E. Rosti ◽  
Yohsuke Imai ◽  
Shigeo Wada ◽  
Luca Brandt
Keyword(s):  
Red Blood Cells ◽  
Intrinsic Viscosity ◽  
Blood Cells ◽  
Volume Fraction ◽  
Relative Viscosity ◽  
Shear Plane ◽  
Constitutive Law ◽  
Stable Mode ◽  
Volume Fractions ◽  
Wide Range

We present a numerical analysis of the rheology of a suspension of red blood cells (RBCs) in a wall-bounded shear flow. The flow is assumed as almost inertialess. The suspension of RBCs, modelled as biconcave capsules whose membrane follows the Skalak constitutive law, is simulated for a wide range of viscosity ratios between the cytoplasm and plasma,$\unicode[STIX]{x1D706}=0.1$–10, for volume fractions up to$\unicode[STIX]{x1D719}=0.41$and for different capillary numbers ($Ca$). Our numerical results show that an RBC at low$Ca$tends to orient to the shear plane and exhibits so-called rolling motion, a stable mode with higher intrinsic viscosity than the so-called tumbling motion. As$Ca$increases, the mode shifts from the rolling to the swinging motion. Hydrodynamic interactions (higher volume fraction) also allow RBCs to exhibit tumbling or swinging motions resulting in a drop of the intrinsic viscosity for dilute and semi-dilute suspensions. Because of this mode change, conventional ways of modelling the relative viscosity as a polynomial function of$\unicode[STIX]{x1D719}$cannot be simply applied in suspensions of RBCs at low volume fractions. The relative viscosity for high volume fractions, however, can be well described as a function of an effective volume fraction, defined by the volume of spheres of radius equal to the semi-middle axis of a deformed RBC. We find that the relative viscosity successfully collapses on a single nonlinear curve independently of$\unicode[STIX]{x1D706}$except for the case with$Ca\geqslant 0.4$, where the fit works only in the case of low/moderate volume fraction, and fails in the case of a fully dense suspension.

Soluble wool Proteins. I. Light scattering and viscosity in Aqueous solution

1958 ◽  
Vol 11 (4) ◽  
pp. 581 ◽  
Author(s):  
BS Harrap ◽  
EF Woods
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Intrinsic Viscosity ◽  
High Speed ◽  
Guanidine Hydrochloride ◽  
Sodium Dodecyl ◽  
Relative Viscosity ◽  
Molecular Weights ◽  
Solvent Component ◽  
Wool Proteins

S-Carboxymethylkerateine 2 (SCMK2) and cc-keratose, two proteins derived from wool, have been characterized by nitrogen content, ultraviolet absorption, refractive index increment, light scattering, and intrinsic viscosity. Variations in the physical properties of different batches are attributed to different degrees of aggregation during the preparation. The relative viscosity decreased with time and was generally accompanied by an increase in turbidity, indicating aggregation. The effect of heating was to accelerate the fall in viscosity and increase in turbidity. Light scattering investigations showed that dissociation occurred on dilution and in some cases this could be detected by viscosity measurements. The molecular weight of several millions for SCMK2 at pH 6.7 was reduced to less than 1 million by removal of large aggregates by high-speed centrifuging, with an increase in both dissymmetry and intrinsic viscosity. In alkaline buffers at pH 10.5 the proteins were further dissociated and gave molecular weights of the order of 450,000. The behaviour of α-keratose was similar to that of SCMK2. Measurements on SCNK2 carried out in the presence of sodium dodecyl sulphate gave a molecular weight of 142,000 for the detergent-protein complex, corresponding to 95,000 for the protein, the dissymmetry was near unity and the intrinsic viscosity 0.115 dl/g. In 10M acetic acid, 8M urea, and 641 guanidine hydrochloride the apparent molecular weights were 95,000, 140,000, and 210,000 respectively, but these values are only upper limits because of possible selective solvation of the solvent component in such three-component systems.

A NOTE ON THE VARIATION WITH TEMPERATURE OF THE INTRINSIC VISCOSITY OF GR-S IN BENZENE

1947 ◽  
Vol 25b (4) ◽  
pp. 351-356
Author(s):  
T. M. Rogers ◽  
D. A. Henderson ◽  
L. H. Cragg
Keyword(s):  
Intrinsic Viscosity ◽  
Kinematic Viscosity ◽  
Flow Time ◽  
Point Determination ◽  
The One

The intrinsic viscosity, [η], (as well as the intrinsic flow time, [t], and the intrinsic kinematic viscosity, [ν]) of normal GR-S in benzene has been shown to be independent of temperature, over the range 10° to 55 °C, within the experimental precision [Formula: see text]. In this range of temperatures, also, the functions [Formula: see text] and [Formula: see text] are independent of concentration (up to at least 0.3%), and may therefore be used in the one-point determination of [t] and [ν].

THE DEGRADATION OF POLYSTYRENE: III. THE SCISSION OF POLYSTYLENE BY A VARIETY OF AGENTS AND THE ROLE PLAYED BY THE SOLVENT IN THIS PROCESS

1950 ◽  
Vol 28b (7) ◽  
pp. 429-440 ◽  
Author(s):  
D. S. Montgomery ◽  
C. A. Winkler
Keyword(s):  
Thermal Degradation ◽  
Linear Function ◽  
Benzoyl Peroxide ◽  
Chain Length ◽  
Intrinsic Viscosity ◽  
Structural Unit ◽  
Length Distribution ◽  
Relative Viscosity ◽  
Chain Length Distribution

For a number of polystyrenes possessing the Kuhn–Schulz chain length distribution but of different mean chain length, the relation was established between the intrinsic viscosity and the corresponding relative viscosity of a 16% solution in toluene, to facilitate the study of the scission process under conditions similar to those employed by Mesrobian and Tobolsky. It was found that this relation failed to distinguish between those scission points introduced during polymerization and those due to the subsequent degrading action of benzoyl peroxide and air. Assuming polystyrene prepared in a similar manner to that described by Mesrobian and Tobolsky possessed the Kuhn–Schulz chain length distribution it was possible to show that the average number of scission points per structural unit was a linear function of the mass of benzoyl peroxide added to the system and the number of hours exposure to light. The thermal degradation of polystyrene was studied both in the presence and the absence of toluene, and the role of the solvent in the scission of polystyrene by benzoyl peroxide and air was investigated.

A Simple Dichromatic Stain for Plastic Embedded Tissues

1970 ◽  
Vol 28 ◽  
pp. 296-297 ◽  
Author(s):  
G. R. Mackay ◽  
M. L. Mead
Keyword(s):  
Electron Microscopy ◽  
Toluidine Blue ◽  
Biological Material ◽  
Good Reproducibility ◽  
Routine Work ◽  
Staining Techniques

Color contrasting of 1 to 2 micron sections of plastic embedded biological material is an important adjunct to electron microscopy. The procedures in general use today are simple and rapid giving monochromatic results, e.g., toluidine blue. Although many di- and polychromatic histologic staining techniques have been modified to obtain a counterstaining effect with plasticembedded tissue, the methods are usually undesirable for routine work because they are time consuming, complicated and often defy good reproducibility.

Etching of Polymers by Oxygen Plasma

1968 ◽  
Vol 26 ◽  
pp. 408-409
Author(s):  
Virgil Peck ◽  
W. L. Carter
Keyword(s):  
Molecular Weight ◽  
Oxygen Plasma ◽  
Flow Time ◽  
Microscopical Study ◽  
Surface Layers ◽  
Organic Vapors ◽  
Sample Position ◽  
Accuracy Of Measurement ◽  
Bulk Polymers ◽  
Electron Microscopical

Any electron microscopical study of the morphology of bulk polymers has throughout the years been hampered by the lack of any real ability to produce meaningful surface variations for replication. True etching of polymers should show crystalline and amorphous regions in some form of relief. The use of solvents, acids, organic vapors, and inert ion bombardment to etch samples has proved to be useful only in limited applications. Certainly many interpretations of these results are subject to question.The recent use of a radiofrequency (R. F.) plasma of oxygen to degrade and remove organic material with only minor heating has opened a new possibility for etching polymers. However, rigid control of oxygen flow, time, current, and sample position are necessary in order to obtain reproducible results. The action is confined to surface layers; the molecular weight of the polymer residue after heavy etching is the same as the molecular weight of the polymer before attack, within the accuracy of measurement.

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