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  • 1
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: MgO (10.4 mol%)-doped ZrO2 powder, which was prepared by coprecipitation and calcination at 750°C, was leached and milled, respectively. The powders were characterized by Auger electron scanning microprobe and XRD technologies. Only the 2.3 mol% MgO was soluble in ZrO2; it stabilized ZrO2 as the metastable tetragonal phase (crystallite size ∼45 nm) at room temperature. The rest of the MgO (8.1 mol%) existed on the surface of the ZrO2 grains in the prepared powder.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7389-7393 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of image potential due to dielectric mismatch on electronic and shallow donor impurity states in quasi-one-dimensional GaAs-Ga1−xAlxAs quantum-well wires with rectangular cross section for both finite barrier and infinitely high barrier are investigated. The results have shown that, when the image potential is included, the variations in electronic energy level and impurity binding energy are considerable, especially when the cross-section dimensions of the quantum wire become small. The results also showed that the effects of the impurity ion image potential on impurity binding energy are much larger than those of electron image potential.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    International journal of social welfare 11 (2002), S. 0 
    ISSN: 1468-2397
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Sociology
    Notes: Social work education has experienced three stages since its introduction to China in the 1920s: introduction, abolishment and reinstatement. Theoretically, there are four types of social work in China: official–educational, official–practical, voluntary–educational and voluntary–practical. In practice, all four types of social work have not necessarily been embodied in each developmental stage, and the order of their historical development is not the same as the order of their logical development; i.e. some types are lacking in some of the stages. Each type of social work has its own characteristics, which are integrated into each development stage. Today, Chinese social work faces two major interrelated tasks: the professionalisation and the institutionalisation of social work. The former refers to the development of standardisation in Chinese social work; the latter has to do with the development of the social welfare institution in general and the development of institutional welfare in particular. In general, the dramatic development in Chinese social work largely depends on the accomplishment of the two tasks.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 3192-3194 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance limits of carbon nanotube field-effect transistors (CNTFETs) are examined theoretically by extending a one-dimensional treatment used for silicon metal–oxide–semiconductor field-effect transistors (MOSFETs). Compared to ballistic MOSFETs, ballistic CNTFETs show similar I–V characteristics but the channel conductance is quantized. For low-voltage, digital applications, the CNTFET with a planar gate geometry provides an on-current that is comparable to that expected for a ballistic MOSFET. Significantly better performance, however, could be achieved with high gate capacitance structures. Because the computed performance limits greatly exceed the performance of recently reported CNTFETs, there is considerable opportunity for progress in device performance. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Contact dermatitis 51 (2004), S. 0 
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Environmental contact factors in eczema were investigated in China by clinical questionnaire and patch testing patients with a modified European standard series of allergens. 217 consecutive eczema patients were studied. Contact dermatitis (CD) was clinically diagnosed in 30% of the patients. Among the patients patch tested, 46 patients had clinically diagnosed allergic CD (ACD), 20 patients clinically had non-ACD (NACD) (including 16 cases of irritant contact dermatitis, 1 case of phototoxic contact reaction and 3 cases of asteatotic eczema) and 115 patients had clinically suspected ACD. 45 patients (98%) in the ACD group went on to have relevant patch test results. The most common ACD was from metals, fragrance materials, cosmetics and rubber materials. The most common contact allergens identified were nickel, fragrance mix, para-phenylenediamine (PPD), carba mix and thimerosal. No adverse reactions were observed to patch testing, except for pruritus in patch-test-positive patients. The positive rate of patch testing in ACD was much higher than that in NACD (98% versus 15%, P 〈 0.05, χ2-test). 60 (28%) patients had facial dermatitis (FD). Among these, 20 (33%) were confirmed as having ACD. 48 (22%) patients had hand dermatitis (HD). Among these, 7 (15%) were confirmed as having ACD. Fewer patients were confirmed as having ACD in the HD group than in the FD (15% versus 33%, P 〈 0.05, χ2-test). Although the difference was not significant, the total positivity rate in the HD group (55%) was lower than in the other groups. 65 (30%) patients had unclassified endogenous eczema (UEE). The total positive rate of patch testing in the UEE group (56%) was no different from that in the FD or HD groups. However, the relevance of positive patch tests was hard to determine in UEE. These results indicate that CD is common in eczema; relatively more patients with FD have ACD, while other factors, such as irritation, may play more of a role in HD. The total positive rate of patch testing in the UEE group was no different from that in the FD or HD groups, suggesting that patch testing should be stressed in UEE and the relevance of positive patch test results in UEE should be studied further. It is effective and safe to patch eczema patients with a modified European standard series of allergens in China.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Flexure creep and creep-recovery behavior were investigated for monolithic Al2O3 and 10-vol%-SiC-particle-reinforced Al2O3-matrix composites in an air atmosphere at temperatures of 1160°-1400°C. Two types of SiC particles were used: one has an average size of 2.7 µm and has an amount of SiO2 impurities per unit surface area that is one order of magnitude higher than the other, which has an average size of 0.6 µm. Compared to the creep behavior of monolithic Al2O3, the strain rate of the composites with the 0.6 µm SiC particles (denoted here as S-10) did not decrease; the composites with the 2.7 µm SiC particles (denoted here as L-10) exhibited excellent creep resistance. This difference was related to the microstructural features and the oxidation behavior of the composites: the Al2O3 grains in S-10 were mainly equiaxed, only ∼10% of the Al2O3 grains were elongated, and most of the SiC particles that resided at the grain boundaries or at triple-grain junctions were oxidized during creep, whereas the Al2O3 grains in L-10 were mostly irregularly shaped and elongated and most of the SiC particles were entrapped in the Al2O3 matrix grains, which prevented the oxidation of the SiC particles. These different microstructural features were associated with different amounts of SiO2 impurity content per unit surface area on the SiC particle surfaces. In addition, the monolithic Al2O3 showed no anelastic recovery when the load was removed; however, the composites exhibited significant anelastic recovery, especially for L-10. This phenomenon was attributed to the elongated grain morphology.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 654-657 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A common feature of the single-walled carbon-nanotube field-effect transistors fabricated to date has been the presence of a Schottky barrier at the nanotube–metal junctions. These energy barriers severely limit transistor conductance in the ‘ON’ state, and reduce the current ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 2575-2578 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 121-123 (Mar. 2007), p. 227-230 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 351 (Oct. 2007), p. 233-237 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The main problems for multiphase materials are the even mixing and the bonding orreacting among two or more phases, as well as the states of their grain boundaries. The mixing of twophases is usually effective by using liquid medium. The technology of second phase coating for theoriginal particles or so call nucleo-shell structure is a well approach for the even mixing. For ceramicmatrix multiphase materials low sintering temperature is the effective way to avoid the occurring ofreaction between different phases. The design of grain boundary and its stress is important for theirbonding states. The thinking for above problems would be described briefly in this paper.The purpose of multiphase materials design is expected that every phase will be playing its role,combining together and then given out a comprehensive performances. So it is necessary toconsider the following problems.1. Even mixingEven mixing between each other material is important for multiphase materials. It’s the betterwhen the processing is carrying on in the liquid state for the even mixing of two phase materials.Using physical or chemical method could be formed the fine solid particles with even dispersion oftwo or more phases materials. Usually it could be obtained nano-scale particles. The application ofnano-technology is necessary. The nano-scale mixing of two phases materials would be greatlyincreased the contacting surface of each other particles without agglomeration. Of course, if onephase of material is fine solid particle which disperses in another phase of material solution, theeven mixing of two phases is obtained similarly.Making a coating to other phase particle is a very good approach for the two phases even mixing.Coating process is attracting more and more attention in the preparation of composite materialsmainly due to its predominance in the improvement of the uniformity for different phases [1]. Thethickness of coating material determines the amount proportion of two phases which is able to becontrol. Two examples of so-called “nucleo-shell structure” will be introduced in the followingparts.Cermet composites have been widely studied due to their potential for achieving highertoughness and reasonable strength compared with ceramic matrix. But except for numbered systems,such as Co/WC and Ni/TiN, few systems have reached the people’s expectation mainly for the poorwettability between metal and ceramic. Al/Al2O3 cermet is a low density and high strength material,and it has many potential and actual applications in military, industrial and consumer regions. Toimprove the dispersive uniformity of the two phases, coating aluminum with alumina may be agood candidate since such coatings not only stabilize aluminum dispersions but also make itpossible to control inter-particle and particle-matrix interactions [2]. Figure1a-c shows the images
    Type of Medium: Electronic Resource
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