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  • 2000-2004  (165)
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  • 11
    Electronic Resource
    Electronic Resource
    Magnetic properties of R(Fe1−xCox)11.3Nb0.7 (R=Y,Ho) compounds (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5293-5295 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic properties R(Fe1−xCox)11.3Nb0.7 compounds have been investigated. All of the compounds crystallize in the tetragonal ThMn12 structure. The unit cell volume slightly decreases with increasing Co content for both systems. Curie temperature (TC) almost increases linearly with increasing Co content for both systems. The maximum of saturation magnetization (Ms) appears around x=0.2 in Ho(Fe1−xCox)11.3Nb0.7 and x=0.15 in Y(Fe1−xCox)11.3Nb0.7 compounds at 5 K. The easy magnetization directions of all compounds are along the crystallographic c axis at room temperature. Thermomagnetic analysis shows that there exists no spin reorientation in the whole ordering temperature range. The magnetocrystalline anisotropy field Ba of Y(Fe1−xCox)11.3Nb0.7 exhibits a maximum with x=0.10 at 5 K and x=0.05 at room temperature, while Ba of Ho(Fe1−xCox)11.3Nb0.7 decreases monotonically with the increasing Co content at room temperature. First-order magnetization process (FOMP) has been observed in Ho(Fe1−xCox)11.3 compounds at low temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373325
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  • 12
    Electronic Resource
    Electronic Resource
    Residual stress, microstructure, and structure of tungsten thin films deposited by magnetron sputtering (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 177-187 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The residual stress and structural properties of tungsten thin films prepared by magnetron sputtering as a function of sputtering-gas pressure are reported. The films were analyzed in situ by a cantilever beam technique, and ex situ by x-ray diffraction, cross-sectional transmission electron microscopy (TEM), x-ray photoelectron spectroscopy, electron energy-loss spectrometry, and energy-filtered electron diffraction. It is found that the residual stress, microstructure, and surface morphology are clearly correlated. The film stresses, determined in real time during the film formation, depend strongly on the argon pressure and change from highly compressive to highly tensile in a relatively narrow pressure range of 12–26 mTorr. For pressures exceeding ∼60 mTorr, the stress in the film is nearly zero. It is also found that the nonequilibrium A15 W structure is responsible for the observed tensile stress, whereas the stable bcc W or a mixture of bcc W and A15 W are in compression. Cross-sectional TEM evidence indicates that the compressively stressed films contain a dense microstructure without any columns, while the films having tensile stress have a very columnar microstructure. High sputtering-gas pressure conditions yield dendritic-like film growth, resulting in complete relaxation of the residual tensile stresses. Structural details of the A15 W and amorphous W phases were also investigated at the atomic level using energy-filtered electron diffraction with reduced radial distribution function G(r) analysis. By comparing the experimental and simulated G(r) distributions, the A15 W structure is determined to be composed of ordered and stacking faulted W3W structures and the amorphous W has a disordered structure of W3O. The effect of oxygen in stabilizing the A15 phase found is explained on the basis of structural and thermodynamic stability. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371841
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  • 13
    Electronic Resource
    Electronic Resource
    Structural and magnetic properties of R(Fe1−yCoy)12−xNbx compounds (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2165-2171 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic properties of RFe12−xNbx and R(Fe1−yCoy)11.3Nb0.7 compounds with R=Y, Tb, and Dy have been investigated in the concentration region defined by 0.6〈x〈0.8 and y≤0.3, where the compounds are single phase with the ThMn12-type of structure. The Curie temperature TC of the RFe12−xNbx compounds is almost independent of the Nb content whereas the saturation magnetization Ms decreases with increasing Nb content. The spin-reorientation temperature Tsr of the TbFe12−xNbx and DyFe12−xNbx compounds decreases monotonically with increasing x. Substitution of Co for Fe in RFe11.3Nb0.7 leads to a remarkable increase of TC and the appearance of a maximum in the Co-concentration dependence of Ms. In contrast, Tsr decreases monotonically with increasing Co content for both R=Tb and Dy. The modification of T- and R-sublattice anisotropy originating from a change of the Nb content and from substitution of Co for Fe was analyzed by combining crystalline electric field theory and the individual-site model. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1425441
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  • 14
    Electronic Resource
    Electronic Resource
    Orientations of phenyl sidegroups and liquid crystal molecules on a rubbed polystyrene surface (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 784-786 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surface–specific sum–frequency vibrational spectroscopy and second-harmonic generation have been used to study the structure of a rubbed polystyrene (PS) surface and the orientation of 4′-n-pentyl-4-cyanobiphenyl (5CB) liquid crystal molecules on it. The results show that the phenyl sidegroups are well aligned by rubbing in the direction perpendicular to rubbing but tilt from the surface normal with a broad distribution. Although the PS surface is nonpolar, the 5CB molecules appear to adsorb on PS preferentially with the terminal cyano group facing the PS surface. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1435069
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  • 15
    Electronic Resource
    Electronic Resource
    High-power AlGaInN flip-chip light-emitting diodes (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3379-3381 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on high-power AlGaInN flip-chip light-emitting diodes (FCLEDs). The FCLED is "flipped-over" or inverted compared to conventional AlGaInN light-emitting diodes (LEDs), and light is extracted through the transparent sapphire substrate. This avoids light absorption from the semitransparent metal contact in conventional epitaxial-up designs. The power FCLED has a large emitting area (∼0.70 mm2) and an optimized contacting scheme allowing high current (200–1000 mA, J∼30–143 A/cm2) operation with low forward voltages (∼2.8 V at 200 mA), and therefore higher power conversion ("wall-plug") efficiencies. The improved extraction efficiency of the FCLED provides 1.6 times more light compared to top-emitting power LEDs and ten times more light than conventional small-area (∼0.07 mm2) LEDs. FCLEDs in the blue wavelength regime (∼435 nm peak) exhibit ∼21% external quantum efficiency and ∼20% wall-plug efficiency at 200 mA and with record light output powers of 400 mW at 1.0 A. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1374499
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  • 16
    Electronic Resource
    Electronic Resource
    Asymmetry diffraction magneto-optical phenomenon of NiFe grating (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2034-2036 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the asymmetry of longitudinal magneto-optical Kerr loops obtained from diffracted spots of a NiFe grating. The analysis of several series of diffracted Kerr hysteresis loops reveals that the unsaturated magnetic structure not only contributes to the shape change of Kerr loops, but also results in asymmetric feature of Kerr loops because of the nonzero value of second-order magnetic response. A suitable pattern dimension, which defines the form factor, is helpful to observe asymmetry Kerr loops. Our experiment indicates that out-of-incidence-plane diffraction may offer an alternative method to observe lateral edge domain movements in patterns. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1404126
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  • 17
    Electronic Resource
    Electronic Resource
    STUDIES OF POLYMER SURFACES BY SUM FREQUENCY GENERATION VIBRATIONAL SPECTROSCOPY (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 53 (2002), S. 437-465 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Recently, sum frequency generation (SFG) vibrational spectroscopy has been developed into a powerful technique to study surfaces of polymer materials. This review summarizes the significant achievements in understanding surface molecular chemical structures of polymer materials obtained by SFG. It reviews in situ detection at the molecular level of surface structures of some common polymers in air, surface segregation of small end groups, polymer surface restructuring in water, and step-wise changed polymer blend surfaces. Studies of surface glass transition and surface structures modified by rubbing, plasma deposition, UV light irradiation, oxygen ion and radical irradiation, and wet etching are also discussed. SFG probing of polymer surfaces provides valuable insights into the relations between polymer surface structures and surface properties, which will assist in the design of polymer materials with desired surface properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.physchem.53.091801.115126
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  • 18
    Electronic Resource
    Electronic Resource
    Jasmonic acid is involved in the water-stress-induced betaine accumulation in pear leaves (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Jasmonic acid (JA) is known to be involved in the response of plants to environmental stresses such as drought, and betaine (glycinebetaine) is an osmopretectant accumulated in plants under environmental stresses including drought. However, it remains currently unclear whether JA is involved in the water-stress-induced betaine accumulation in plant leaves. The present experiment, performed with the whole pear plant (Pyrus bretschneideri Redh. cv. Suli), revealed that the exogenously applied JA induced a significant increase of the betaine level in the pear leaves when the plants were not yet stressed by drought, and when the plants were subjected to water stress, the ‘JA plus drought’ treatment induced a significant higher betaine level than did the drought treatment alone. Meanwhile, the ‘JA plus drought’ treatment induced higher levels of betaine aldehyde dehydrogenase (BADH, E C 1.2.1.8) and activities in the leaves than did the drought treatment alone. These results obtained in the whole plant experiments were supported by the results of detached leaf experiments. In detached leaves JA induced significant increases in betaine levels, BADH activities and BADH protein amounts in a time- and concentration-dependent manner. These data demonstrate that JA is involved in the drought-induced betaine accumulation in pear leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01167.x
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  • 19
    Electronic Resource
    Electronic Resource
    Mode I crack in a soft ferromagnetic material (2002)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 25 (2002), 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: In the existing magnetoelastic theories, stress is proportional to the square of magnetic intensity and the linear model developed is usually used to analyse magnetoelastic problems. For a crack problem, the perturbation of the magnetic field caused by deformation is not much less than the applied field. In this paper, complex potentials for a mode I crack with a nonlinear relation for magnetic intensity are developed. The boundary conditions on crack faces are represented in terms of the continuity of the magnetic field. A solution of the crack problem is obtained by solving the Riemann-Hilbert problem. Making use of the solution, the effects of the boundary conditions on the crack faces on the magnetoelastic coupling are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.2002.00511.x
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  • 20
    Electronic Resource
    Electronic Resource
    Species richness of Protozoa in Japanese lakes (2000)
    Springer
    Limnology 1 (2000), S. 91-106 
    Details
    ISSN: 1439-863X
    Keywords: Key words Diversity index ; Species richness ; Lakes ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The protozoan fauna and species richness in the pelagic zone of 15 Japanese lakes were investigated in 1996 using polyurethane foam (PF) substrates. The most common species were flagellates, such as Cryptomonas erosa, Oikomonas termo, and Pleuromonas jaculans. Cinetochilum margaritaceum and Actinophrys sol were the most common species of the Ciliata and Sarcodina, respectively. The similarity of species occurrence was calculated from presence/absence data, but this revealed no clear trend with respect to the influence of lake properties such as trophic state, surface area, or mean depth. The occurrence pattern of Protozoa was most similar in L. Chuzenji and L. Biwa (north basin), two oligomesotrophic natural lakes. Log species richness was positively correlated with log total phosphorus (r = 0.54, P 〈 0.05) and negatively with log mean depth (r = −0.58, P 〈 0.05). The diversity index (Margalef's formula), highly correlated with the total species number (r = 0.85, P 〈 0.01), was negatively correlated with log lake area (r = −0.71, P 〈 0.01). The logarithm of Phytomastigophora number was positively correlated with log total nitrogen (r = 0.53, P 〈 0.05), and the logarithm of Ciliata number was negatively correlated with log lake area (r = −0.55, P 〈 0.05). The species richness of Protozoa on PF substrates was determined by both the nutrient status of the lake and the distance from the location of the suspended PF substrate to the lake bottom or shore.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s102010070015
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