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  • 1
    Electronic Resource
    Electronic Resource
    Fracture of metal-polymer line structures. I. Semiflexible polyimide (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5136-5142 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The fracture characteristics of metal/polymer line structures formed by depositing Au/Cr lines on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline (PMDA-ODA), substrate have been investigated using a stretch deformation technique. The delamination behavior, fracture morphology, fracture energy, and energy dissipation rate have been determined as a function of line width and thickness. The metal dimension was found to influence the crack formation mode and morphology. The experimental studies were supplemented by finite-element analysis to evaluate the stress distribution and deformation energetics of the line structure, which takes into account the plastic deformation of the metal and the polymer. Results from this analysis show that the observed fracture characteristics can be attributed to the edge and thickness effects induced by metal confinement. Essentially, the deformation behavior is determined by the mechanical environment induced by metal confinement at the interface. Plastic deformation of both metal and polymer plays an important role in controlling the stress distributions as well as the deformation energetics. The fracture energy of the metal-polyimide interface determined by an overall energy balance method was consistent with that obtained from energy dissipation rate. The average value is 25 J/m2 for the Au/Cr/PMDA-ODA line structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357227
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  • 2
    Electronic Resource
    Electronic Resource
    Grain boundary diffusion and its effects on the magnetic properties of Co/Cu and Co/Cr thin film bilayers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5052-5060 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray photoelectron spectroscopy has been used to investigate grain boundary diffusion of Cu and Cr through 1000-A(ring)-thick Co films in the temperature range of 300–400 °C. Grain boundary diffusivities were determined by modeling the accumulation of Cu or Cr on Co surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Cu through Co has a diffusion coefficient D0,gb of 2×104 cm2/s and an activation energy Ea,gb of 2.4 eV. Similarly, Cr grain boundary diffusion through Co thin films exhibits a D0,gb of 6×10−2 cm2/s and an Ea,gb of 1.8 eV. The Co film microstructure has been investigated before and after annealing by x-ray diffraction and transmission electron microscopy. Extensive grain growth and texturing of the magnetic film occurred during annealing for Co deposited on a Cu underlayer which is believed to influence the grain boundary diffusion process. In contrast, the microstructure of Co deposited on a Cr underlayer remained relatively unchanged upon annealing. The difference in grain growth between the two bilayers has been suggested to account for the large disparity in activation energies. Magnetometer measurements have shown that increased in-plane coercivity Hc, reduced remanence squareness S, and reduced coercive squareness S* result from grain boundary diffusion of Cu and Cr into the Co films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355747
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  • 3
    Electronic Resource
    Electronic Resource
    Characteristics of thermal stresses in Al(Cu) fine lines. I. Unpassivated line structures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 945-952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The stress evolution of unpassivated Al(Cu) fine lines under thermal cycling has been investigated as a function of linewidth using a bending beam technique. The results show that the stresses parallel (σ(parallel)) and perpendicular (σ⊥) to the line direction are lower than those measured for thin films as a consequence of stress reduction at the line edges. The edge effect is particularly effective in reducing σ⊥, although σ(parallel) is also affected. With decreasing linewidth, the effect became more pronounced, leading to an increasingly unequal biaxial stress state and a reduction in line deformation. The observed linewidth dependence can be satisfactorily accounted for by analytic or finite element calculations of the average line stresses as a function of the line aspect ratio. Results of this study validates the use of the bending beam technique for measuring the average stresses in fine line structures. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360288
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  • 4
    Electronic Resource
    Electronic Resource
    Characteristics of thermal stresses in Al(Cu) fine lines. II. Passivated line structures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 953-961 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of oxide confinement on the thermal stress and yield behavior of passivated Al(Cu) line structures have been studied as a function of linewidth to submicron dimensions using a bending-beam technique. Principal stresses in the passivated line structures were deduced based on a micromechanical analysis of the curvatures of periodic line structures with lines oriented parallel and perpendicular to the beam direction. Results from the passivated Al(Cu) lines show that with decreasing linewidth, the magnitude of the principal stress components become higher until the line aspect ratio approaching one, then decreased. This behavior is consistent with theoretical predictions by analytical methods and finite element analyses. The stress behavior of the oxide passivation has also been deduced and its magnitude depended on the oxide morphology at the sidewall of the lines. Our result indicates a high level of stress in the sidewall which may cause crack formation during thermal cycling. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360289
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  • 5
    Electronic Resource
    Electronic Resource
    Fracture of metal-polymer line structures. II. Rigid-rodlike polyimide (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5143-5148 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The fracture behavior of the Au/Cr line structures formed on a rigid-rodlike polyimide, biphenylenetetracarboxylic dianhydride-phenylenediamine (BPDA-PDA), film substrate has been investigated using a stretch deformation technique and compared with that of the Au/Cr line structures formed on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline. In general, the effects of metal line dimensions on the deformation behavior can be attributed to the changes in the mechanical environment induced by metal confinement at the line interface. This gives rise to a fracture behavior and geometrical dependence of these two polyimide structures which are qualitatively similar in most aspects. However, the fracture energy and crack propagation rate of these two polyimide line structures are quantitatively different, with values about twice higher for the BPDA-PDA line structures. This cannot be accounted for solely by the different chemical bonding; instead, the high fracture toughness of the BPDA-PDA structure has to be attributed to its superior mechanical properties, particularly its plastic deformation characteristics, which are related to its molecular structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357228
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  • 6
    Electronic Resource
    Electronic Resource
    Schwangerschaftsprotein 1 (SP1) in serum and cerebrospinal fluid of patients with gestational trophoblastic disease (1983)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 90 (1983), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The β subunit of human chorionic gonadotrophin (β-hCG) and Schwangerschaftsprotein 1 (SP1) were measured by radioimmunoassay in the serum and cerebrospinal fluid (CSF) of 46 postmolar and postpartum patients who developed gestational trophoblastic disease. There was a significant correlation between β-hCG and SP1 serum levels. The mean serum SP1 level in high-risk patients was significantly higher than that in low-risk patients. There was a significant correlation between serum and CSF β-hCG levels. The ratio of serum to CSF β-hCG levels was low in the three patients with clinical evidence of intracranial metastasis. SP1 was present in the CSF of only one of these three patients, but it could be detected in the CSF of another four patients without clinical evidence of metastases in the central nervous system. The two low-risk patients with SP1 present in the CSF showed poor response to intramuscular methotrexate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1983.tb08916.x
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  • 7
    Electronic Resource
    Electronic Resource
    Intra-operative blood loss during elective lower segment caesarean section (1992)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 99 (1992), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated wtih measured blood loss.Design Prospective observational study. Blood loss was measured in patients who underwent lower segment caesarean section in the course of routine hospital activity.Setting Tsan Yuk Hospital (Hong Kong), which is affiliated to the University of Hong Kong, 1990–1991.Subjects Forty women (mean age 29 years) with singleton pregnancies (mean gestation 38 weeks) delivered by elective lower segment caesarean section under general anaesthesia (mean birthweight 3177 g).Main outcome measure Intra-operative blood loss measured by the alkaline haematin method (intra-assay co-efficient of Variation 2.2%).Results The mean measured blood loss was 487 ml (SE 40, range 164–1438). The mean estimated blood loss was 425 ml (SE 31) range 100–1300; mode 400). Observer error in estimating blood loss was higher if measured blood loss 〉600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level 〈10.0g/dl.Conclusion Blood loss at elective lower segment caesarean section was usually 〈500 ml and was estimated with reasonable accuracy. However, there was a tendency to under-estimate blood loss when the measured loss exceeded 600 ml.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1992.tb13749.x
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  • 8
    Electronic Resource
    Electronic Resource
    Factor VIII related antigen in gestational gestational trophoblastic disease (1985)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 92 (1985), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Serum factor VIII related antigen (factor VIII R:Ag) levels were determined in 34 patients with hydatidiform mole at diagnosis and at 2, 4 and 6 weeks after evacuation of uterus and in 272 normal pregnant women. Serum factor VIII R:Ag levels in molar pregnancies before evacuation of the uterus were significantly higher than those in normal pregnancies of the same gestation age. Serum factor VIII R:Ag levels in the group of patients with residual trophoblastic disease were significantly higher than those in the group without residual tropho-blastic disease before evacuation and at 6 weeks after evacuation of uterus, but there is considerable overlap in the levels of factor VIII R:Ag between the two groups of patients especially before evacuation of uterus. Factor VIII R:Ag level does not appear to be an useful marker in predicting the outcome of hydatidiforin mole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1985.tb03001.x
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  • 9
    Electronic Resource
    Electronic Resource
    Structure and thermodynamics of nonalternating C.cntdot.G base pairs in Z-DNA: The 1.3-.ANG. crystal structure of the asymmetric hexanucleotide d(m5CGGGm5CG).cntdot.d(m5CGCCm5CG) (1993)
    s.l. : American Chemical Society
    Biochemistry 32 (1993), S. 13381-13392 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00212a002
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  • 10
    Electronic Resource
    Electronic Resource
    Adhesion and deformation of metal/polyimide layered structures (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1911-1917 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adhesion and interfacial failure of Cr, Cu, and Cu/Cr films on a thin pyromellitic dianhydride-oxydianiline polyimide substrate have been investigated using a recently developed stretch deformation technique. This method directly measures the energy required to separate the interface from the difference in the load versus elongation curves between film/substrate and substrate structures. The failure mode was observed in combination with morphological studies by in situ optical microscopy and scanning and transmission electron microscopies. The stress distribution in the sample upon stretching has been computed by a finite element analysis. The difference in the stress relief modes, film fracture, and delamination behavior for Cu versus Cr films is discussed. The important role of crack formation in the metal overlayer for initiating failure is demonstrated. The effects due to the addition of a brittle Cr interface layer between polyimide and Cu on the buildup of stress and the onset of failure have also been investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342903
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