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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 2766-2769 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 1373-1376 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 50 (1994), S. 302-316 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The three-dimensional structure of human dicupric monooxalate lactoferrin, Cu2oxLf, has been determined to 2.0 Å resolution, using X-ray diffraction data collected by diffractometry to 2.5 Å resolution, and oscillation photography on a synchrotron source to 2.0 Å resolution. Difference electron-density maps calculated between Cu2oxLf and both dicupric lactoferrin, Cu2Lf, and diferric lactoferrin, Fe2Lf, showed that the oxalate had replaced a carbonate in the C-terminal binding site, and that, relative to Cu2Lf, there were no significant differences in the N-terminal site. The structure was then refined crystallographically by restrained least-squares methods. The final model, in which the r.m.s. deviation in bond distances is 0.017 Å, contains 5314 protein atoms (691 residues), two Cu2+ ions, one bicarbonate ion, one oxalate ion, 325 solvent molecules and one sugar residue. The crystallographic R factor of 0.193 is for 46 134 reflections in the range 8.0 to 2.0 Å resolution. The oxalate ion is coordinated to copper in a 1,2-bidentate fashion, and the added bulk of the anion results in the rearrangement of the side chains of nearby arginine and tyrosine residues. No other major alterations in the molecule can be observed, the overall protein structure being the same as that for Cu2Lf and Fe2Lf.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 32 (1992), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Maximum arrowleaf sida (Sida rhombifolia L.) germination occurred at 35°C, whereas prickly sida (Sida spinosa L.) germinated to the same extent at 35 or 40°C. Arrowleaf sida germinated better than prickly sida at 20 and 25°C, but did not germinate at 40°C. Less than 50% of seed from both species were viable at 45°C after 21 days of exposure. Both species exhibited more than 75% germination at a range of pH from 5.0 to 8.0. Arrowleaf sida germinated to a greater extent than prickly sida from 0 to —800 kPa, and an osmotic stress of —200 kPa reduced prickly sida germination, whereas —400 kPa was necessary to reduce arrowleaf sida germination. Prickly sida emergence was optimal at a planting depth of 0.5 cm, and declined rapidly at deeper planting depths. However, arrowleaf sida emergence was equivalent at planting depths of 0.5–2.0 cm, with declining emergence below 2.0 cm. Neither species emerged from depths exceeding 5.0 cm. Light did not influence the germination of arrowleaf sida or prickly sida.Sida rhombifolia et Sida spinosa: germination et leveeLe maximum du germination pour Sida rhombifolia L. a été atteint à 35°C tandis que Sida spinosa L. a germé de facon équivalente à 35 ou 40°C. S. rhombifolia a mieux germé que S. spinosaà 20 et 25°C, mais n'a pas germéà 40°C. Moins de 20% de graines des deux espèces étaient encore viables à 45°C après 21 jours dèxposition. Les deux especes ont germéà plus de 75% dans des niveaux de pH allant de 5 à 8. S. rhombifolia a mieux germe que S. spinosa de 0 à 800 kPa, et un stress osmotique de —200 kPa a réduit la germination de S. spinosa, tandis que —400 kPa ont été nécessaires pour réquire la germination de S. rhombifolia. La levée de S. spinosaétait optimale à une profondeur de semis de 0,5 cm, et décroissait rapidement à des profondeurs plus élevées. Cependant la levée de S. rhombifoliaétait équivalente pour des profondeurs de 0,5 à 2 cm, avec une baisse à partir de 2 cm. Aucune des deux espèces n'a levéà des profondeurs supérieurs à 5 cm. La lumière n'a pas d'influence sur la germination des 2 espèces. Keimung und Auflaufen der Sidafaserpflanze (Sida rhombifolia L.) und der Stacheligen Samtmalve (Sida spinosa L.)Die stärkste Keimung lag bei der Sidafaserpflanze (Sida rhombifolia L.) bei 35 °C vor, während Samen der Stacheligen Samtmalve (Sida spinosa L.) bei 35 oder 40 °C gleich gut keimten. Samen der Sidafaserpflanze keimten bei 20 und 25 °C besser als die der Stacheligen Samtmalve, keimten jedoch nicht bei 40 °C. Nach Lagerung bei 45 °C für 21 Tage waren die Samen beider Arten zu 〈 20% keimfähig. Bei pH-Werten zwischen 5 und 8 keimten beide Arten zu 〉75%. Bei osmotischen Drücken zwischen 0 und —800 kPa keimte die Sidafaserpflanze besser als die Stachelige Samtmalve, deren Keimung ab —200 kPa gehemmt wurde, wahrend bei der Sidafaserpflanze —400 kPa erforderlich waren, die Keimung zu verringern. Samen der Stacheligen Samtmalve keimten am besten in 0,5 cm Tiefe, in gröβerer Ablagetiefe schnell schlechter. Bei der Sidafaserpflanze jedoch waren Aussaattiefen zwischen 0,5 und 2,0 cm gleich gut, erst bei Tiefen unter 2 cm ging der Auflauf zurück. Aus Tiefen unter 5 cm keimte keine der beiden Arten. Durch Licht wurde die Keimung der beiden Sida Arten nicht beeinflußt.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Oxidation of metals 35 (1991), S. 139-173 
    ISSN: 1573-4889
    Keywords: internal oxidation ; HfO2 ; solubility product ; linear kinetics ; oxygen trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The internal oxidation of some binary Nb-Hf and several commercial Nb alloys containing Hf was studied at 1568 and 1755°C in oxygen pressures ranging from 5×10 −5 to 1×10−3 torr.The reaction kinetics were linear, suggesting that diffusion of oxygen in the substrate was not rate-controlling. The dependence of the reaction rate on oxygen pressure was linear also. Well-defined reaction fronts were observed at higher pressures and the lower temperature, whereas ill-defined fronts occurred at lower pressures and at the higher temperature. The solubility product was much higher than normally encountered in Wagnerian-type behavior and gave rise to varying solute content across the internal-reaction zone. The solute-concentration profiles (EPMA/WDS) of the matrix between particles exhibited a sigmoidal shape for well-defined reaction fronts, whereas the profiles showed a gradual decrease in solute with distance near the front for ill-defined fronts, dropping fairly abruptly at the metal/gas interface. The solute concentration never reached zero at the surface for any condition studied. In contrast to classical, Wagnerian behavior, solute continued to precipitate out after the reaction zone had passed, leading to a variation in the mole fraction of oxide in the zone. SEM/EDXA and XRD showed that precipitation occurred by the formation of “precursors” (Hf-rich regions surrounded by Hf-depleted regions), followed by precipitation of tetragonalHfO2,which in some cases transformed to monoclinicHfO2 and subsequently coarsened. The precipitate morphology varied with solute concentration, temperature, oxygen pressure, and location within the reaction zone. High temperature and high oxygen pressure favored a Widmanstätten structure, whereas low temperature and low oxygen pressure favored a spheroidal precipitate structure. Widmanstätten plates were observed to “spheroidize” at longer times, suggesting that the interfacial energy between particles and matrix was very high. The presence of a small amount of Y (0.11 w/o in C129) always resulted in spheroidal particles. It appears that Y markedly increased the particle/matrix interfacial energy. Microhardness profiles showed decreasing values with distance into the sample for some conditions and alloys but increasing values in other cases. Hardness increases in the substrate in advance of the interface showed that oxygen activity did not reach zero at the reaction front, once again contrary to classical behavior but consistent with high solubility products of the oxide. Results are analyzed in terms of oxygen-trapping by reactive solutes as noted in the literature for both lattice-parameter measurements and oxygen diffusivity studies.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localization of a plasma membrane calcium pump in the oviduct of the laying hen was investigated by immunohistochemical techniques, utilizing a monoclonal antibody (5F10) produced against the human erythrocyte calcium pump. This antibody was shown to react with an epitope of the pump in oviductal tissue, and prominent staining was observed on the microvilli of the tubular gland cells of the hen shell gland (uterus) and the isthmus. The Ca2+ pump was not detectable in the infundibulum or the magnum. Calbindin-D28k, also localized by immunohistochemical means, was observed to be present in the tubular gland cells of the shell gland and the distal isthmus (adjacent to shell gland) but not in either the proximal isthmus (adjacent to the magnum), the magnum or the infundibulum. The localization of the Ca2+ pump in the oviduct corresponds to known sites of mineral deposition during egg shell formation. The distribution of calbindin-D28k differed, co-localizing with the Ca2+ pump in the shell gland and distal isthmus but not in the proximal isthmus. This might reflect a greater rate of active Ca2+ secretion in the distal isthmus and shell gland as compared to the proximal isthmus.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 152-158 
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; Acrosome reaction ; Monoclonal antibody ; Zona-free hamster eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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