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  • 1
    Electronic Resource
    Electronic Resource
    MICRO-CRACK GROWTH AND LIFE PREDICTION OF A 1CrMoV STEEL UNDER AXIAL-TORSIONAL LOW CYCLE FATIGUE AT 550°C (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 17 (1994), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Micro-crack behaviour under axial and torsional loading at 550°C was observed by replica techniques. Cracking behaviour and micro-damage observations were correlated using several parameters that are based on equivalent strain parameters. From the observations, micro-cracking of the oxide films at the crack tip in the strain localized regions seems to be a dominant micromechanism of fatigue crack growth. The maximum principal strain has been identified as an important parameter in multiaxial fatigue at high temperature. A good correlation was obtained between the principal strain range and the crack growth rate. Finally, a life prediction method was proposed based on maximum crack length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1994.tb00215.x
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  • 2
    Electronic Resource
    Electronic Resource
    Small-angle X-ray scattering study of lamellar microdomains in a block copolymer (1991)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 24 (1991), S. 679-684 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Lamellar microdomains formed in the solvent-cast films of a poly[styrene-block-(ethylene-alt-propylene)] (SEP) diblock polymer were studied by small-angle X-ray scattering (SAXS). The SAXS profiles, displaying a series of peculiar scattering maxima which cannot be ascribed to the higher-order diffraction maxima from a regular lamellar spacing, were analyzed based on a model of the one-dimensional paracrystal with a preferential orientation. The results suggest that these maxima are due to higher-order scattering maxima from single lamellar microdomains. The maxima suggest that the relative standard deviation for the distribution of the polystyrene lamellar size is much smaller than that of the lamellar spacing, giving rise to a situation in which the oscillation of the particle factor with scattering vector h persists up to high h values while that of the lattice factor damps to unity at low h values. The SAXS result was interpreted as being due to a bending distortion of the polystyrene lamella with a smaller thickness and a narrower thickness distribution than those of the poly(ethylene-alt-propylene) lamella. A study by transmission electron microscopy tends to support this result.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889890012109
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  • 3
    Electronic Resource
    Electronic Resource
    Excitatory amino acidergic pathways and receptors in the basal ganglia (1991)
    Springer
    Amino acids 1 (1991), S. 339-350 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Glutamate ; Aspartate ; α-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid ; Kainate ; N-Methyl-D-asparate ; Striatum ; Pallidum ; Substantia nigra ; Subthalamic nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The striatum receives the majority of excitatory amino acidergic input to the basal ganglia from neocortical and allocortical sources. The subthalamic nucleus and the substantia nigra also receive excitatory amino acidergic inputs from neocortex. The subthalamic nucleus, which has prominent projections to the pallidum and nigra, is the only known intrinsic excitatory amino acidergic component of the basal ganglia. Possible excitatory amino acidergic inputs reach the basal ganglia from the intralaminar thalamic nuclei and the pedunculo-pontine nucleus. The striatum is richly endowed with all subtypes of excitatory amino acid receptors and these appear to be inhomogeneously distributed within the striatal complex. The non-striatal nuclei contain lesser levels of excitatory amino acid receptors and the relative proportion of these receptors varies between nuclei. The presence of high densities of excitatory amino acid receptors is a phylogenetically conserved feature of the striatum and its non-mammalian homologues. In Huntington's disease, there is substantial depletion ofα-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, N-methyl-D-aspartate, and kainate receptors within the striatum. In Parkinson's disease substantia nigra, there is significant loss of N-methyl-D-aspartate andα-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00814003
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  • 4
    Electronic Resource
    Electronic Resource
    Book review (1994)
    Springer
    Rock mechanics and rock engineering 27 (1994), S. 262-263 
    Details
    ISSN: 1434-453X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020203
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  • 5
    Electronic Resource
    Electronic Resource
    Biological activity of enantiomerically pure forms of insect juvenile hormone I and III inBombyx mori (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 220-221 
    Details
    ISSN: 1420-9071
    Keywords: Juvenile hormone ; enantiomer ; biological activity ; Bombyx mori ; allatectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Biological activity of enantiomerically pure juvenile hormones was assayed by topical application on allatectomizedBombyx fourth instar larvae. JHs tested were (10R)-JH I [methyl (2E,6E,10R,11S)-10,11-epoxy-3,11-dimethyl-7-ethyl-2,6-tridecadienoate], (10S)-JH I [methyl (2E, 6E, 10S, 11R)-10,11-epoxy-3,11-dimethyl-7-ethyl-2,6-tridecadienoate], (10R)-JH III [methyl (2E,6E,10R)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate] and (10S)-JH III [methyl (2E,6E,10S)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate]. Among these compounds, natural (10R)-JH I was most active and the dose needed to induce 50% larval molting was 0.04 μg/larva; it was approximately 12,000 times more active than unnatural (10S)-JH I. Though natural (10R)-JH III showed slight biological activity, it was only one three-thousandth of that of (10R)-JH I. Unnatural (10S)-JH III exhibited no biological activity at the levels assayed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02027321
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  • 6
    Electronic Resource
    Electronic Resource
    Prothoracic gland synthesis of 3-dehydroecdysone and its hemolymph 3β-reductase mediated conversion to ecdysone in representative insects (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 716-721 
    Details
    ISSN: 1420-9071
    Keywords: Molting hormone ; 3-dehydroecdysone ; 3-oxoecdysteroid 3β-reductase ; ecdysteroid ; prothoracic glands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The prothoracic glands of a variety of insects were tested for their ability to synthesize ecdysteroids in vitro. More specifically, they were evaluated for their ability to produce 3-dehydroecdysone and ecdysone using both radioimmunoassay and reverse phase high performance liquid chromatography. Three categories of insect prothoracic glands were noted: a) those producing much more 3-dehydroecdysone than ecdysone; b) glands synthesizing almost equivalent amounts of each of these two ecdysteroids; c) prothoracic glands that yielded more ecdysone than 3-dehydroecdysone. In addition, the 3-oxoecdysteroid 3β-reductase activity of the hemolymph of these insects was evaluated for its ability to convert 3-dehydroecdysone to ecdysone. The lepidopteran species tested yielded the most potent enzyme activity, although activity was demonstrated in members of other orders. These data indicate that the dehydroecdysone-ecdysone axis is not restricted to moths and butterflies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01939944
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  • 7
    Electronic Resource
    Electronic Resource
    Downhill walking: A stressful task for the anterior cruciate ligament? (1994)
    Springer
    Knee surgery, sports traumatology, arthroscopy 2 (1994), S. 2-7 
    Details
    ISSN: 1433-7347
    Keywords: Anterior cruciate ligament ; Downhill walking ; Gait analysis ; Electromyography ; Rehabilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Sports Science
    Notes: Abstract Accelerated rehabilitation after anterior cruciate ligament (ACL) reconstruction has become increasingly popular. Methods employed include immediate extension of the knee and immediate full weight bearing despite the risks presented by a graft pull-out fixation strength of 200–500 N. The purpose of this study was to calculate the tibiofemoral shear forces and the dynamic stabilising factors at the knee joint for the reasonably demanding task of downhill walking, in order to determine whether or not this task presented a postoperative risk to the patient. Kinematic and kinetic data were collected on six male and six female healthy subjects during downhill walking on a ramp with a 19% gradient. Planer net joint moments and mechanical power at the knee joint were calculated for the sagittal view using a force platform and videographic records together with standard inverse dynamics procedures. A two-dimensional knee joint model was then utilised to calculate the tibiofemoral shear and compressive forces, based on the predictions of joint reaction force and net moment at the knee. Linear envelopes of the electromyographic (EMG) activity recorded from the rectus femoris, gastrocnemius and biceps femoris muscles were also obtained. The maximum tibiofemoral shear force occurred at 20% of stance phase and was, on average, 1.2 times body weight (BW) for male subjects and 1.7 times BW for female subjects. The tibiofemoral compressive force was 7 times BW for males and 8.5 times BW for females during downhill walking. The hamstring muscle showed almost continuous activity throughout the whole of the stance phase. The gastrocnemius muscle had its main activity at heelstrike, with a second brust during the late stance phase. Knee joint shear force predictions of approximately 1000 N for a 70-kg subject greatly exceed the strength of a typical ACL graft fixation and muscular stabilisation of the knee is therefore vital to joint integrity. The hamstring muscle shows almost continuous activity during the stance phase and thereby affords some stability, but the gastrocnemius is also seen to be an important stabiliser of the knee joint in the presence of increased shear forces during early stance. Associated stability to the knee joint is indicated by compressive loadings of 7–8 times BW across the tibiofemoral joint. Whereas under normal circumstances there is sufficient dynamic joint stabilisation during downhill walking, the muscular impairment often arising postoperatively from disturbed proprioception could endanger an ACL graft. Therefore downhill walking should be avoided during the postoperative phase in order to protect the reconstruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01552646
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  • 8
    Electronic Resource
    Electronic Resource
    Phylogenetic relationships amongHomo sapiens and related species based on restriction site variations in rDNA spacers (1994)
    Springer
    Biochemical genetics 32 (1994), S. 257-269 
    Details
    ISSN: 1573-4927
    Keywords: ribosomal DNA ; restriction types ; phylogenetic relationship ; primates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A rapid method, using 12 restriction enzymes, was employed to analyze variations in ribosomal DNA (rDNA) spacers in a study of phylogenetic relationships betweenHomo sapiens and related species. We mapped restriction sites in “the external and internal spacer regions and compared the arrangements of sites. The estimated sequence divergence betweenHomo sapiens andPan troglodytes, Pan paniscus, Gorilla gorilla, Pongo pygmaeus, Hylobates lar, H. agilis, andMacaca fuscata was 2.7, 2.3, 3.8, 7.3, 6.8, 7.8, and 14.1%, respectively. The genetic relationships inferred from these distances generally correspond to those inferred from analyses of other molecular markers in the literature. The divergence betweenH. lar andH. agilis and betweenH. lar andH. syndactylus was 0.34 and 2.4%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00555829
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