9.
First-principles studies of the hydrogenation effects in silicene sheets - Zhang, P.; Li, X. D.; Hu, C. H.; Wu, S. Q.; Zhu, Z. Z.; 朱梓忠
Using density functional theory (DFT) with both the generalized gradient approximation (GGA) and hybrid functionals, we have investigated the structural, electronic and magnetic properties of a two-dimensional hydrogenated silicon-based material. The compounds, i.e. silicene, full- and half-hydrogenated silicene, are studied and their properties are compared. Our results suggest that silicene is a gapless semimetal. The coverage and arrangement of the absorbed hydrogen atoms on silicene influence significantly the characteristics of the resulting band structures, such as the direct/indirect band gaps or metallic/semiconducting features. Moreover, it is interesting to see that half-hydrogenated silicene with chair-like structure is shown to be a...
10.
Tailoring of polar and nonpolar ZnO planes on MgO (001) substrates through molecular beam epitaxy - Zhou, Hua; Wang, Hui-Qiong; Liao, Xia-Xia; Zhang, Yufeng; Zheng, Jin-Cheng; Wang, Jia-Ou; Muhemmed, Emin; Qian, Hai-Jie; Ibrahim, Kurash; Chen, Xiaohang; 陈晓航; Zhan, Huahan; Kang, Junyong; 康俊勇
Polar and nonpolar ZnO thin films were deposited on MgO (001) substrates under different deposition parameters using oxygen plasma-assisted molecular beam epitaxy (MBE). The orientations of ZnO thin films were investigated by in situ reflection high-energy electron diffraction and ex situ X-ray diffraction (XRD). The film roughness measured by atomic force microscopy evolved as a function of substrate temperature and was correlated with the grain sizes determined by XRD. Synchrotron-based X-ray absorption spectroscopy (XAS) was performed to study the conduction band structures of the ZnO films. The fine structures of the XAS spectra, which were consistent with the results of...
11.
Statistical two-dimensional correlation spectroscopy of urine and serum from metabolomics data - Xu, Jingjing; Cai, Shuhui; Li, Xuejun; Dong, Jiyang; Ding, Jun; Chen, Zhong; 陈忠
Statistical two-dimensional correlation spectroscopy combined with pattern recognition is demonstrated for coanalysis of NMR spectroscopic data from different sources. The urine and serum H-1 NMR spectra from metabolomics datasets of diabetes and hyperthyroidism are taken as examples. The intrinsic covariance of certain molecules between urine and serum spectra is identified. The highly urine-serum-correlated metabolites are further analyzed by using the projection to latent structure discriminant analysis (PLS-DA) method. To illustrate the applicability of the method, the metabolomics datasets of diabetes and hyperthyroidism are imported separately to calculate the corresponding two-dimensional urine-serum correlation coefficient matrixes. The results show that creatinine (delta...
12.
Time-reversal symmetry breaking phase in the Hubbard model: A variational cluster approach study - Lu, Xiancong; 卢先聪; Chioncel, Liviu; Arrigoni, Enrico
We study the stability of the time-reversal symmetry breaking staggered-flux phase of a single band Hubbard model, within the variational cluster approach. For intermediate and small values of the interaction U, we find metastable solutions for the staggered-flux phase, with a maximum current per bond at U approximate to 3.2. However, allowing for antiferromagnetic and superconducting long-range order it turns out that in the region at and close to half filling the antiferromagnetic phase is the most favorable energetically. The effect of nearest-neighbor interaction is also considered. Our results show that a negative nearest-neighbor interaction and finite doping favors the...
13.
Mechanical properties of platinum nanowires: An atomistic investigation on single-crystalline and twinned structures - Wen, Yu-Hua; Huang, Rao; Zhu, Zi-Zhong; 朱梓忠; Wang, Quan
We present a systematic investigation on the mechanical properties of platinum nanowires with single-crystalline and fivefold twinned structures by means of atomistic simulations. The results show that the Young's moduli of both types of nanowires are significantly higher than that of bulk counterpart. Furthermore, the fivefold twinned nanowire generally exhibits a higher elastic modulus than the single-crystalline one. The introduction of the twinned structures enhances the yielding strength of the nanowires but remarkably lowers their ductility. The initiation of the yielding mechanism of the two types of nanowires is through a nucleation process and the activity of Shockley partial dislocations...
14.
Ti/CeOx(111) interfaces studied by XPS and STM - Zhou, Yinghui; 周颖慧; Zhou, Jing
Low coverage of Ti was deposited on the well-ordered CeOx(111) (1.5 < x < 2) thin films grown on Ru(0001) by physical vapor deposition at room temperature. The structure and interaction of Ti/ceria interfaces were investigated with X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) techniques under ultrahigh vacuum conditions. XPS data indicate that the deposition of Ti on both oxidized and reduced ceria surfaces causes the partial reduction of Ce from +4 to +3 state. Ti is formally in the +4 state. STM data show the formation of small atomic-like titania features at...
15.
Plasma Inactivation of Candida albicans by an Atmospheric Cold Plasma Brush Composed of Hollow Fibers - Song, Ying; Liu, Dongping; Ji, Longfei; Wang, Wenchun; Niu, Jinhai; Zhang, Xianhui; 张先徽
It remains a challenge to generate the uniform and large-area cold plasma at atmospheric pressure. In this paper, we report a method to generate a reliable and homogeneous brush-shaped plasma plume running at atmospheric pressure. The plasma brush (110 mm in length and 10 mm in width) is mainly composed of well-aligned and hollow optical fibers. Current-voltage measurements indicate that the brush-shaped plasma plume consists of glowlike pulsed discharge with their pulsewidths of several microseconds. The generation of the He/O-2 glowlike discharge is further proved by the uniform distribution of O atoms along the transverse location of the plasma brush....
16.
Epitaxial growth of thick Ge layers with low dislocation density on silicon substrate by UHV/CVD - Chen Cheng-Zhao; Zheng Yuan-Yu; Huang Shi-Hao; Li Cheng; Lai Hong-Kai; 赖洪凯; Chen Song-Yan; 陈松岩
Thick Ge epitaxial layers are grown on Si(001) substrates in the ultra-high vacuum chemical vapor deposition system by using the method of low temperature buffer layer combining strained layer superlattices. The microstructure and the optical properties of the Ge layers are characterized by double crystal X-ray diffraction, HRTEM, AFM and photoluminescence spectroscopy. The root-mean-square surface roughness of the Ge epilayer with a thickness of 880nm is about 0.24 nm and the full-width-at-half maximum of the Ge peak of the XRD profile is about 273 ''. The etch pit density related to threading dislocations is less than 1.5 x 10(6) cm(-2)....
17.
EtOH induced formation of nanographite fractions and their reorganization on nanostructured CeO2 films - Li, Heng; 李恒; Nie, Jia Cai; Kunsagi-Mate, Sandor
Multiwalled carbon nanotubes (MWCNTs) were etched by EtOH treating. Such treated MWCNTs were deposited from solution phase onto the nanostructured CeO2 films. High resolution images by both transmission and scanning electron microscopy showed that the nanographite fractions are existed in the solution and they were also reorganized on the surface. On the nanostructured surface of specific morphology, the nanographite fractions are deposited into the valleys between the CeO2 islands and therefore a selective pattern of nanographite was formed. Molecular dynamics calculations highlighted that adsorption and reorganization properties of the nanographite layers have considerable dependence on the morphology of CeO2 nanostructures....
18.
Detection of sulfur dioxide gas with graphene field effect transistor - Ren, Yujie; Zhu, Chaofu; Cai, Weiwei; 蔡伟伟; Li, Huifeng; Ji, Hengxing; Kholmanov, Iskandar; Wu, Yaping; Piner, Richard D.; Ruoff, Rodney S.
Graphene grown by chemical vapor deposition on a Cu foil and transferred onto a Si wafer has been used to fabricate a field effect transistor device that was used to study the sensing of SO2 gas. It was found by in-situ measurements that the SO2 strongly p-dopes the graphene and dramatically shifts its Dirac point. This effect was used to monitor the SO2 gas. The detector can be completely reset by thermal annealing at 100 degrees C in high vacuum. The response and recovery of the detector are faster at higher temperatures. Moreover, the sensitivity of the SO2 graphene detector...
19.
Pt-Pd Bimetallic Catalysts: Structural and Thermal Stabilities of Core-Shell and Alloyed Nanoparticles - Huang, Rao; Wen, Yu-Hua; Zhu, Zi-Zhong; 朱梓忠; Sun, Shi-Gang; 孙世刚
Atomic-level understanding of structural characteristics and thermal behaviors of nanocatalysts is important for their syntheses and applications. In this article, we present a systematic study on structural and thermal stabilities of Pt-Pd bimetallic nanoparticles with core shell and alloyed structures by using atomistic simulations. It was revealed that the Pd-core/Pt-shell structures are the least structurally stable, while the inverted Pt-core/Pd-shell nanoparticles are more stable than the alloyed ones when the Pt percentage exceeds 42% or so. The origin for this order was clarified through analysis of atomic energy distribution in these structures. Furthermore, the core-shell structures exhibit enhanced thermal stability...
20.
Modulation of Schottky Barrier Height of Metal/TaN/n-Ge Junctions by Varying TaN Thickness - Wu, Zheng; Huang, Wei; Li, Cheng; Lai, Hongkai; Chen, Songyan; 陈松岩
This paper demonstrates experimentally the modulation of the Schottky barrier height (SBH) of metal/TaN/n-Ge junctions by varying the TaN thickness in a dual stacked metal layer. The effective SBH for the metal/TaN/n-Ge Schottky junctions, originally pinned at 0.53-0.61 eV, decays to 0.44 eV, the barrier height of TaN/n-Ge, with an increase in the TaN thickness from 0 to 10 nm, independent of the type of metal. Dipole formation at the TaN/Ge interface is proposed to alleviate the metal-induced gap states and shift the pinning level toward the conduction band. The modulation of the SBH can be ascribed to the interdiffusion...
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