Stereoscopic analyses of surfaces on polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 706-707
Author(s):  
E.F. Lindsey ◽  
C. W. Price ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Cell Size ◽  
Cell Walls ◽  
Low Density ◽  
Polystyrene Foam ◽  
Unique Challenge ◽  
Surface Finishes ◽  
Cell Layers ◽  
A Cell ◽  
Geometric Surface

Analysis of surface finishes on machined polystyrene foam presents a unique challenge when the cell size of the foam is of the order of or larger than desired surface finishes. Ideally, the surface could be defined as the geometric surface formed by the locus of the severed edges of the cell walls. However, both machining and grinding tend to rip and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Machined geometric surfaces can be defined as the locus of the tips of the asperities, but the surface in between asperities can extend several cell layers below the asperities. The severe nature of this problem is emphasized by stereoscopic examinations of fractured, machined and ground, and cryo-vibratomed polystyrene surfaces in the SEM.Since coating does not seriously distort low-density polystyrene foam, the specimens were gold-palladium coated for examination in a Hitachi S-800 FESEM at 5 kV. Stereo pairs were obtained using tilts of + and − 3 1/2 degrees. The polystyrene foam had a cell size that varied between 2 to 11 μm.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

In vivo and in sacco digestibility and rumen microbial degradation of cell walls of soyabean and rape integuments and of dehydrated beet pulp in sheep, observed by scanning electron microscopy

1990 ◽  
Vol 115 (3) ◽  
pp. 429-435 ◽  
Author(s):  
E. Grenet ◽  
P. Barry
Keyword(s):  
Microbial Degradation ◽  
Cell Walls ◽  
Cell Layer ◽  
Aleurone Layer ◽  
Palisade Layer ◽  
Cell Layers ◽  
Beet Pulp ◽  
A Cell ◽  
In Sacco

SUMMARYThe in vivo digestibility of soyabean integuments, rape integuments and dehydrated beet pulp was determined in sheep in the Centre de Recherches de Clermont-Ferrand-Theix, in 1985. Organic matter digestibility was 83·5, 59·6 and 85·0%, respectively, for the three feeds. The nylon bag method was used to determine the disappearance of dry matter (DM) in the rumen. After 72 h, 89 and 96% DM had disappeared for soyabean integuments and beet pulp, respectively, but only 61% for rape integuments. The DM disappearance rate was slowest (P < 0·05) for soyabean integuments. Microscopic examination showed that the different layers of the soyabean integument could be ranked in increasing order of resistance to microbial degradation as follows: parenchyma, aleurone layer, column cell layer, palisade layer and epidermis. The hilum area was the most resistant and the only one lignified. The cell layers of the rape integument could be ranked in increasing order of resistance as follows: epidermis, aleurone layer and palisade layer. The last was highly lignified and not degradable. Degradation of beet pulp was fast, occurring first in the parenchyma. The vessels resisted degradation but were only a small part of the feed. This study shows why beet pulp has a low fill value and allows high intake. The soyabean integument is very digestible and is degraded slowly, whereas almost half of the rape integument is made up of a cell layer that is not degradable.

Spindle scaling mechanisms

2020 ◽  
Vol 64 (2) ◽  
pp. 383-396
Author(s):  
Lara K. Krüger ◽  
Phong T. Tran
Keyword(s):  
Cell Size ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Post Translational Modification ◽  
Size Dependent ◽  
A Cell ◽  
Chromosome Separation ◽  
Spindle Elongation ◽  
Protein Gradients ◽  
Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

Emulsion flow which preparation excludes a presence of mechanical impurities

2012 ◽  
Vol 9 (2) ◽  
pp. 118-122
Author(s):  
A.A. Rakhimov
Keyword(s):  
Cell Size ◽  
First Case ◽  
A Cell ◽  
Emulsion Flow ◽  
Blocking Mechanism

Experiments were carried out with waterhydrocarbon emulsions with various emulsifiers in capillaries with a length of 2 cm, diameters of 40 and 100 µm. To eliminate the influence of mechanical impurities comparable in size with the diameter of the capillary in first case emulsion components were filtered through fine-meshed filters. In second case obtained that way emulsion was additionally filtered through a system consisting of 3 filters with a cell size of 30-40 microns. In a capillary of 100 µm such emulsion came in a blocked state. Additional filtration of the emulsion through the mesh filters have led to an increase in viscosity but in 100 µm capillaries the time until the blocking 2-3 times more than the original. Rheology of used emulsions is well described by the model of Ostwald-de Waale. It was determined that emulsion blocking mechanism is due to the presence of inclusions not emulsion viscosity.

scholarly journals Kinked Bisamides as Efficient Supramolecular Foam Cell Nucleating Agents for Low-Density Polystyrene Foams with Homogeneous Microcellular Morphology

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1094
Author(s):  
Bastian Klose ◽  
Daniel Kremer ◽  
Merve Aksit ◽  
Kasper P. van der Zwan ◽  
Klaus Kreger ◽  
...  
Keyword(s):  
Cell Size ◽  
Self Assembly ◽  
Large Scale ◽  
Elevated Temperatures ◽  
Foam Cell ◽  
Cell Structure ◽  
Expansion Ratio ◽  
Low Density ◽  
Nucleating Agents ◽  
Foam Density

Polystyrene foams have become more and more important owing to their lightweight potential and their insulation properties. Progress in this field is expected to be realized by foams featuring a microcellular morphology. However, large-scale processing of low-density foams with a closed-cell structure and volume expansion ratio of larger than 10, exhibiting a homogenous morphology with a mean cell size of approximately 10 µm, remains challenging. Here, we report on a series of 4,4′-diphenylmethane substituted bisamides, which we refer to as kinked bisamides, acting as efficient supramolecular foam cell nucleating agents for polystyrene. Self-assembly experiments from solution showed that these bisamides form supramolecular fibrillary or ribbon-like nanoobjects. These kinked bisamides can be dissolved at elevated temperatures in a large concentration range, forming dispersed nano-objects upon cooling. Batch foaming experiments using 1.0 wt.% of a selected kinked bisamide revealed that the mean cell size can be as low as 3.5 µm. To demonstrate the applicability of kinked bisamides in a high-throughput continuous foam process, we performed foam extrusion. Using 0.5 wt.% of a kinked bisamide yielded polymer foams with a foam density of 71 kg/m3 and a homogeneous microcellular morphology with cell sizes of ≈10 µm, which is two orders of magnitude lower compared to the neat polystyrene reference foam with a comparable foam density.

scholarly journals The coordination of ploidy and cell size differs between cell layers in leaves

Development ◽  
2016 ◽  
Vol 143 (7) ◽  
pp. 1120-1125 ◽  
Author(s):  
Yohei Katagiri ◽  
Junko Hasegawa ◽  
Ushio Fujikura ◽  
Rina Hoshino ◽  
Sachihiro Matsunaga ◽  
...  
Keyword(s):  
Cell Size ◽  
Cell Layers

scholarly journals Organismal view of a plant and a plant cell.

2001 ◽  
Vol 48 (2) ◽  
pp. 443-451 ◽  
Author(s):  
P Wojtaszek
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Cell Walls ◽  
Growth Time ◽  
Dead Cell ◽  
Plant Body ◽  
The Status ◽  
A Cell ◽  
Plant Form ◽  
Biological Organisation

Cell walls are at the basis of a structural, four-dimensional framework of plant form and growth time. Recent rapid progress of cell wall research has led to the situation where the old, long-lasting juxtaposition: "living" protoplast--"dead" cell wall, had to be dropped. Various attempts of re-interpretation cast, however, some doubts over the very nature of plant cell and the status of the walls within such a cell. Following a comparison of exocellular matrices of plants and animals, their position in relation to cells and organisms is analysed. A multitude of perspectives of the biological organisation of living beings is presented with particular attention paid to the cellular and organismal theories. Basic tenets and resulting corollaries of both theories are compared, and evolutionary and developmental implications are considered. Based on these data, "The Plant Body"--an organismal concept of plants and plant cells is described.

scholarly journals Secretion of Cryparin, a Fungal Hydrophobin

1999 ◽  
Vol 65 (12) ◽  
pp. 5431-5435 ◽  
Author(s):  
Patricia M. McCabe ◽  
Neal K. Van Alfen
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Submerged Culture ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Vesicle ◽  
Cryphonectria Parasitica ◽  
Secreted Protein ◽  
Filamentous Ascomycete ◽  
A Cell

ABSTRACT Cryparin is a cell-surface-associated hydrophobin of the filamentous ascomycete Cryphonectria parasitica. This protein contains a signal peptide that directs it to the vesicle-mediated secretory pathway. We detected a glycosylated form of cryparin in a secretory vesicle fraction, but secreted forms of this protein are not glycosylated. This glycosylation occurred in the proprotein region, which is cleaved during maturation by a Kex2-like serine protease, leaving a mature form of cryparin that could be isolated from both the cell wall and culture medium. Pulse-chase labeling experiments showed that cryparin was secreted through the cell wall, without being bound, into the culture medium. The secreted protein then binds to the cell walls ofC. parasitica, where it remains. Binding of cryparin to the cell wall occurred in submerged culture, presumably because of the lectin-like properties unique to this hydrophobin. Thus, the binding of this hydrophobin to the cell wall is different from that of other hydrophobins which are reported to require a hydrophobic-hydrophilic interface for assembly.

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