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  • 1
    ISSN: 1432-0630
    Keywords: PACS: 61.20.Ja; 62.20.Dc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: PACS: 61.16.Ch; 68.35.Bs; 82.65.My
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 60 molecules, adsorbed on Si(100)–(2×1) surfaces under ultra-high-vacuum conditions, can be obtained using scanning tunneling microscopy and spectroscopy. High-resolution images of individual C60 molecules, physisorbed (preannealed) and chemisorbed (postannealed) on different sites on the same sample, reveal clear intramolecular features superimposed on the molecules’ cage structure that are consistent with their bonding nature. Spectroscopic measurements of individual C60 molecules chemisorbed at these sites yield energy levels that exhibit a transition of their electronic structure from that of a near-free adsorbate to that of SiC. The spectroscopic data corresponds to the observed changes in local density of states. These results demonstrate the power of scanning tunneling microscopy to determine the electronic structure and bonding characteristics of individual molecules.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0630
    Keywords: PACS: 85.42.+m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0630
    Keywords: PACS: 81.15; 68.55; 77.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Ferroelectric Bi4Ti3O12 thin films with single phase and nanosized microstructure were prepared on Pt/Ti/SiO2/Si(111) substrate by metalorganic solution deposition using titanium butoxide and bismuth nitrate at relatively low annealing temperatures. The internal strain in Bi4Ti3O12 thin films was calculated from the peak shifts and broadening of XRD patterns. With increase in annealing temperature, the uniform strain decreased from positive to zero and then to negative, and the non-uniform strain decreased and was negative. The total strain was negative and in the range of -0.2%–-1.0%, from which the stress of the films was calculated to be about -1.4×109 N/m2. The mode values of strain decreased with increase in annealing temperature and increased with increase in film thickness. The dielectric constant increased with increase in annealing temperature and film thickness. The dielectric properties were interpreted by considering the influence of strain, grain size, and grain boundaries. The strain lowered the polarization and increased the dielectric constant. The larger the grain size and the thinner the grain boundary, the greater the dielectric constant. The influence of grain size and grain boundary was stronger than that of the strain.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9605
    Keywords: twin domains ; YBCO ; Co-doping ; twin boundary ; model ; electron diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The existence of twin domains in YBa2(Cu1−x Co x )3O y samples was confirmed by many experiments. However, the physical picture of the twin domains has not been reported up to now. By analyzing oxygen content, Cu and Co valences, and Co coordination in those samples, we propose a domain model, which consists of two pairs of parallel zigzag Co-O chains surrounding orthorhombic cells, one along (110) direction and the other along (110) direction. The zigzag Co-O chains are the twin walls, with neighboring walls perpendicular and the opposite ones parallel. The distance between parallel walls (i.e., zigzag Co-O chains) depends upon Co concentration of sample. The twin domain model predicts the geometry, size, and absence of systematic symmetry of the domains. The model also predicts the modulation periodicity of electron diffraction patterns, which depends on Co concentration. All the predictions by the model agree well with the experimental results reported in literatures. Furthermore, the model indicates the possible existence of two domains, which have incommensurable modulation periodicity.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1572-9605
    Keywords: Thin films ; magnetization ; pinning force ; flux creep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Magnetization measurements have been performed onc-axis oriented Y- and Gd-based superconductive films in a wide range of the temperaturesT (4.2–85 K) and magnetic fieldsH (0–8 T) withH∥ c-axis. The influence of flux creep on both the temperature dependence of critical current densityJ cm and the scaling behavior of flux pinning forceF p has been discussed in detail. The experimental results show that Y and Gd films have different pinning mechanism. Flux pinning-force peaks in high fields are observed in Gd film at high temperatures and can be considered as evidence for collective pinning.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9567
    Keywords: density ; dielectric constant ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new equation for determining the density of nonpolar substances based on measurements of dielectric constants is presented. Applying the new equation to nitrogen at a density from 1 to 30 mol·L−1, the mean deviation of the results calculated from the equation is of the order of 10−4, which is the same as the uncertainty of the experimental data. Owing to its analytical form, the derived equation can be applied to indicate the density of nonpolar substances with a densitometer, without adding error to the experimental uncertainty. This equation is also capable of determining the mean polarizabilities and molecular diameters, which agree well with results from other investigators. We suggest that the equation derived here can be applied to some other nonpolar substances as well.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9605
    Keywords: Field distribution ; type II superconductor ; cylindrical shape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The self-field effects $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B'}$$ of bulk magnetization current are considered when the applied field $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B} _a$$ is parallel to the rotation axis of a cylinder-shaped type-II superconductor with limited axial length L and radius R, and by using finite-element analysis in a self-consistent way, the field-dependent magnetization current density function $$J_m (|B|)[\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B} (\rho ,z) = \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B} _a + \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B'} (\rho ,z)]$$ , the current density, and the field distributions are derived from magnetic moment hysteresis loop m(B a) for the superconductor with full field penetration. When B a≫B p, the average field inside the cylinder $$\left\langle B \right\rangle = \mu _0 [H_a + f_c (L/2R)M]$$ in the Bean model approximation, and the function f c(L/2R) is quantitively given for arbitrary parameter L/2R, where B a=μ0 H a and M=m/(πR 2 L). In addition, the influences of the self-field on the measured m(B a) loop are discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9605
    Keywords: V-t curve ; I c measurement ; Ag-Bi2223 tapes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Based on the collective creep model, we numerically studied evolution of electric field and current density in superconductors and its influence on transport measurements of critical current. It is shown that many experimental facts, such as the dependence of V-I curves on sweeping rate of applied current and voltage relaxation are the results of this evolution. The simulation results are confirmed by electric transport measurements on Ag-sheathed Bi2−x Pb x Sr2Ca2Cu3O y tapes. Discussions on influences of the voltage relaxation on electric transport measurements including superconducting critical current are made.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2018-06-02
    Description: Objective Although the role of microRNA-17 (miR-17) has been identified as a tumour biomarker in various studies, its prognostic value in cancers remains unclear. Therefore, we performed a systematic review and meta-analysis to analyse and summarise the relationship between the miR-17 status and clinical outcome in a variety of human cancers. Design Systematic review and meta-analysis. Data sources PubMed, Web of Science and Embase from the first year of records to 15 May 2017. Outcomes The patients’ survival results were pooled, and pooled HRs with 95% CIs were calculated and used for measuring the strength of association between miR-17 and the prognosis of cancers, including hepatocellular carcinoma, lung cancer, osteosarcoma, glioma, T-cell lymphoblastic lymphoma and colon cancer. Heterogeneity, publication bias and subgroup analysis were also conducted. Results A total of 1096 patients were included in this meta-analysis from 12 articles. The results indicated that the increased expression of miR-17 played an unfavourable role in overall survival in various human carcinomas with the HR of 1.342 taking into account the publication bias. In subgroup analysis, HR of ethnicity (Caucasian HR=1.48 and Asian HR=1.40), disease (digestive system HR=1.36 and blood system cancer (HR=2.38), detection method (quantitative real-time PCR HR=1.40 and in situ hybridisation, HR=2.59) and detection sample (tissue HR=1.45 and serum HR=1.32) were significant with p〈0.05. For the analysis of disease-free survival and recurrence-free survival, the increased expression of miR-17 was associated with unfavourable prognosis (HR=1.40). Conclusions miR-17 may be a useful biomarker in predicting the clinical outcome of human cancers, but due to the limitations of the current studies, further verification of the role of miR-17 in human malignancies is urgently needed. PROSPERO registration number CRD42017065749
    Keywords: Open access, Genetics and genomics
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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