Morphological Studies of Solution‐Crystallized Thermoplastic Elastomers with Polyethylene Endblocks and a Random‐Copolymer Midblock

Abstract The morphology development of dynamically vulcanized thermoplastic elastomers (TPVs) based on EPDM/PP in a modular intermeshing co-rotating twin screw extruder was studied. Effects of the blend composition and screw speed were considered. The morphological studies were carried out on the cryogenically fractured surface of the samples using Scanning Electron Microscopy (SEM) technique. The flow behavior and melt viscoelastic properties of the samples were also investigated by using Rheometric Mechanical Spectrometer (RMS). The SEM results from TPV samples produced in the twin screw extruder showed a matrix-disperse type morphology similar to those reported for the TPV samples prepared in an internal mixer. The dynamic vulcanization process imposed on the molten blends resulted in a remarkable increase in the steady state torque of the extruder whose extent was found to be dependent upon the EPDM content and screw speed. These results were explained in terms of an agglomerate structure formed between the cured rubber particles. The TPV samples, in particular the samples containing 60% of EPDM, showed a pronounced viscosity upturn and strong elastic modulus (G′) at low frequency range. It was demonstrated that these results in conjunction with the results of relaxation time distribution H(λ) of the samples can provide a great insight into understanding the role of the blend composition and the processing variables on morphology development in the TPV samples in the co-rotating twin screw extruder.

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Fine Structural Localization of Acyltransferases Involved in Lipid Synthesis in Intestinal Mucosa.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067261 ◽

1970 ◽

Vol 28 ◽

pp. 54-55

Author(s):

R. J. Barrnett ◽

J. A. Higgins

Keyword(s):

Smooth Endoplasmic Reticulum ◽

Lipid Synthesis ◽

Mucosal Cell ◽

Structural Localization ◽

Morphological Studies ◽

Mucosal Cells ◽

Initial Appearance ◽

Sh Group ◽

Hydrolysis Of ◽

Intestinal Mucosal Cells

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.

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Chromic Acid Etching of Polyethylene

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070801 ◽

1973 ◽

Vol 31 ◽

pp. 72-73

Author(s):

J. D. Muzzy ◽

R. D. Hester ◽

J. L. Hubbard

Keyword(s):

Chromic Acid ◽

Low Cost ◽

Acid Etching ◽

Crystalline Morphology ◽

Bulk Specimen ◽

Morphological Studies ◽

Perfect Form ◽

Molecular Length ◽

Lamellar Texture ◽

Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

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Biological and Morphological Studies on Low-Leukemia-Strain Mice with Hodgkin's-Like Neoplasia Induced by Serial Cell-Free Transmission of Leukemic Organs of SJL/J Strain Mice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100792 ◽

1968 ◽

Vol 26 ◽

pp. 210-211

Author(s):

S. Fujinaga ◽

K. Maruyama ◽

C.W. Williams ◽

K. Sekhri ◽

L. Dmochowski

Keyword(s):

Tissue Culture ◽

Type A ◽

Reticulum Cell ◽

Type B ◽

Viral Origin ◽

Serial Transfer ◽

Strain Mouse ◽

Morphological Studies ◽

Cell Neoplasm ◽

Free Material

Yumoto and Dmochowski (Cancer Res.27, 2098 (1967)) reported the presence of mature and immature type C leukemia virus particles in leukemic organs and tissues such as lymph nodes, spleen, thymus, liver, and kidneys of SJL/J strain mice with Hodgki's-like disease or reticulum cell neoplasm (type B). In an attempt to ascertain the possibility that this neoplasia may be of viral origin, experiments with induction and transmission of this neoplasm were carried out using cell-free extracts of leukemic organs from an SJL/J strain mouse with spontaneous disease.It has been possible to induce the disease in low-leukemia BALB/c and C3HZB strain mice and serially transfer the neoplasia by cell-free extracts of leukemic organs of these mice. Histological examination revealed the neoplasia to be of either reticulum cell-type A or type B. Serial transfer is now in its fifth passage. In addition leukemic spleen from another SJL/J strain mouse with spontaneous reticulum cell neoplasm (type A) was set up in tissue culture and is now in its 141st serial passage in vitro. Preliminary results indicate that cell-free material of 39th tissue culture passage can reproduce neoplasia in BALB/c mice.

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Morphological studies of linear (AB)n multiblock copolymers and their blends

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122320 ◽

1992 ◽

Vol 50 (1) ◽

pp. 384-385

Author(s):

Richard J. Spontak ◽

Steven D. Smith ◽

Arman Ashraf

Keyword(s):

Electron Microscopy ◽

Microphase Separation ◽

Multiblock Copolymers ◽

First Order ◽

Morphological Studies ◽

Transmission Electron ◽

First Order Phase Transition ◽

Covalently Bonded ◽

Total Molecular Weight ◽

First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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Mast cell-nerve fiber interaction: Ultrastructural studies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159680 ◽

1990 ◽

Vol 48 (3) ◽

pp. 428-429

Author(s):

E.Y. Chi ◽

M.L. Su ◽

Y.T. Tien ◽

W.R. Henderson

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Substance P ◽

Nerve Fiber ◽

Sensory Nerves ◽

Ultrastructural Studies ◽

Morphological Studies ◽

Granulocyte Infiltration ◽

Intracutaneous Injection ◽

Recent Attention

Recent attention has been directed to the interaction of the nerve and immune systems. The neuropeptide substance P, a tachykinnin which is a neurotransmitter in the central and peripheral nervous systems produces tissue swelling, augemntation of intersitial fibrin deposition and leukocyte infiltration after intracutaneous injection. There is a direct correlation reported between the extent of mast cell degranulation at the sites of injection and the tissue swelling or granulocyte infiltration. It has previously been demonstrated that antidromic electrical stimulation of sensory nerves induces degranulation of cutaneous mast cells, cutaneous vasodilation and augmented vascular permeability. Morphological studies have documented a close anatiomical association between mast cells and nonmyelinated nerves, that contain substance P and other neuropeptides. However, the presence of mast cells within nerve fasicles has not been previously examined ultrastructurally. In this study, we examined ultrastructurally the distribution of mast cells in the nerve fiber bundles located in the muscular connective tissue of rat tongues (n=20).

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Histochemical and Ultrastructural Studies of the Digestive Epithelium in a Gastropod Gametolytic Organ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s143192760000252x ◽

1980 ◽

Vol 38 ◽

pp. 568-569

Author(s):

R. L. Reeder ◽

S. H. Rogers ◽

W. A. Shannon

Keyword(s):

Acid Phosphatase ◽

Genital Tract ◽

Reproductive Tract ◽

Ultrastructural Level ◽

Conclusive Evidence ◽

Digestive Organ ◽

Limited Information ◽

Ultrastructural Studies ◽

Morphological Studies

Numerous morphological studies have dealt with the spermatheca of pulmonate gastropods. This globular organ, which is attached to the female portion of the reproductive tract by a long duct in these monoecious animals, has had various functions ascribed to it. Recent histochemical demonstrations of deoxyribonuclease, ribonuclease, protease, and acid phosphatase have provided, however, conclusive evidence that it is a digestive organ for the degradation of superfluous sperm and genital tract secretions. Only limited information concerning the spermatheca is available at the ultrastructural level, a fact providing the stimulus for the present study of this organ in Sonorella santaritana, a desert mountain snail from Arizona.

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Limnological characteristics, community metabolism and management strategies of a coastal sinkhole in Cuba (Cenote Jennifer)

Annales de Limnologie - International Journal of Limnology ◽

10.1051/limn/2020022 ◽

2020 ◽

Vol 56 ◽

pp. 24

Author(s):

Roberto González-De Zayas ◽

Liosban Lantigua Ponce de León ◽

Liezel Guerra Rodríguez ◽

Felipe Matos Pupo ◽

Leslie Hernández-Fernández

Keyword(s):

Hydrogen Sulfide ◽

Primary Productivity ◽

Major Ions ◽

Saline Water ◽

Management Strategies ◽

Tourist Destination ◽

Community Metabolism ◽

Morphological Studies ◽

Made In ◽

Limnological Parameters

The Cenote Jennifer is an important and unique aquatic sinkhole in Cayo Coco (Jardines del Rey Tourist Destination) that has brackish to saline water. Two samplings were made in 1998 and 2009, and 4 metabolism community experiments in 2009. Some limnological parameters were measured in both samplings (temperature, salinity, pH, dissolved oxygen major ions, hydrogen sulfide, nutrients and others). Community metabolism was measured through incubated oxygen concentration in clear and dark oxygen bottles. Results showed that the sinkhole limnology depends on rainfall and light incidence year, with some stratification episodes, due to halocline or oxycline presence, rather than thermocline. The sinkhole water was oligotrophic (total nitrogen of 41.5 ± 22.2 μmol l−1 and total phosphorus of 0.3 ± 0.2 μmol l−1) and with low productivity (gross primary productivity of 63.0 mg C m−2 d−1). Anoxia and hypoxia were present at the bottom with higher levels of hydrogen sulfide, lower pH and restricted influence of the adjacent sea (2 km away). To protect the Cenote Jennifer, tourist exploitation should be avoided and more resources to ecological and morphological studies should be allocated, and eventually use this aquatic system only for specialized diving. For conservation purposes, illegal garbage disposal in the surrounding forest should end.

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ESTIMATION OF EFFICIENCY OF COLLAGEN AND BIOLOGICAL GLUE AT DUODENAL FISTULA IN EXPERIMENT

Creative Surgery and Oncology ◽

10.24060/2076-3093-2018-8-1-69-75 ◽

2018 ◽

Vol 8 (1) ◽

pp. 69-75

Author(s):

R. R. Ishtukov ◽

M. A. Nartailakov ◽

V. S. Panteleev ◽

V. V. Rezyapov

Keyword(s):

Intestinal Tract ◽

Histological Study ◽

Abdominal Cavity ◽

Suture Line ◽

Intestinal Fistula ◽

Duodenal Fistula ◽

Morphological Studies ◽

Vascular Congestion ◽

Dermal Collagen ◽

Surgical Tactics

Introduction. One of the worst complication of different surgical diseases of abdominal cavity organs and of performed, on that regard, operational interventions, are intestinal festulas including without limitation deodenum fistulas. Longterm experience of surgical treatment of patients with unformed duodenal and high enteric fistulas show that it is feasible to have a clear surgical tactics with account of location level and type of fistulas, their quantity, volume of sarcous reduction, peritonitis and multi-organ failure syndrome. In this regard, the objective of this research is to find optimal surgical tactics and to determine the most effective method of treating duodenum fistulas of various causation.Materials and methods. Experimental work was carried out under conditions of experimentally formed intestinal fistula in rabbits of “Shinshilla” breed. After formation of fistula the animals were divided into 3 groups based on the method of removing artificially installed duodenal fistula: sealing through Albert — Schmieden — Lembert suture without fastening of suture line; sealing through fastening of intestinal suture with biological surgical glue; sealing through fastening with swine dermal collagen. Mechanical constancy of the sutures was measured with pneumocompression of sealed intestinal tract areas as well as with morphological study of surgical wound edges.Results. The results of histological study show that experiments with application of bio-implant demonstrated less vascular congestion and interstitial swelling. Phologistic infiltration also responded more efficiently both quantitatively (manifestation rate) and qualitatively (quick change of cell elements) in the group that used bio-implant.Conclusion. Results of morphological studies and pneumocompression data under modelling of duodenal fistulas in experimental animals show that application of bio-implant helps to earlier restore microcirculatory abnormality.

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