Polymer Morphology Revealed by Staining Techniques

1981 ◽  
Vol 39 ◽  
pp. 340-341
Author(s):  
A. C. Reimschuessel ◽  
V. Kramer
Keyword(s):  
Polymer Melt ◽  
Nylon 6 ◽  
Morphological Features ◽  
Negative Staining ◽  
Polymer Morphology ◽  
Crystallizable Polymer ◽  
Staining Techniques ◽  
Long Chain

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.

Evidence For Four Classes of Microtubules in Individual Cells

1967 ◽  
Vol 2 (2) ◽  
pp. 169-192
Author(s):  
O. BEHNKE ◽  
A. FORER
Keyword(s):  
Colchicine Treatment ◽  
Negative Staining ◽  
The Other ◽  
Pepsin Digestion ◽  
Sperm Tail ◽  
Staining Techniques ◽  
Cytoplasmic Microtubules ◽  
Experimental Treatments

Experiments were performed on crane-fly spermatids (Nephrotoma suturalis Loew), ratsperm, and rat tracheal cilia to test whether all microtubules respond in the same way to different treatments. Crane-fly spermatids contain cytoplasmic microtubules, accessory tubules, and the 9 + 2 complex of tubules; rat sperm and rat tracheal cilia contain only the 9 + 2 tubules. Crane-fly spermatid tubules responded to the experimental treatments as follows. After colchicine treatment, or storage at 0 °C, the cytoplasmic microtubules disappeared, while the 9 + 2 tubules were normal. After storage at 50 °C the cytoplasmic microtubules disappeared, and then the 9 + 2 tubules were affected: first the central tubules and B-tubules were affected, and later the A-tubules. After brief pepsin treatment, the 9 doublet tubules disappeared, while the other tubules appeared normal; after prolonged pepsin treatment the accessory, central, and cytoplasmic tubules disappeared. After negative staining at pH 7, the cytoplasmic microtubules were never seen, the central tubules were only sometimes seen, the B-tubules were sometimes fragmented, and the A-tubules were intact. On the basis of these responses, it was concluded that there are 4 classes of tubules in crane-fly spermatids, namely cytoplasmic microtubules; accessory tubules and central tubules (of the 9 + 2 complex); B-tubules (of the 9 + 2 complex); and A-tubules (of the 9 + 2 complex). At least some of the different responses appeared to be due to intrinsic physical and/or chemical differences between the tubules themselves. Pepsin digestion and negative staining of rat sperm tails gave results similar to those with crane-fly spermatids. In addition, the 9 + 2 tubules responded differently to pepsin digestion at different points along their length. This gradient of sensitivity was attributed to synthesis of new tubules occurring at one end of the sperm tail. Pepsin digestion and negative staining of rat tracheal cilia gave results similar to those with crane-fly spermatids and rat sperm tails. All the tubules had a similar substructure, as revealed by negative-staining techniques. It was concluded that microtubules are proteinaceous, at least in part, and that microtubules are different in composition from membranes. It is suggested that the walls of the B-tubules are composed of two materials--(1) the portions adjacent to the A-tubules, and (2) the remaining portion.

The diffusion of long-chain molecules through bulk polyethelene

1979 ◽  
Vol 365 (1720) ◽  
pp. 53-73 ◽  
Keyword(s):  
Polymer Melt ◽  
Appreciable Effect ◽  
Interfacial Resistance ◽  
Chain Molecules ◽  
Surface Migration ◽  
The Matrix ◽  
Activation Energy For Diffusion ◽  
Matrix Morphology ◽  
Entangled Polymer ◽  
Long Chain

This paper describes an experimental study of the centre of mass diffusion of linear hydrocarbon or deuterocarbon molecules, of the type (CH 2 ) N or (CD 2 ) N , through bulk polyethylene. N was varied between about 15 and 1500. The diffusion coefficient D was measured as a function of temperature, matrix morphology and diflfusant chain length, both in semi-crystalline and molten polyethylene. The technique used involved labelling the diflfusants so that they absorbed radiation in the infrared spectrum in a region relatively free of absorption by the matrix. Infrared microdensitometry was used to measure diffusion broadening of a known diffusant concentration distribution, and hence to evaluate D . The method avoids problems presented by interfacial resistance and surface migration effects and can also account for the effect of diffusant polydispersity. The diffusion was found to be Fickian and essentially independent of concentration, for the diflfusants used, up to 2%. The data indicate that the morphology of the disordered interlamellar region can have an appreciable effect on the mobility of long-chain diffusants. They also suggest that the activation energy for diffusion in the melt becomes independent of diflfusant length beyond a certain lower limit. The results provide support for de Gennes’s (1971) model of snake-like motion (reptation) for polymeric diflfusants in an entangled polymer melt, and suggest that such motion persists down to a diflfusant size of some 30-(CH 2 )-backbone units.

scholarly journals Chlorine-Susceptible and Chlorine-Resistant Type 021N Bacteria Occurring in Bulking Activated Sludges

2001 ◽  
Vol 67 (11) ◽  
pp. 5303-5307 ◽  
Author(s):  
M. A. Séka ◽  
Y. Kalogo ◽  
F. Hammes ◽  
J. Kielemoes ◽  
W. Verstraete
Keyword(s):  
In Situ Hybridization ◽  
Fluorescent In Situ Hybridization ◽  
Morphological Features ◽  
The Other ◽  
Filamentous Bacteria ◽  
Staining Techniques ◽  
Effect Of Chlorine

ABSTRACT Two filamentous bacteria causing bulking in two activated sludges were examined. Investigations using morphological features, staining techniques, and fluorescent in situ hybridization identified both filaments as type 021N. However, an examination of the effect of chlorine on the sludges revealed a chlorine-susceptible type 021N in one sludge and a chlorine-resistant type 021N in the other.

Crystallization kinetics and morphological features of star-branched nylon-6: effect of branch-point functionality

Polymer ◽  
1993 ◽  
Vol 34 (11) ◽  
pp. 2330-2343 ◽  
Author(s):  
Brian G. Risch ◽  
Garth L. Wilkes ◽  
John M. Warakomski
Keyword(s):  
Crystallization Kinetics ◽  
Branch Point ◽  
Nylon 6 ◽  
Morphological Features

scholarly journals A FINE STRUCTURAL ANALYSIS OF INTERCELLULAR JUNCTIONS IN THE MOUSE LIVER

1970 ◽  
Vol 45 (2) ◽  
pp. 272-290 ◽  
Author(s):  
Daniel A. Goodenough ◽  
Jean Paul Revel
Keyword(s):  
Gap Junctions ◽  
Mouse Liver ◽  
Intercellular Junctions ◽  
Uranyl Acetate ◽  
Bile Canaliculus ◽  
Negative Staining ◽  
En Bloc ◽  
Intact Mouse ◽  
Zonula Occludens ◽  
Staining Techniques

Zonulae occludentes and gap junctions were examined both in the intact mouse liver and in a junction-rich membrane fraction from homogenized mouse liver. These preparations were visualized with the techniques of uranyl acetate staining en bloc, staining with colloidal lanthanum, negative staining with phosphotungstate, and freeze-cleaving. The zonula occludens is arranged as a meshwork of branching and anastomosing threadlike contacts sealing the lumen of the bile canaliculus from the liver intercellular space. The gap junction is characterized in section by a 20 A gap between the apposed junctional membrane outer leaflets, and permeation of this space with lanthanum or phosphotungstate reveals a polygonal lattice of subunits with a center-to-center spacing of 90–100 A. Freeze-cleaved gap junctions show a similar lattice. Extraction of junction-rich fractions with 60% aqueous acetone results in a disappearance of the 20 A gap in sectioned pellets and an inability to demonstrate the polygonal lattice with either the freeze-cleave or negative staining techniques. Extraction of the membranes with 50% acetone does not produce this effect. Thin-layer chromatography of the acetone extracts reveals a group of phospholipids in the 60% extract that are not detectable in the 50% extract. Acetone does not cause any detectable change in the structure of the zonula occludens, but the occluding junction becomes leaky to lanthanum following acetone treatment. The effects of other reagents on the junctions are reported.

Observation of a Central Subunit in Annelid Extracellular Hemoglobins using the Stem Digital Image Processing Techniques

1982 ◽  
Vol 40 ◽  
pp. 704-705
Author(s):  
M. Ohtsuki ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Negative Staining ◽  
Image Processing Techniques ◽  
Staining Techniques ◽  
Processing Techniques

Extracellular hemoglobins of annelids consist of 12 subunits with appearance of superposed hexagons. So far, electron microscopy using negative staining techniques indicated that only the hemoglobins of Nephtys and Oenone contain an additional central subunit.

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