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  • 1
    Electronic Resource
    Electronic Resource
    Lasing characteristics of low threshold ZnSe-based blue/green laser diodes grown on conductive ZnSe substrates (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 102-104 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room temperature continuous wave operation of ZnSe-based blue/green laser diodes grown homoepitaxially on conductive ZnSe substrates with threshold current densities as low as 176 A/cm2 has been demonstrated. This is the lowest reported threshold among all short wavelength lasers in the blue/green region. Lifetimes at room temperature of up to 2.1 h have been obtained for lasers with pre-existing defect densities lower than 3×104 cm−2. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121781
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  • 2
    Electronic Resource
    Electronic Resource
    Hemodynamics of small hepatocellular carcinomas (5 cm or less in diameter): Cases with discrepant findings between dynamic MR images and hepatic arteriograms (1995)
    Springer
    Abdominal imaging 20 (1995), S. 534-540 
    Details
    ISSN: 1432-0509
    Keywords: Hemodynamics ; Hepatocellular carcinoma ; Dynamic MR imaging ; Hepatic arteriography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background The degrees and patterns of contrast enhancement of small hepatocellular carcinomas (HCCs) on dynamic magnetic resonance (MR) images were compared with those on hepatic arteriograms in 61 patients. Methods Dynamic MR imaging was performed within 1 week before hepatic angiography prior to treatment, 3–4 weeks after treatment, and then once every 1–3 months if necessary. Hepatic arteriography was carried out with a coaxial microcatheter inserted into the proper hepatic artery or its distal branches. Results In 58 of 61 cases, the degrees of contrast enhancement of the tumor in dynamic MR imaging were roughly consistent with those in hepatic arteriography before treatment. In the remaining three cases, however, the tumors were depicted as hyperintense in the arterial dominant phase of the dynamic MR imaging, whereas the tumors were not detected by hepatic arteriography. The tumor detectability is 97% by dynamic MR imaging and 92% by hepatic arteriography. Furthermore, when an HCC nodule was not clearly enhanced by hepatic arteriography after treatment, it was possible by dynamic MR imaging to obtain accurate information on whether the HCC nodule had parasitic arteries. Conclusions Dynamic MR imaging was superior to hepatic angiography in contrast resolution. It was therefore considered to be useful in assessing the degrees and patterns of contrast enhancement of small HCCs before and after treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01256707
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanical properties and corrosion resistance of Ti–6Al–7Nb alloy dental castings (1998)
    Springer
    Journal of materials science 9 (1998), S. 567-574 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract With the aim of applying a novel titanium alloy, Ti–6Al–7Nb, to a dental casting material, a comprehensive research work was carried out on its characteristics, such as castability, mechanical properties and corrosion resistance in the present study. As a result, Ti–6Al–7Nb alloy exhibited sufficient castability by a dental casting method for titanium alloys and enough mechanical properties for dental application. It is also showed excellent corrosion resistance through an immersion test in 1.0% lactic acid and an anodic polarization test in 0.9% NaCl solution. From these results, it is concluded that this Ti–6Al–7Nb alloy is applicable as a dental material in place of Ti–6Al–4V alloy, which includes cytotoxic vanadium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008909408948
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of aging heat treatment on mechanical properties of biomedical Ti–Zr based ternary alloys containing niobium (1998)
    Springer
    Journal of materials science 9 (1998), S. 625-630 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Titanium–zirconium based alloys containing a small amount of niobium were investigated in order to evaluate their possible use as biomedical materials. Zirconium, which belongs to the IVa group, is known to have good corrosion resistance and biocompatibility similar to titanium. As the titanium–zirconium system shows a complete solid solution, a wide variation of alloy design is available and large quantities of solid-solution hardening must be possible. Niobium, having a β-phase stabilizing effect, was chosen as a ternary element in order to control desirably the microstructure. There have been no reports which suggest its harm to a living body. The alloys containing 2% or 3% niobium showed the highest hardness value after aging heat treatment at 773 K. In contrast to this, no alteration of hardness was seen in specimens aged at 1073 K. Through conventional X-ray diffractometry and in situ X-ray analysis using a hot stage, β-phase precipitation in the A matrix was identified. From the above results, it is concluded that alloys containing 2%–3% niobium are hopeful candidates for new kinds of biomedical alloys, when they are heat treated under suitable conditions. © 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008927407556
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  • 5
    Electronic Resource
    Electronic Resource
    Amount of hydroxyl radical on calcium-ion-implanted titanium and point of zero charge of constituent oxide of the surface-modified layer (1998)
    Springer
    Journal of materials science 9 (1998), S. 89-92 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract To compare the surface properties of calcium-ion (Ca2+)-implanted titanium with those of titanium and to investigate the mechanism of bone conductivity of Ca2+-implanted titanium, amounts of hydroxyl radical of Ca2+-implanted titanium and titanium were estimated. Also, the point of zero charge (p.z.c.) of oxide constituting surface oxides of Ca2+-implanted titanium and titanium was determined. Results showed that the amount of active hydroxyl radical on Ca2+-implanted titanium was found to be significantly larger than that on titanium, indicating that the number of electric-charging sites of Ca2+-implanted titanium in electrolyte is more than that of titanium. The p.z.c. values of rutile (TiO2), anatase (TiO2), and perovskite (CaTiO3), were estimated to be 4.6, 5.9, and 8.1, respectively. Thus, Ca2+-implanted titanium surface is charged more positively in bioliquid than titanium, accelerating the adsorption of phosphate ions. © 1998 Chapman & Hall
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008847014938
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  • 6
    Electronic Resource
    Electronic Resource
    Preferential replication-dependent mutagenesis in the lagging DNA strand inEscherichia coli (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 657-664 
    Details
    ISSN: 1617-4623
    Keywords: Asymmetrical mutagenesis ; dnaQ49 ; mutator ; Preferential lagging strand mutagenesis ; Frameshift reversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mutation frequencies attributable to −1 frameshift or one-base substitution in the structural genes coding for resistance to chloramphenicol (Cm) and tetracycline (Tc) were followed over several cycles of DNA replication, and found to differ several-fold, depending on the orientation of the gene on the plasmid with respect to the direction of (unidirectional ColE1-type) replication. The mutation frequency was higher when the reporter gene was present in the plasmid in the same orientation as the direction of the origin, i.e., when the transcription template is the lagging daughter strand, than when the gene was inserted in the opposite orientation. This significant difference in reversion frequencies of genes with different polarities was demonstrated only for a brief period of cell growth (several cycles of replication) after induction of thednaQ49 mutator, but was not observed when an increased number of replication cycles, was permitted, most probably due to fixation of the mutation into both strands. The mutated intermediate DNA which possesses a misaligned basepair in the Cm gene was demonstrated to be replicated into two progeny DNA molecules; one is the chloramphenicol-resistant (CmR) DNA synthesized from the template strand having the mutation and the other is the Cms DNA from the template strand without mutation. Our results suggest that replication-dependent mutagenesis may occur preferentially in the lagging strand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174114
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