Lamellar Crystalline Structure Research Articles

Canine transmissible venereal sarcoma: electron microscopic changes with time after transplantation.

The structure of canine transmissible venereal sarcoma (CTVS) has been examined from 14 to 71 days after implantation. During early growth, the tumour appears to be composed primarily of loosely arranged, round cells and a few fibroblast-like cells. As the tumour mass increases, the round cells become tightly packed with highly interdigitating plasma membranes. The number of irregularly shaped round cells and fibroblast-like cells increases with increasing tumour mass. Collagen and reticular fibres can be found in early tumours, frequently in association with the round cells, and in regions devoid of fibroblast-like cells. During tumour regression, cellular degradation is evident in fibroblast-like and irregularly shaped cells as well as round cells. The data suggest that transformation may occur in the course of tumour growth, causing morphological change from round to fibroblast-like cells, and that CTVS is an undifferentiated round-cell sarcoma capable of differentiation in a fibroblastic direction. Also present, primarily in tumour cells from newborn dogs, are cytoplasmic lamellar arrays and crystalline virus-like structures, both previously described in other forms of tumor cells.

Influence of the nature of the solvent on the lamellar crystalline structure of block copolymers with an amorphous block and a crystallizable poly(ethylene oxide) block

AbstractBlock copolymers of styrene and ethylene oxide, (SEO), and of butadiene and ethylene oxide, (BEO), in the presence of a preferential solvent of the amorphous block exhibit always a lamellar structure (LC) with crystallized and folded poly(ethylene oxide) chains at temperatures below about 50°C.To precise the influence of the nature of the solvent on the refolding of the poly(ethylene oxide) chains (PEO), we have studied by X‐ray diffraction and differential scanning calorimetry the LC structure of the copolymers BEO and SEO in the presence of different solvents for the amorphous block. The copolymers SEO were studied in the presence of xylene, toluene and diethyl phthalate. Diethyl phthalate being a bad solvent for polybutadiene, the copolymers BEO were studied only in the solvents xylene and toluene.The influence of the nature of the solvent on the extent of the domain where the LC structure exists, on the refolding, and on the crystallinity of the poly(ethylene oxide) blocks is demonstrated.

Structural study of polybutadiene‐poly(ethylene oxide) block copolymers. Influence of the nature of the amorphous block on the refolding of the poly(ethylene oxide) chains

AbstractOur earlier studies on block copolymers polystyrene‐poly(ethylene oxide) has allowed to state the influence of the molecular weight of the copolymer and of its composition on the refolding of the crystallized poly(ethylene oxide) chains. To precise the effect of the nature of the amorphous block, we have studied by X‐ray diffraction and differential scanning calorimetry, the lamellar crystalline structures exhibited by block copolymers polybutadiene‐poly(ethylene oxide) (BEO) in the presence of a preferential solvent of one block: xylene for polybutadiene (PB), acetic acid or acrylic acid for poly(ethylene oxide) (PEO). In systems BEO copolymer/preferential solvent of PEO, the lamellar structure with crystallized PEO chains (LCC) exists at temperatures below about 45°C and for solvent concentrations ranging from 0 to a value characteristic of the copolymer. In the LCC structure, the chains of PEO crystallize in two layers; the solvent forms a third layer located between the PEO layers. We have studied the influence of the nature of the amorphous block on the variation of the structural parameters with the solvent concentration. In systems BEO copolymer/preferential solvent of PB, the lamellar structure with crystallized PEO chains (LC) appears at temperatures below about 50°C and for all solvent concentrations where the mesophase exists. In the LC structure, the chains of PEO crystallize folding in two superposed layers. We have established the influence of the solvent concentration and the nature of the amorphous block on the number of folds and the crystallinity of the PEO chains.

Histophathology and electron microscopy of channel catfish virus in infected channel catfish, Ictalurus punctatus (Rafinesque)*

A histologic and electron microscopic study was made on selected organs from channel catfish Ictalurus punctatus (Rafinesque) fingerlings that were experimentally infected with channel catfish virus (CCV). Histopathology was characterized by necrosis and haemorrhage in kidney and liver, and haemorrhage in the spleen and gastrointestinal tract. Virus replication occurred in nuclei of cells in the kidney, liver and spleen. Intranuclear inclusion bodies consisting of geometric crystalline arrays and lamellar structures were associated with virus replication.

人骨髄肥絆細胞の電子顕微鏡的研究

Mast cells obtained from human bone marrow have been studied by an electron microscope. The cells are usually round or oval and contain a nucleus possessed features typical of nuclei in most other cells. There are one or more nucleoli within the nucleus and the dense chromatin blocks usually attach to the inner nuclear membrane. The Golgi complex is frequently located at or around the indentation of the nucleus. Mitochondria, round on oval in profile, contain a few cristae. Microvilli are observed on the surface of the cell membrane. There are a number of specific granules in the cytoplasm of the cells, which are usually round in shape,0.5-0.7μ in diameter, and surrounded by a limiting membrane. Within the granules five kinds of structures have been observed; (1) homogeneous structure, (2) granular structure, (3) scroll structure, (4) lamellar crystalline structure, and (5)hexagonal crystalline structure. Sometimes a number of vacuoles are observed within the cytoplasm. Some of the specific granules are in close contact or in fusion with the vacuoles.

The nature of the lamellar crystalline structure in branched polyethylenes as deduced from melting point and branching determinations

AbstractIn a semicrystalline polymer chain, if n is the total number of backbone units and a is the number of nonlattice backbone units, then the per cent crystallinity is (n – a)/n. By an empirical approach it is found that if a is set equal to ca. 40 for branched polyethylenes and n is determined from a melting point‐fold length relationship that the calculated values of per cent crystallinity are in good agreement with experiment. It is also shown that 100/(n – a) is equivalent to the total number of branches per 100 methylenes for branched polyethylene. A sinusoidal random coil is postulated for the melt state in order to rationalize why chain folding with adjacent reentry should occur if as many as 40 methylenes per fold are noncrystalline.