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At least 505 records · Page 28Linked to original sources
PubMed2001

Development of the fiber neutron monitor for the energy range 15-100 MeV on the International Space Station (ISS).

In order to investigate the space environment, a new neutron monitor has been prepared. The sensor consists of scintillation fibers (FIB) and will be on board the exposed facility of the Japanese Experimental module (Kibo) of the International Space Station (ISS). The sensor is one of the instruments which measures the particle and plasma environment around the ISS. The sensor will be used by the cosmonauts who work on the ISS, to help them avoid a strong particle radiation which may arrive soon. We believe that such an alert is necessary for the cosmonauts to prevent unnecessary radiation from the sun. Furthermore, the sensor will be very useful in understanding the particle acceleration mechanism at the solar surface. The design of the Engineering Model (EM) was finished and its properties were investigated. This report discusses these results.

Equipment Design↗
PubMed2001

Effect of loading on the development of nerve fibers around oral implants in the dog mandible.

Occlusal forces cause stress which morphologically affects the supporting tissues of implants. The aim of this study was to examine the effects of occlusal forces on the distribution of neurofilament protein (NFP)-positive nerve fibers in the tissue of peri-implant bone. The bilateral 2nd, 3rd and 4th mandibular premolars and the 1st molars were extracted from three mongrel dogs. After 4 months of healing, 4 screw-type implants were inserted in the oral cavity. Three months after insertion, the implants on the molar site were loaded by occlusal forces, while those on the premolar site were unloaded. After a further 3 months, the dogs were sacrificed, and specimens were prepared for immunohistochemical NFP-positive staining by the labeled-streptavidin-biotin method. Many NFP-positive nerve fibers were found in the tissues of the loaded site when compared with the unloaded site. These fibers were localized in both the bone marrow space and in the peri-implant fibrous tissue. They had two types of nerve endings: simple free nerve endings, and nerve endings with tree-like ramifications. The present results suggest that loading by occlusal force causes an increase in the number of NFP-positive nerve fibers, many of which have free nerve endings in the peri-implant tissue. The possible role of these NFP-positive nerve fibers is discussed.

Alloys↗
PubMed2003

Development of silicone rubber hollow fiber membrane oxygenator for ECMO.

Silicone rubber hollow fiber membrane produces an ideal gas exchange for long-term ECMO due to nonporous characteristics. The extracapillary type silicone rubber ECMO oxygenator having an ultrathin hollow fiber membrane was developed for pediatric application. The test modules were compared to conventional silicone coil-type ECMO modules. In vitro experiments demonstrated a higher O2 and CO2 transfer rate, lower blood flow resistance, and less hemolysis than the conventional silicone coil-type modules. This oxygenator was combined with the Gyro C1E3 centrifugal pump, and three ex vivo experiments were conducted to simulate pediatric V-A ECMO condition. Four day and 6 day experiments were conducted in cases 1 and 2, respectively. Case 3 was a long-term experiment up to 2 weeks. No plasma leakage and stable gas performances were achieved. The plasma free hemoglobin was maintained within a normal range. This compact pump-oxygenator system in conjunction with the Gyro C1E3 centrifugal pump has potential for a hybrid total ECMO system.

Animals↗
PubMed2003

Modeling the retention and clearance of manmade vitreous fibers in the rat lung.

A mathematical model describing the dissolution and disintegration of long fibers and the clearance of short fibers is developed. For short fiber clearance, the model is based on previous modeling of the retention and clearance of particles, and most model parameters are taken from that particulate model. In addition to modeling the disappearance of long fibers, the present study includes a quantitative measure of goodness of fit of the model to observed data. Data from chronic inhalation experiments with insulation glass wools (MMVF10 and MMVF11) and rockwool (MMVF21) were provided for this study. These data comprised lung burdens at 10 time points at each of 3 concentrations for each fiber in inhalation experiments lasting up to 104 wk. At the two higher concentrations, the model had to take into account the effects of lung burden on macrophage-mediated clearance. The modeling shows that the overload dependence appears remarkably similar to that for low-toxicity particles in that the critical volumetric lung burden is similar to that for low toxicity dust. The model describes overload as leading to alveolar sequestration of short fibers or particles, and the estimated rate of alveolar sequestration for MMVF10 was similar to that for particles, but the estimated rate was lower for the other two fibers. Two alternative hypotheses to describe the process of the disappearance of longer fibers were tested by assessing their effect on a quantitative measure of fit of model predictions to the lung-burden data. These tests indicated that (a) dissolution leading to disintegration of long fibers into shorter fibers gave a much better fit than the alternative assumption that dissolution would leave only nonfibrous residue and (b) the relative rates of disintegration of the fibers in the lung appear to be directly dependent on their rates of in vitro dissolution and their diameters.

Administration, Inhalation↗
PubMed1980

Progressive somatofugal activation of cerebroside sulfotransferase in the developing chick optic fibers.

A myelination parameter of the chick optic pathway has been investigated: the activity of cerebroside sulfotransferase. Evidence is presented for a somatofugal progression of the enzyme activity peak along the optic nerve, chiasm, optic tract, tectum anterior, and tectum posterior. The enzyme activity appears on the fifteenth embryonic day and reaches a maximum in the nerve two days before hatching. One day after hatching, the peak is found in the chiasm, and three days after that in the optic tract. The peak is found in the tectum anterior on the tenth day. The results suggest a somatofugal progression of myelination.

Animals↗
PubMed1999

Development of afferent fiber lamination in the infrapyramidal blade of the rat dentate gyrus.

In the rat dentate gyrus, the lateral perforant path, the medial perforant path, and the major part of the hilar projection to the molecular layer share the lamination domain, mainly in the outer one-third of the molecular layer, the middle one-third, and the inner one-third, respectively. To reveal the order of the afferent fiber lamination and to have an indication of how the synaptic sites on dendrites are determined, we investigated the ontogeny of afferent fiber lamination in the dorsal hippocampus by injecting 1, 1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) into the entorhinal cortex and hippocampus in vivo. Fibers from the contralateral hilar region were found under the pia mater of the infrapyramidal blade at postnatal day 3 (P3), whereas the entorhinal afferent fibers were absent in the infrapyramidal blade. Then the medial and the lateral perforant path appeared under the pia mater in the infrapyramidal blade as riding on top of the preexisting laminae by P7 and by P11, respectively. Based on the established knowledge that most entorhinal layer II neurons simultaneously innervate both the suprapyramidal blade and infrapyramidal blade by branching, it is assumed that the medial and lateral perforant path in the suprapyramidal blade await an appropriate timing for sprouting of interstitial branches into the infrapyramidal blade. The granule cells in the infrapyramidal blade had dendritic growth cones by P11. Calretinin immunohistochemistry revealed Cajal-Retzius cells in the infrapyramidal blade even at P14. Under the pia mater, axon growth cones of ingrowing afferent fibers may interact with the dendritic growth cones or the Cajal-Retzius cells, and determines the synaptic sites on the granule cell dendrites.

Afferent Pathways↗
PubMed2000

The future of lasers in dentistry.

In 1998, a laser-related trade journal printed an article on laser dermatology indicating that because of new applications, reduced prices, and instruments becoming more user-friendly, the dermatology laser market was becoming a billion dollar industry. If the same holds true in dentistry--keeping in mind that there are only approximately 7000 dermatologists in the United States--think of the potential for the dental laser market. It is huge, but to reach that potential, several criteria must be met: Market penetration must double in the next 4 to 5 years. Instrument sizes must diminish. Laser prices must decrease to an average of $10,000 for soft tissue lasers and $25,000 for hard tissue lasers over the next 10 years. Meeting these criteria would generate the necessary revenues for increased expenditures for research and development to improve existing delivery systems and develop new fiber types, continue development of a short-pulsed hard tissue laser to replace air turbines, and combine wavelengths into a single package, while looking into new wavelengths. If all of the above-mentioned become a reality in 10 to 15 years, the growth of the dental laser market could be limitless because of the hugeness of the worldwide dental marketplace. The last 20 years have witnessed many new developments in dental technologies, and the next 20 years promise to be even richer in technologic advancements. Lasers will be in the forefront of that growth.

Dental Equipment↗