Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles: DFG German National Licenses  (12)
  • Electronic Resource  (12)
  • 1990-1994  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Two spin-freezing behavior in concentrated amorphous ferrite oxides : 35th annual conference on magnetism and magnetic materials San Diego, California (USA) 29 Oct − 1 Nov 1990 (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5072-5074 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous CoFe2O4 with metal ions coordinated in a manner similar to the spinal crystal was prepared by the ion-beam sputter deposition method. The study of magnetic properties was carried out by dc- and ac-susceptibility measurements and Mössbauer spectroscopy. The strong spin-freezing behavior was observed in 80-Hz, 1-Oe ac susceptibility at two spin-freezing temperatures: 284 K (Tf1), which is considered to be caused by a random anisotropy of Co ions coordinated in distorted octahedral sites, and 86 K (Tf2), which might be caused by the frustration of antiferromagnetic interactions due to the amorphous structure. The dc susceptibility showed irreversibility below Tf1 which decreased with increasing applied field. However, a distinct change was not observed at Tf2. The Mössbauer spectrum revealed that some of the paramagnetic Fe ions were frozen below Tf1, with relaxation phenomena, and that the residual paramagnetic ions were frozen at Tf2. The time decay of the thermoremanent magnetization observed below Tf1 showed different behavior compared to that above and below Tf2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348126
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Magnetic and magnetoresistance properties in Ni80Fe20/Cu multilayers with in-plane uniaxial magnetic anisotropy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4096-4101 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic properties and magnetoresistance were investigated for Ni80Fe20/Cu multilayers with different Ni80Fe20 and Cu thicknesses that were prepared on an MgO (110) substrate using ion beam sputtering with different Ar ion acceleration voltage (VB). The structure of Ni80Fe20 is epitaxial distorted face centered tetragonal with (110) orientation, as was determined by x-ray and electron diffraction measurements. Thus, the induced in-plane uniaxial magnetic anisotropy depends on the VB and the Ni80Fe20 layer thickness. A giant magnetoresistance at room temperature was obtained up to 20% for (15 A(ring) Ni80Fe20/10 A(ring) Cu)60 multilayers, and oscillated for Cu layer thickness with 12 A(ring) period. The saturation field Hs for the giant magnetoresistance (GMR) is in good agreement with 2J/dMs, where J, d, and Ms are layer exchange coupling, magnetic layer thickness, and saturation magnetization, respectively. The small field changes ΔH of 20 and 8 Oe needed for GMR were attained for n=16 (MR=12%) and 2 (MR=6.5%), respectively, in (70 A(ring) Ni80Fe20/10 A(ring) Cu)n with in-plane uniaxial anisotropy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354455
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Influence of a large amount of Co substitution on the magnetic properties of NdFeCoGaB magnets (abstract) (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4777-4777 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have found that a NdFeCoGaB sintered magnet containing 30 at. % Co still shows high coercive force in spite of such a large amount of Co substitution. The Curie temperature of the magnet is higher than that of the ternary NdFeB magnet by 280 °C. As a result, the following magnetic properties have been attained for Nd14.5Fe46Co30Ga1B8.5: Tc=590 °C, Br =11.7 kG, Hci =14.3 kOe, and (BH)max=32 MG Oe. Furthermore, in this magnet there exists an additional phase, Nd1(FeCoGa)4B1 with Ce1Co4B1 structure, which, as far as authors know, has not been reported to exist in the NdFeB-based magnets. In this study we investigated the magnetic properties and microstructure of Nd14.5Fe76−xCoxGa1B8.5 (x=16–50) sintered magnets. The high coercive force can be obtained in the Co-content region from 16 to 30 at. %. In particular, the magnet with 30 at. % Co shows coercive force as high as 14.3 kOe. However, further substitution of Co drastically deteriorates the magnetic properties. The coercive force of the magnet with 50 at. % Co is less than 1 kOe. From the metallographical point of view, the above-mentioned Nd1(FeCoGa)4B1 phase is not observed in the magnets containing less than 30 at. % Co. This phase abruptly appears in the magnet with 30 at. % Co and its amount increases with increasing Co content. The strongest x-ray-diffraction peak observed in the magnet with 50 at. % Co comes from the Nd1(FeCoGa)4B1 phase. The demagnetization-curve measurements suggest that reverse magnetic domains are nucleated in the Nd1(FeCoGa)4B1 phase at a low reverse magnetic field. It is noteworthy that the magnet with 30 at. % Co maintains the high coercive force in spite of the existence of such a soft magnetic phase. Details will be discussed in the coming session.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344784
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Giant magnetoresistance dependence on Ar acceleration voltage in Co9Fe/Cu and Co3Fe/Cu multilayers (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2436-2438 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In relation to theoretical predictions on the importance of randomness at the interface to determine the cause for giant magnetoresistance, argon acceleration voltage (VB) in ion beam sputtering was changed for preparing a set of CoxFe1−x/Cu multilayers. We found that the magnetoresistance as quite sensitive to the argon acceleration voltage and had a maximum around VB=600 V. Perfect antiferromagnetic coupling of the CoxFe1−x layers via thin Cu layers and the oscillation behavior of this indirect exchange coupling with a 12 A(ring) period were observed for VB=600 V. These results suggest the importance of the interface state for giant magnetoresistance in multilayers. We also found that a small saturation field can be induced, which can be explained by the metamagnetic transition associating the relation of Ku(approximately-greater-than)J/tCoFe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106997
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Saturation fields in Co-Fe/Cu multilayers with giant magnetoresistance: In-plane uniaxial magnetic anisotropy effects (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 726-728 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetization processes are investigated by calculation and experiments for Co-Fe/Cu multilayers with giant magnetoresistance, which are prepared on MgO(110) substrates using ion beam sputtering and have in-plane uniaxial magnetic anisotropy (Ku). The experiments show the metamagnetic transition from antiferromagnetic spin structure to ferromagnetic one for an easy axis external field. This is supported by calculation of the magnetic phase diagram for stable magnetization configurations, which shows the metamagnetic transition to occur for (J12/d)/Ku≤1, where J12 is antiferromagnetic layer interaction and d is magnetic layer thickness. The saturation fields from antiferromagnetic to ferromagnetic spin structures are substantially decreased by induction of the in-plane uniaxial anisotropy. The relation Hsh − 2Hse = 2Ku/Ms, found for the saturation fields by the calculation, is confirmed experimentally for the multilayers, where Ms is the saturation magnetization, and Hse and Hsh are the saturation fields for the external field parallel to the easy and hard axes, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107780
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Amorphous oxides with ferromagnetic exchange coupling and optical transparency (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5796-5798 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 0.5La1−xSrxMnO3⋅0.5B2O3 (0.2≤x≤1.0) oxides were melt quenched using a twin-roll technique. The resultant ribbons were amorphous for thicknesses below 30 μm, which was confirmed by x-ray diffraction, anomalous x-ray scattering, and transmission electron microscopy. They were characterized by high crystallization temperatures above 920 K and optical transparency. Their Curie temperatures are higher than 380 K over a wide range of Sr concentrations (0.3≤x≤1.0), thus differing from crystalline La1−xSrxMnO3 perovskites. Magnetic susceptibility above the Curie temperature follows the Curie–Weiss law with a positive paramagnetic Curie temperature, suggesting ferromagnetic spin coupling in the present amorphous oxides. The ferromagnetic behavior of the amorphous state may be explained by positive double-exchange interactions of Mn3+ and Mn4+ ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345967
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Enzyme-cytochemical study of small ganglion cells in experimental thiamine deficiency: concerning the pain mechanism (1991)
    Springer
    Acta neuropathologica 81 (1991), S. 396-400 
    Details
    ISSN: 1432-0533
    Keywords: Thiamine monophosphatase ; Pyrithiamine ; Thiamine deficiency ; Small ganglion cells ; Electron microscopic cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an effort to clarify the mechanism of pain accompanying thiamine deficiency, thiamine monophosphatase (TMPase) activity was demonstrated, by means of electron microscopic cytochemistry, in small ganglion cells in pyrithiamine-treated thiamine-deficient rats. TMPase activity was seen to be present in the reticular part of the Golgi complex and vesicle-like bodies around the trans side of the Golgi complex. By the 10th day after the initial pyrithiamine treatment, a significant increase in the number of TMPase-positive vesicle-like body was observed. These results indicate that thiamine deficiency causes a disturbance in the transportation and/or production of TMPase, which is an integral part of the synaptic transmission of the nociception impulses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293460
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Biological monitoring of acrylonitrile exposure through a new analytical approach to hemoglobin and plasma protein adducts and urinary metabolites in rats and humans (1993)
    Springer
    International archives of occupational and environmental health 65 (1993), S. S103 
    Details
    ISSN: 1432-1246
    Keywords: Acrylonitrile ; Adducts ; Biological monitoring ; Gas chromatography ; Hemoglobin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new, simple and fast procedure of measuring acrylonitrile (ACN) in ACN derived mercapturic acids such as S-(2-cyanoethyl)-L-cysteine(CyEC), and in hemoglobin (Hb) and plasma protein adducts and urinary metabolites in rats and humans exposed to ACN was developed. ACN in mercapturic acids or proteins was analyzed by capillary gas chromatography (GC) by liberating ACN at a high-temperature in the injector port of GC with or without oxidizing sulfur atoms of the ACN-bound cysteines into sulfoxide form by hydrogen peroxide in vitro. At 350 °C, more than 90% of ACN in authentic CyEC was recovered by this method. Increasing a single ip dose of ACN from 5 to 50 mg/kg produced proportional increases in ACN bound to Hb 24 hr after the treatment. The alkylation of plasma protein with ACN was about 1/10 as low as that of Hb. After repeated daily ip doses of 1–10 mg/kg, ACN in Hb decreased with a half-life of about 9 days. ACN was also detected in the blood of workers exposed to ACN for 1 to 10 years at a Siberian synthetic rubber factory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381317
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Diketopiperazine-mediated peptide formation in aqueous solution (1990)
    Springer
    Origins of life and evolution of the biospheres 20 (1990), S. 249-257 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Though diketopiperazines (DKP) are formed in most experiments concerning the prebiotic peptide formation, the molecules have not been paid attention in the studies of chemical evolution. We have found that triglycine, tetraglycine or pentaglycine are formed in aqueous solution of glycine anhydride (DKP) and glycine, diglycine or triglycine, respectively. A reaction of alanine with DKP resulted in the formation of glycylglycylalanine under the same conditions. These results indicate that the formation of the peptide bonds proceeds through the nucleophilic attack of an amino group of the amino acids or the oligoglycines on the DKP accompanied by the ring-opening. The formation of glycine anhydride, di-, tri- and tetraglycine was also observed in a mixed aqueous solution of urea and glycine in an open system to allow the evaporation of ammonia. A probable pathway is proposed for prebiotic peptide formation through diketopiperazine on the primitive Earth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01808107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Prebiotic synthesis of orotic acid parallel to the biosynthetic pathway (1990)
    Springer
    Origins of life and evolution of the biospheres 20 (1990), S. 389-399 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract By heating an aqueous solution of aspartic acid and urea, carbamylaspartic acid is first formed and then the molecule is cyclized to dihydroorotic acid (DHO) with loss of water. Irradiation of an aqueous solution of DHO with a tungsten lamp yields orotic acid by photo-dehydrogenation of the molecule. This pathway of orotic acid formation is quite similar to that of biosynthesis of the molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01808133
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...