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  • 1
    Electronic Resource
    Electronic Resource
    A study of the myenteric plexus of the congenital aganglionosis rat (spotting lethal) (1985)
    Springer
    Anatomy and embryology 171 (1985), S. 285-296 
    Details
    ISSN: 1432-0568
    Keywords: Congenital aganglionosis ; Myenteric plexus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The entire bowel of a mutant strain of rats, the congenital aganglionosis rat (spotting lethal), was investigated using the acetylcholinesterase reaction and immunohistochemical staining for tyrosine hydroxylase and substance P in whole-mount preparations. The histology of the bowel of mutant rats was also studied by light- and electron microscopy. In all examined mutant rats, a constricted region of intestine followed a dilated region of the bowel. In 29 cases constricted segments extended from rectum to distal ileum; in 3 cases from rectum to middle colon. In controls the myenteric plexus appeared as a mesh-work consisting of ganglion strands and internodal strands, showing a rather regular ladder-like pattern from duodenum to rectum. The myenteric plexus of mutants was very different from that of controls, showing conspicuous regional differences. Even in the duodenum, where there was no macroscopical disorder, the plexus showed an irregular pattern, the meshes varying greatly in size and shape. Ganglion strands were shorter than those in controls. The plexus in the dilated segment gradually decreased in density, finally disappearing above the proximal terminal of the constricted segment. In some areas, below this transition, i.e., the anal portion of the constricted segment in 29 cases (long constricted segment type only), there were neither ganglion cells nor nerve fibers except for scarcely distributed tyrosine hydroxylase-immunoreactive nerve fibers. In the distal part of the upper colon some fine nerve bundles, gradually increased in number and mixed with thicker nerve bundles in the lower portion of the colon. Finally, at the level of the rectum, nerve bundles of various sizes interlaced irregularly with one another to form a network. However, this network was free from ganglion cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347017
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  • 2
    Electronic Resource
    Electronic Resource
    Post-anodization filtered illumination of porous silicon in HF solutions: An effective method to improve luminescence properties (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1656-1658 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A useful method is presented to improve the luminescence efficiency of porous silicon (PS) based on the post-anodization illumination of samples in HF solutions. In the present method the illumination is performed by a white lamp through sharp-cut long-wavelength-pass filters to remove the short wavelength component from the illumination light. The PS samples prepared by this method exhibited the visible photoluminescence (PL) with an efficiency of one order of magnitude higher than those illuminated without filters. The efficiency improvement is attributed to the reduction of the deteriorative surface oxidation of Si crystallites in PS. The filtered illumination technique is also useful to produce a larger PL blue shift and precise control of PL spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112946
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  • 3
    Electronic Resource
    Electronic Resource
    Photoelectronic properties of porous silicon (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1986-1988 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that the introduction of a porous structure into single-crystal Si produces substantial changes in the photoelectronic properties. The porous Si (PS) layer is formed by anodization of p-type Si wafers in a HF solution. The photoconduction cells used in this study consists of a semitransparent thin Au film, PS, Si substrate, and Al ohmic contact. The photoconductive behavior of PS is characterized by an extremely high dark resistivity, a definite photosensitivity for visible light, and an intrinsic bias voltage dependence of the spectral response. These properties, which are interpreted to be the result of a band-gap widening in PS, provide further support of the assumption that the visible luminescence of PS is explained by the band scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357663
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of the visible electroluminescence from metal/porous silicon/n-Si devices (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 1407-1412 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The excitation and radiative recombination mechanisms of carriers in electroluminescent porous silicon (PS) have been studied for the device with the structure of Au/PS/n-type Si. Experiments focus on the electroluminescence (EL) and photoluminescence (PL) spectra, the current-voltage-EL intensity relationship and its temperature dependence, and the excitation-wavelength dependence of the electric-field-induced PL quenching. The results of these experiments suggest the following points: (1) the EL occurs mainly near the Au/PS contact; (2) there exists an extremely high electric field at the Au/PS contact; (3) the EL originates from radiative recombination of strongly localized excitons; and (4) the radiative recombination rate is in proportion to the diode current. Based on these observations, an operation model is proposed. In our model, a large number of electrons and holes are generated in the PS layer by a field-assisted mechanism. Light emission occurs by radiative recombination of these electrons and holes via localized states. Because of field-enhanced carrier separation, however, the EL efficiency of this device is limited to a relatively low value of about 0.05%. Possible ways to improve the EL characteristics are discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363878
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of gastrin-releasing peptide (GRP) on guinea pig gallbladder contrction in vitro (1995)
    Springer
    Journal of gastroenterology 30 (1995), S. 764-767 
    Details
    ISSN: 1435-5922
    Keywords: acetylcholine (Ach) ; cholecystolinin octapeptide (CCK8) ; gastrin-releasing peptide (GRP) ; atropine ; loxiglumide ; gallbladder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Few studies have reported the effects of gastrin-releasing peptide (GRP)/bombesin on the guineas pig gallbladder, and the results are contradictory. Because such contradictory results may, in part, be due to technical factors, we investigated the effect of GRP on guinea pig gallbaladder smooth muscle, using a improved horizontal organ bath. The guinea pigs were killed and the gallbladder was removed. Four longitudinal uscle strips (2×12mm) were suspended in Krebs-Ringer solution at 37°C and aerated with 95% O2 and 5% CO2. The mechanical activity of the strips was recorded isotonically by displacement-voltage transducers. via L-arms, to which a piezoelectric element with a frequency of 100Hz and movement of 50μm was applied. GRP contracted gallbladder muscle strips dose dependently, but the calculated maximal response was 22.4% and 20.1% of the acetylcholine-and cholecystokinin octapeptide (CCK8)-induced responses, respectively. The GRP-induced contraction was unaffected by the muscarinic blocker, atropine, or by the CCK receptor antagonist, loxiglumide. It is concluded that GRP weakly, but apparently directly, stimulates guinea pig gallbladder contraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02349644
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  • 6
    Electronic Resource
    Electronic Resource
    Simultaneous localization of acetylcholinesterase activity and met-enkephalin, vasoactive intestinal peptide and substance P immunoreactivity in the rat myenteric plexu (1988)
    Springer
    Journal of molecular histology 20 (1988), S. 464-467 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01002433
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  • 7
    Electronic Resource
    Electronic Resource
    Role of peptide YY in regulation of duodenal motility during the interdigestive period in sheep (1997)
    Springer
    Journal of comparative physiology 167 (1997), S. 352-360 
    Details
    ISSN: 1432-136X
    Keywords: Key words PYY ; Rumen ; Duodenum ; MMC ; Exocrine pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Temporal coordination between duodenal migrating myoelectric complexes (MMC) and pancreatic exocrine secretion, and the effects of porcine peptide YY (PYY) on gastroduodenal motility and pancreatic exocrine secretion were examined during the interdigestive period in conscious mature sheep. Fluid and enzyme secretions from the exocrine pancreas showed a periodic pattern corresponding to the phases of duodenal MMC, although these secretion rates were maintained at a high level during phase II in sheep. Intravenous continuous infusion of PYY at doses ranging from 50 to 200 pmol · kg−1 · h−1 or intravenous bolus infusion of PYY at doses ranging from 50 to 200 pmol · kg−1 showed a tendency to prolong the first cycle of the duodenal MMC and significantly shorten the second cycle. However, there was almost no effect on ruminal contractions from the PYY administration. In the pancreatic exocrine secretion, PYY could inhibit only bicarbonate secretion at only the highest dose of 200 pmol · kg−1. These results imply that endogenous PYY may play a physiological role in the regulation of the duodenal MMC cycles in sheep but not in ruminal contractions. PYY seems unlikely to regulate the pancreatic exocrine secretion in normal sheep, because a supraphysiological dose of PYY was required to inhibit the pancreatic exocrine secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050084
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