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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic properties of TM–Co–Fe–Ti spinel oxides (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5742-5742 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spin glass-like behavior has been recently observed in a ceramic Zn0.5Co0.9Fe1.2Ti0.4O4 spinel oxide.1 This motivated our interest to study how the spin glass-like behavior of magnetic clusters in a diamagnetic matrix correlates to that of nonmagnetic or weakly magnetic clusters in a ferromagnetic matrix, Mössbauer effect, ac susceptibility, field cooled and zero field cooled magnetization, hysteresis loops, and γ–γ perturbed angular correlation (PAC) have been measured for TM0.5−xCo0.9Fe1.2+xTi0.4O4 (x=0.0 and 0.2) spinel oxide with TM=Zn and Cu. The variation of coercive field with temperature has been found to fit a double exponential function form Hc(T)=H1e−β1T+H2e−β2T where Hi and βi are constants for the sample with x=0.0 and TM=Zn. The exponential increase in coercive field can be linked to increased effective clusters arising from ions occupying A and B sites with Fe on both sites. This is in agreement with the Mössbauer measurements which show superparamagnetic fluctuations. The ac susceptibility and Mössbauer spectra for Zn0.5Co0.9Fe1.2Ti0.4O4 show a glass transition temperature (about 320 K). Room temperature PAC measurements on Hf doped samples with TM=Zn showed different interaction frequencies, consistent with magnetic order in the Fe enriched case. Different behavior is observed in the sample with Cu for which the ordering temperature is about 480 K. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364710
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of high vacancy concentrations on the magnetic properties of La1−xMn1−yO3 (0.02≤x, y≤0.13) (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 394-399 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been found that the synthesis conditions and subsequent annealing treatments can significantly change the magnetic and transport behavior of the colossal magnetoresistive materials of the general formula La1−zAzMnO3, where A is a divalent ion. In order to clarify the role of vacancies within this structure, resistivity and magnetization measurements have been carried out on a series of samples derived from the parent compound LaMnO3, with La and Mn vacancies introduced by systematically varying the oxygen annealing conditions. Previous studies have shown that for a given carrier concentration, the Curie temperature of the paramagnetic to ferromagnetic transition (Tc) increases as the tolerance factor of the perovskite structure increases and then begins to decrease slowly for even higher tolerance factors. Generally, Tc also increases with the Mn4+ content, consistent with a double exchange mechanism responsible for ferromagnetism. In this study Tc was found to decrease as the vacancy concentration (and therefore the Mn4+ concentration) and tolerance factor both increase. The magnetic and transport data are discussed in the light of structural information obtained from neutron diffraction studies. In the present study it is found that La and Mn vacancies play a significant role in determining the physical properties of these materials: for high vacancy concentrations (x,y≥0.080) the magnetic properties are analogous to those of spin glasses associated with disorder and frustration. Semiconductorlike resistivity was observed for all samples at all temperatures. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366653
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray diffraction reciprocal space mapping of a GaAs surface grating (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1623-1625 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A GaAs surface grating (period 574 nm) is analyzed by four crystal-six reflection x-ray diffraction. Two-dimensional measurements in the vicinity of the 004 GaAs reciprocal lattice point show satellites in the transverse direction related to the periodicity of the grating. A cross pattern, centered on the 004 GaAs reciprocal lattice point, is formed by these satellites. An explanation is given by a model which includes the influence of transmission through the surface pattern on the substrate diffraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108606
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  • 4
    Electronic Resource
    Electronic Resource
    Reentrant metal–insulator-type transition induced by high fluence chromium ion implantation of La0.7Ca0.3MnO3 thin films (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1005-1007 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of colossal magnetoresistance (MR) material La0.7Ca0.3MnO3 were implanted with 200 keV Cr ions over a range of fluence from 1×1013 to 5×1015 ions/cm2. Resistance measurements were made in zero and applied magnetic fields of up to 8 T. At fluences of 1×1014 and 5×1014 Cr+/cm2, the resistance was much greater than in the unimplanted material and the metal–insulator transition temperature was suppressed to values below 20 K. For the highest fluence (5×1015 ions/cm2), a reentrant metal–insulator-type transition was observed and the resistance dropped significantly. Furthermore, improvement in the low-field MR was observed between the virgin and high fluence implanted films for fields less than 500 mT. These results are interpreted in terms of changes in magnetic properties with depth, defect creation, and the influence of oxygen deficiency. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122067
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  • 5
    Electronic Resource
    Electronic Resource
    Nanocrystallites in tetrahedral amorphous carbon films (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 491-493 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure of filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films is studied as a function of ion energy. An optimum energy window in the density and C–C sp3 content at an ion energy of ∼90 eV observed in this study. It is shown that the density of the amorphous carbon films are closely related to the sp3 content. The observation of nanocrystals embedded in the amorphous carbon matrix is reported. Most of the crystals observed by transmission electron microscopy can be indexed to graphite, but some of the crystals can be indexed to cubic diamond. The chemical composition of the crystals is analyzed using electron energy loss spectroscopy (EELS). The only discernible EELS edge is that of C at an energy of 285 eV. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117763
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  • 6
    Electronic Resource
    Electronic Resource
    Silanols and Cyclosiloxanes from Difunctional Cyanoalkylchlorosilanes (1961)
    s.l. : American Chemical Society
    The @journal of organic chemistry 26 (1961), S. 2008-2012 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo01065a080
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  • 7
    Electronic Resource
    Electronic Resource
    Muscle development in cultured blackspot seabream Pagellus bogaraveo: preliminary histochemical and immunohistochemical data on the fibre types (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 65 (2004), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We studied muscle ontogeny and fibre type characteristics in the blackspot seabream, a new species for commercial aquaculture. Myosin ATPase and SDH histochemistry and immunohistochemistry were tested at different ontogenetic stages, using a panel of antibodies to myosin isoforms and parvalbumin. In general, deep white muscle was parvalbumin-positive, and superficial ‘red’ muscle was parvalbumin-negative at all ages examined. At 6 days of age (transition from endogenous to exogenous feeding) three layers of muscle fibres were observed with different antimyosin reactivities: superficial monolayer, presumptive slow red (present only as a small group of fibres adjacent to the lateral line nerve), and presumptive fast-white (forming the bulk of the muscle). The superficial monolayer and presumptive slow fibres were positive for SDH. At 60 days of age (transition from live to artificial feeding) an additional fibre type was identified: a typical ‘pink’ or intermediate layer. In juveniles, the axial muscle consisted mainly of fast white fibres covered by a slow-red layer and between them a pink layer. Surprisingly, the red layer could be resolved into two distinct types by myosin immunostaining. Red fibres were also present along the horizontal septum, near the notochord. Both red and white muscle layers showed a mosaic appearance, which was confirmed by ATPase reaction. The work was financed by British Council, CRUP, and FCT (PhD Grant SFRH-BD-14068–2003).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2004.559at.x
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of dietary protein level on growth performance and body composition of juvenile blackspot seabream, Pagellus bogaraveo(Brunnich, 1768) (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 65 (2004), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Blackspot seabream Pagellus bogaraveo is a potential candidate species for southern European aquaculture. A 12-week feeding trial was then conducted to evaluate the effect of dietary protein level on growth performance, body composition and feed use efficiency of blackspot seabream juveniles (22·7 g each). Five isolipidic diets (12·5%) with graded levels of protein (20, 30, 40, 50 and 60%) were hand-distributed, twice a day, to duplicate groups of fish (120 fish per tank), until satiation. Growth (DGC), survival and feed utilization (FCR) were recorded through monthly sampling. Growth performance was significantly affected by dietary protein level (P 〈 0·05), and fish fed at the 50% protein level exhibited the highest final body mass. Feed conversion ratio decreased with increasing levels of dietary protein, fish fed 60% protein being the most efficient. No significant differences were found in whole body composition among treatments (P 〉 0·05). Financed by FCT (Project POCTI/CVT/39239/2001, PhD Grant SFRH-BD-14068–2003)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2004.559au.x
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  • 9
    Electronic Resource
    Electronic Resource
    Partial replacement of fish oil by soybean oil on lipid distribution and liver histology in European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) juveniles (2005)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture nutrition 11 (2005), S. 0 
    Details
    ISSN: 1365-2095
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A 12-week feeding trial was conducted to evaluate the effects of fish oil replacement by soybean oil, on lipid distribution and liver histology of two commercially important finfish species: rainbow trout (Oncorhynchus mykiss) and European sea bass (Dicentrarchus labrax). Sea bass (16.2 ± 0.5 g; mean ± SD) and rainbow trout (52.1 ± 0.5 g) juveniles were fed one of three isonitrogenous (500 g kg−1 CP) and isoenergetic (19 kJ g−1) diets, containing 0% (control, diet A), 25% (diet B) and 50% (diet C) soybean oil. At the end of the experiment, lipid deposition was evaluated in muscle, liver and viscera. Cholesterol and triglycerides levels were also determined in plasma. Tissue total, neutral and polar lipid composition (g kg−1 total lipids) showed no significant differences within species, regardless the dietary treatment. The same trend was observed for plasma parameters (P 〉 0.05). Viscera were the preferential tissue of lipid deposition, with 252–276 and 469–513 g kg−1 total lipid content in trout and sea bass, respectively. Dietary fish oil replacement had no effect on either hepatic lipid droplets accumulation or degree and pattern of vacuolization in the observed liver sections. These data suggest that both sea bass and trout can be fed diets containing up to 50% soybean oil without adverse effects on tissue lipid composition or liver histology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2095.2004.00337.x
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  • 10
    Electronic Resource
    Electronic Resource
    Freeze-etch localization of concanavalin A receptors to the membrane intercalated particles of human erythrocyte ghost membranes
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 363 (1974), S. 311-319 
    Details
    ISSN: 0005-2736
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2736(74)90071-6
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