S.Y. Chen

National Tsing Hua University, Hsin-chu-hsien, Taiwan, Taiwan

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Publications (35)74.51 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Cardiac rehabilitation (CR) after heart transplantation is known to benefit physical capacity in adults, but the advantages of CR on pediatric patients with heart retransplantation remain undetermined. Aim. The purpose of the present study was to report the effect of structured CR for a boy receiving heart transplantations twice. Design. Single case study. Setting. Inpatient and outpatient rehabilitation department Population: A pediatric patient underwent heart transplantation due to dilated cardiomyopathy at 13.6 year-old and retransplantation owing to severe cardiac allograft vasculopathy at 16.2 year-old. Methods: CR was arranged after both transplantations. Bicycle or treadmill exercises were conducted three times weekly with the intensity adjusted to the ventilatory threshold. Serial cardiopulmonary exercise tests were performed to evaluate the sequential cardiorespiratory function changes using the peak oxygen uptake ( ·VO2peak) as the primary outcome. Results: The patient had undergone 10 times of exercise tests during rehabilitation. The ·VO2peak increased from 12.27 to 15.63 mL·kg-1·min-1 within 6 months after the primary transplantation. However, the ·VO2peak dropped intensively after a rejection episode and failed to improve since the development of cardiac allograft vasculopathy. Following retransplantation, the ·VO2peak appeared worse initially but increased gradually with rehabilitation. One year subsequent to retransplantation, the ·VO2peak reached 17.7 mL·kg-1·min-1 with a 7.22 mL·kg-1·min-1 improvement compared with his baseline value. Conclusion: Structured CR improves aerobic capacity of a pediatric patient with heart retransplantation. Clinical Rehabilitation Impact. CR is safe and beneficial for pediatrics with heart retransplantation. Cardiopulmonary exercise testing can be considered as an adjuvant tool for detecting rejection or cardiac allograft vasculopathy in pediatric heart transplantation recipients.
    European journal of physical and rehabilitation medicine 03/2013;
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    ABSTRACT: Successful doping of Eu3+ ions into ZnO nanocrystals has been realized by using a low temperature wet chemical doping technique. The substitution of Eu3+ for Zn2+ is shown to be dominant in the Eu-doped ZnO nanocrystals by analyzing the X-ray diffraction patterns, transmission electron microscopy images, Raman and selectively excited photoluminescence spectra. Measurement of the luminescence from the samples shows that the excited ZnO transfers the excited energy efficiently to the doped Eu3+ ions, giving rise to efficient emission at red spectral region. The red emission quantum yield is measured to be 31% at room temperature. The temperature dependence of photoluminescence and the photoluminescence excitation spectra have also been investigated, showing strong energy coupling between the ZnO host and Eu3+ ions through free and bound excitons. The result indicates that Eu3+ ion-doped ZnO nanocrystals are promising light-conversion materials and have potential application in highly distinguishable emissive flat panel display and LED backlights.
    Journal of Nanoscience and Nanotechnology 03/2012; 12(3):2417-23. DOI:10.1166/jnn.2012.5779
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    ABSTRACT: The microstructure and magnetic properties of multilayer [Os(t)/FePt(x)]n films on a glass substrate with a 10 nm Os buffer layer by ion beam sputtering have been studied as a function of the annealing temperatures between 300 and 800 degrees C. Here, t = 0.2, 1 or 5 nm and x varied from 10, 20, 25, 50, to 100 nm with its associated n value of 10, 5, 4, 2, and 1, respectively. No diffusion evidence was found in samples with a thin Os layer and t > or = 1 nm. The average grain size of the multilayer films can be well controlled by both annealing temperature and thickness of the FePt layer by a very thin Os space layer with t > or = 1 nm. The enhancement of H(c) can be understood from the fact that for a FePt film with an Os spacer layers, the increasing number of Os layer will inhibit the grain growth of FePt grains and enriches the grain boundary. We have experimentally demonstrated that even with a very thin 1 nm Os spacer layers, the [Os(t)/FePt(x)]n multilayer films can exhibit good hard magnetic properties and are attractive candidates for ultrahigh density magnetic recording media.
    Journal of Nanoscience and Nanotechnology 12/2011; 11(12):11133-7. DOI:10.1166/jnn.2011.3997
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    ABSTRACT: We report a facile method of preparing few-layer graphene nanosheets (FLGs), which can be soluble in ethanol. Atomic force microscopy and high-resolution transmission electron microscopy studies reveal that FLGs have average thicknesses in the range of 2.6-2.8 nm, corresponding to 8-9 layers. A graphene/nafion composite film has a sheet resistance of 9.70 kΩ/sq at the transmittance of 74.5% (at 550 nm) while the nafion film on polyethylene terephthalate has a sheet resistance of 128 kΩ/sq at transmittance of 90.0%. For the cycling/bending test, almost no change in resistance was exhibited when the film was bent at an angle up to 140°, and no obvious deviation in resistance could be found after 100 bending cycles was applied. In addition, an FLGs-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite layer was demonstrated as the effective hole transporting layer to improve the hole transporting ability in an organic photovoltaic device, with which the power conversion efficiency was enhanced from 3.10% to 3.70%. The results demonstrated the promising applications of FLGs on graphene-based electronics, such as transparent electrode and flexible conducting film.
    Nanotechnology 07/2011; 22(29):295606. DOI:10.1088/0957-4484/22/29/295606
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    ABSTRACT: The microstructure, ordering parameter, and magnetic properties of multilayer [FePt(x)/Os]n films on glass substrate by dc-magnetron sputtering (with x being thickness in nm; Os with a fixed thickness 5 nm; n being the number of layers) have been studied as a function of the annealing temperatures between 300 and 900 °C. The grain size of multilayer films can be controlled by annealing temperature and thickness of the FePt layer with Os space layer. The coercivity as a function of the annealing temperature for samples with n = 1 and pure FePt behaves roughly saturated after annealing above 700 °C. However, for samples with n > 4 the value of Hc seems still increasing with increasing annealing temperature between 600 and 900 °C, and the ordering parameter decreases with increasing the number of Os layers. Our experimental results are reasonably well to describe the effect of strain-assisted transformation.
    Journal of Applied Physics 04/2011; 109. DOI:10.1063/1.3562524
  • Nanoscience and Nanotechnology Letters 04/2011; 3(2):285-288. DOI:10.1166/nnl.2011.1162
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    ABSTRACT: Strain state of ultrathin InAs-on-insulator layers obtained from an epitaxial transfer process is studied. The as-grown InAs epilayer �10–20 nm thick� on the GaSb/AlGaSb source wafer has the expected �0.62% tensile strain. The strain is found to fully release during the epitaxial transfer of the InAs layer onto a Si/SiO2 substrate. In order to engineer the strain of the transferred InAs layers, a ZrOx cap was used during the transfer process to effectively preserve the strain. The work presents an important advance toward the control of materials properties of III-V on insulator layers.
    Applied Physics Letters 01/2011; 98(1):012111. DOI:10.1063/1.3537963
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    ABSTRACT: Forming functional circuit components in future nanotechnology requires systematic studies of solid-state chemical reactions in the nanoscale. Here, we report efficient and unique methods, point and line contact reactions on Si nanowires, fabricating high quality and quantity of multiple nanoheterostructures of NiSi/Si and investigation of NiSi formation in nanoscale. By using the point contact reaction between several Ni nanodots and a Si nanowire carried out in situ in an ultrahigh vacuum transmission electron microscopy, multiple sections of single-crystal NiSi and Si with very sharp interfaces were produced in a Si nanowire. Owing to the supply limited point contact reaction, we propose that the nucleation and growth of the sugar cane-type NiSi grains start at the middle of the point contacts between two Ni nanodots and a Si nanowire. The reaction happens by the dissolution of Ni into the Si nanowire at the point contacts and by interstitial diffusion of Ni atoms within a Si nanowire. The growth of NiSi stops as the amount of Ni in the Ni nanodots is consumed. Additionally, without lithography, utilizing the line contact reaction between PS nanosphere-mediated Ni nanopatterns and a nanowire of Si, we have fabricated periodic multi-NiSi/Si/NiSi heterostructure nanonowires that may enhance the development of circuit elements in nanoscale electronic devices. Unlike the point contact reaction, silicide growth starts at the contact area in the line contact reaction; the different silicide formation modes resulting from point and line contact reactions are compared and analyzed. A mechanism on the basis of flux divergence is proposed for controlling the growth of the nano-multiheterostructures.
    Nano Letters 10/2010; 10(10):3984-9. DOI:10.1021/nl101842w
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    ABSTRACT: By making use of the dc magnetron sputtering system, the Au/FePt bilayers have been prepared on glass substrates and anodized aluminum oxide (AAO) membranes with an average pore diameter of around 200 nm. In both cases, the FePt films can be converted into the magnetically hard phase, namely L10 phase, after a heat treatment above 500 °C for 1 h. A nanoparticle-like structure can be observed in the 15-nm-thick FePt film on the AAO membrane. The experimental observations of the structure and the magnetism of the FePt films on the AAO membranes are firstly established.
    Vacuum 06/2010; 84(12):1435-1438. DOI:10.1016/j.vacuum.2010.01.046
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    ABSTRACT: The thermal stability, interlayer diffusion, and magnetic properties of FePt(100 nm) single-layer and multilayer [Os(5 nm)/FePt(25 nm)]4 films on a Si(100) substrate with/without a 10-nm-thick Os underlayer have been studied as functions of the annealing temperatures between 400 and 800 °C. The insertion of a thin Os layer into the FePt and Si(100) interface results in better thermal stability. No diffusion evidence was found in samples with an Os underlayer for annealing temperatures up to 700 °C, as seen from x-ray, transmission electron microscopy, and magnetic studies. We have experimentally demonstrated that the Os underlayer can effectively prevent the diffusion of the intermixing between the FePt layer and the Si(100) substrate for temperatures up to 700 °C. As a result of this study, the Os has potential to be a better diffusion barrier to prevent the diffusion of the FePt film on a Si(100) substrate from forming an ordered face centered tetragonal (fct) L10 hard magnetic phase.
    Journal of Applied Physics 05/2010; 107. DOI:10.1063/1.3337643
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    ABSTRACT: The high quality multiple heterostructures of Ni2Si/Si in a nanowire of Si can be formed by using the point contact reaction between several Ni nanodots and a Si nanowire carried out in-situ in an ultrahigh vacuum transmission electron microscopy. The fabricated multi-nano-heterostructures may enhance the development of circuit elements in nano-scale electronic devices. The unusual tetragonal Ni2Si (I4/mcm) phase rather than the commonly observed HCP Ni2Si (P63/m) was identified in the multiple heterostructures of Ni2Si/Si with the existence of surface oxide. The corresponding electronic structure and kinetic paths of phase transformations will be simulated and discussed.
    ECS Transactions 09/2009; 25(10).
  • 216th ECS Meeting; 01/2009
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    ABSTRACT: Recent progresses on the growth and characterization of metal silicide nanowires are highlighted. Four examples are given: 1. point contact reactions between Ni and Si nanowires and reactive epitaxial growth of axial nano NiSi/Si, 2. growth of high-density titanium silicide nanowires in a single direction on a silicon surface, 3. synthesis and characterization of metallic TaSi2 nanowires and 4. self-assembled growth of NiSi2 and α-FeSi2 nanowires by nitride mediated epitaxy.
    ECS Transactions 09/2007; 11(8). DOI:10.1149/1.2783296
  • L. J. Chen, S. Y. Chen, H. C. Chen
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    ABSTRACT: Iron disilicides have been long recognized to be one of the most interesting metal silicides since the disilicides can appear in different crystal structures and exhibit metallic, semiconducting and magnetic properties. Nanostructures have gained increasing attention for their critical roles as the building blocks of advanced devices. In this paper, recent progresses in the research on nanoscale iron disilicides are reviewed.
    Thin Solid Films 08/2007; 515(22):8140-8143. DOI:10.1016/j.tsf.2007.02.025
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    ABSTRACT: Bi-stable switching effect has been studied in nickel oxide films with three different thicknesses. The best sample of our experiments was 150-nm NiO film. Its resistance ratio between high and low states was 3.6 in endurance measurement. The maximum resistance ratio in I–V curve could reach two orders of magnitude, and it could endure over 200 times of reverse processes with the ratio remaining about 1.46. This indicates that the nickel oxide has potential to be a promising material on resistance random access memory.
    Journal of Magnetism and Magnetic Materials 03/2007; 310(2). DOI:10.1016/j.jmmm.2006.11.075
  • S.Y. Chen, Y.D. Yao, J. M. Wu
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    ABSTRACT: Effects of the Os layer on the magnetic properties of FePt/Os/FePt were investigated. The magnetic layer of FePt in the as-deposited Ta/FePt/Os/FePt/Ta thin films exhibited very strong (1 1 1) orientation in all the cases. As the thickness of Os spacer layer between 1 and 3 Å, it appeared an antiferromagnetic exchange coupling (AFC) behavior. The exchange coupling transforms to ferromagnetic when the thickness of Os spacer layer was thicker than 4 Å. Although the J value for FePt/Os/FePt thin films is −0.22 erg/cm2, which is relatively small than that of Co/Ru system, the GMR effects could be observed. In general, the AFC in multilayer system shows the first maximum of AFC peak occurring at spacer thickness between 8 and 11 Å for most spacer materials. In our investigation, this is the first time that a clear AFC behavior observed in FePt/Os/FePt system with Os spacer thickness at 2 Å.
    Journal of Magnetism and Magnetic Materials 03/2007; 310(2):1914-1916. DOI:10.1016/j.jmmm.2006.10.1105
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    ABSTRACT: MgO(0 0 1) has been growing successfully on Fe/Pd/Cu/Si(1 0 0) by e-beam evaporation as examined by X-ray diffraction and high resolution transmission microscope. We present the magnetic peculiarity of crystal structure Fe(0 0 1)/Pd(0 0 1)/Cu(0 0 1) on Si(0 0 1) substrate. The magnetic properties of the sample were measured by magneto-optical Kerr effect which shows an in-plane magnetocrystalline anisotropy.
    Journal of Magnetism and Magnetic Materials 09/2006; 304(1):e44–e46. DOI:10.1016/j.jmmm.2006.02.054
  • S.Y. Chen, Y.D. Yao, J. M. Wu
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    ABSTRACT: The CoFe/Os/CoFe thin films were deposited on natural oxidized Si(1 0 0) substrates at room temperature by an ultra-high vacuum DC-magnetron sputtering system with a base pressure less than 1×10−8 Torr. The thickness of the ferromagnetic layers was 100 Å in all cases and a series of trilayers with Os spacer ranging from 3 to 20 Å was made. Effects of the Os layer thickness on the magnetoresistance (MR) and magnetic properties were investigated. The results showed that the magnetism switched from ferromagnetic (Os thickness=3, 5 Å) to antiferromagnetic (Os thickness=7–13 Å) and then ferromagnetic (Os thickness=20 Å) again. From the MR study, we see that the AMR ratio decreased from 4.64% to the minimum value 0.69% at 9 Å and then increased; GMR ratio increased from 0.01% to the maximum value 0.43% at 9 Å and then decreased. From the hysteresis loops, the results exhibited that coercivity increased from 16 Oe to the maximum value 92 Oe at 9 Å and then decreased, and squareness value decreased from 0.97 to the minimum value 0.17 at 9 Å and then increased. Dependence of saturation field on Os spacer-layer thickness for CoFe trilayers showed a maximum value 216 Oe at 9 Å. This suggests that the small GMR effect may be related to the small exchange coupling strength in CoFe/Os/CoFe thin films.
    Journal of Magnetism and Magnetic Materials 09/2006; 304(1-304). DOI:10.1016/j.jmmm.2006.02.068
  • S.Y. Chen, L.J. Chen
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    ABSTRACT: Self-assembled epitaxial NiSi2 nanowires have been fabricated on Si(001) by reactive deposition epitaxy (RDE). The RDE method promoted nanowire growth since it provides deposited atoms sufficient kinetic energy for movement on the Si surface during the growth of silicide islands. The twin-related interface between NiSi2 and Si is directly related to the nanowire formation since it breaks the symmetry of the surface and leads to the asymmetric growth. The temperature of RDE was found to greatly influence the formation of nanowires. By RDE at 750 °C, a high density of NiSi2 nanowires was formed with an average aspect ratio of 30.
    Thin Solid Films 06/2006; 508:222-225. DOI:10.1016/j.tsf.2005.07.322
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    ABSTRACT: Endotaxial growth of self-assembled α-FeSi2 nanowires (NWs) on (100)Si has been achieved by combining reactive deposition epitaxy and nitride-mediated epitaxy. The length and the length/width aspect ratio of metallic α-FeSi2 NWs could be increased more than 12 and 6 folds to 2 μm, and 200 respectively, with a narrow width of 5–10 nm after prolonged annealing. The adjustment capability is attributed to the diminished flux of Fe adatoms mediated by the Si3N4 barrier layer to allow more complete shape transition. The scheme represents a degree of control on the morphology of self-assembled epitaxial silicide NWs not achievable otherwise.
    Applied Physics Letters 05/2006; 88(19):193114-193114-3. DOI:10.1063/1.2202701

Publication Stats

226 Citations
74.51 Total Impact Points

Institutions

  • 2003–2012
    • National Tsing Hua University
      • • Department of Materials Science and Engineering
      • • Department of Electrical Engineering
      Hsin-chu-hsien, Taiwan, Taiwan
    • National Taiwan University of Science and Technology
      • Department of Mechanical Engineering
      Taipei, Taipei, Taiwan
  • 2011
    • Academia Sinica
      • Institute of Physics
      T’ai-pei, Taipei, Taiwan
    • Fu Jen Catholic University
      T’ai-pei, Taipei, Taiwan
  • 2004–2007
    • National Chiao Tung University
      • Department of Material Science and Engineering
      Hsin-chu-hsien, Taiwan, Taiwan
  • 2002
    • Taipei Medical University
      • Department of Physical Medicine and Rehabilitation
      T’ai-pei, Taipei, Taiwan