Range Of Fiber Diameters Research Articles

MYOPATHY WITH MINICORES IN SIBLINGS

Myopathy with minicores in siblingsA muscle biopsy from a 5 year old boy with a myopathic disorder showed a wide range of fibre diameters, Type 1 fibre predominance and focal loss of ‘ATPase’ activity in some fibres. Electron microscopy showed, in about 10% of fibres, localized distortions and loss of Z‐lines within compactly grouped myofibrils with preservation of glycogen and mitochondria. His younger sibling, aged 1 year, who was only mildly hypotonic, showed similar but less marked abnormalities on muscle biopsy. These changes are those described in ‘multicore disease’, but it is suggested that the term ‘minicore’ might be more appropriate to avoid confusion with central core disease in which multiple cores are often found. Because of the preservation of mitochondria and glycogen, and the slightly atypical staining of Type 1 fibres it is suggested that the disorder might be caused by an abnormality of myosin or actin.

Microwave Shielding Properties of Thin Stainless Steel Needles Embedded in Rubber

AbstractThe S- and X-band shielding properties (SE = shielding effectiveness; R = reflection loss; A = absorption loss) of mixtures of silicon rubber and metal fibres have been investigated for a wide range of fibre length, fibre diameter and fibre concentration. Data are given which allow the design of materials with specified shielding properties.

Ultrastructure of visual callosal axons in the rabbit

This study examines the morphology of visual callosal axons in the adult rabbit. Axons in the posterior 3 mm of the splenium of the corpus callosum were examined by electron microscopy. Nonmyelinated fibers comprise approximately 45% of the fiber population. These axons range from 0.08 to 0.6 μm in diameter, and usually occur in clusters of at least three to four axons. Myelinated fibers comprise 55% of the axons in the splenium. The diameters of myelinated fibers range from 0.3 to 1.85 μm. Values of the ratio g (axon diameter: total fiber diameter) range from 0.64 to 0.87. In the majority of myelinated axons, the inner mesaxon and outer tongue of glial cytoplasm are located in the same quadrant. The nonmyelinated gap at the nodes of Ranvier extends less than 2 μm, and an electron-dense undercoating is present subjacent to the axon membrane at the node. Branching of fibers was not observed. A physiological analysis of the conduction properties of these axons is presented in the following paper.

Electron-microscopic observations on preterminal fibers in the oculomotor nucleus of the cat: With special reference to the relation between axon diameter and myelin thickness in mammalian gray matter

Electron microscopy of myelinated fibers in main lateral cell groups of the cat oculomotor nucleus reveals the majority to have diameters of les than 3 μm, with more than one-half less than 1 μm in diameter. The values of the ratio g (axon diameter/total fiber diameter) range between 0.58 and 0.88, with a mean of 0.74. There is no definite relation between g and fiber diameter. The morphological data are consistent with physiological data on preterminal conduction velocities in the oculomotor nucleus, and extend the dimensional analysis of myelinated fibers in gray matter, which has previously been confined to lower vertebrates, to the mammalian central nervous system.

Caliber spectra of fibers in the fasciculus gracilis of the cat cervical spinal cord: a quantitative electron microscopic study.

In order to obtain a better understanding of the microscopic structure of the cat fasciculus gracilis, entire cross-sections of the fasciculus were examined with the electron microscope. Twenty-five thousand, two hundred and eighty-four fibers were encountered in one fasciculus. The fiber caliber spectra obtained from the study show that the fasciculus gracilis at cervical level has a unique fiber distribution pattern. The fiber diameters range from less than 1 mu to 15 mu, however, 97 percent of fibers have diameters less than 8 mu; and the majority of the fibers are in the 2-5 mu range.

Physical parameters of airborne asbestos fibres in various work environments-preliminary findings.

The results of a pilot investigation to describe the physical parameters, length, aspect ratio, mass and shape of airborne fibres in a variety of industries producing processing and handling chrysotile, amosite and crocidolite are described. Samples of airborne dust were collected on nucleopore membrane filters and examined by scanning electron microscopy. The diameters and lengths of airborne fibres collected during the dumping of raw amosite at an asbestos products plant were greater than those of fibres collected during the application of amosite insulation. Chrysotile fibres collected in the carding area of an asbestos textile plant also tended to have smaller diameters than fibres collected in the dryer and bagging areas of an asbestos mill. The measurements of fibre dimensions indicate that the degree of protection afforded a worker by optical counts using the membrane filter technique is likely to depend on variety of asbestos and stage of processing. Preliminary results are not in conflict with experimental data suggesting that asbestosis might be related to the mass of airborne dust and primary malignant mesothelial tumors to exposure to fibres in a specific range of fibre diameter and length.

High Strength Glass Fibre-Resin Composites

I have reported that the mean breaking stress of undamaged single fibres of borosilicate glass, tested in tension is consistent at 3.66 kN mm−2 over a wide range of fibre diameters, with little scatter1. Commercial glass fibre strand, consisting of a large number of fibres aligned in parallel array, fractures at a mean breaking stress of 1.04 kN mm−2; and the value is determined by the individual fibre diameter in the strand. Single fibres taken from such strand have a mean breaking stress of 1.73 kN mm−2. For both strand, and damaged fibres taken from the strand, the scatter in the results is large.

Physical analysis of the fleece of sheep for biological purposes. I. Actual and apparent cross-sectional areas of a staple of fleece wool under lateral compression

An investigation has been made of errors associated with calculations of the sum of the cross-sectional areas of fibres in a staple of wool from the apparent cross-sectional area of the staple when compressed in a slot. The general mechanism of the compression process has been elaborated, and the errors associated with various conditions suggested. The staple size mainly considered was about that coming from one square inch of skin. The range of mean fibre diameter was from 16 to 32 microns.