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Role of activity in human dynamics
Zhou, T.,Kiet, H. A. T.,Kim, B. J.,Wang, B.-H.,Holme, P. Editions de Physique 2008 Europhysics letters Vol.82 No.2
<P>The human society is a very complex system; still, there are several non-trivial, general features. One type of them is the presence of power-law–distributed quantities in temporal statistics. In this letter, we focus on the origin of power laws in rating of movies. We present a systematic empirical exploration of the time between two consecutive ratings of movies (the <I>interevent time</I>). At an aggregate level, we find a monotonous relation between the activity of individuals and the power law exponent of the interevent time distribution. At an individual level, we observe a heavy-tailed distribution for each user, as well as a negative correlation between the activity and the width of the distribution. We support these findings by a similar data set from mobile phone text-message communication. Our results demonstrate a significant role of the activity of individuals on the society-level patterns of human behavior. We believe this is a common character in the interest-driven human dynamics, corresponding to (but different from) the universality classes of task-driven dynamics.</P>
Zhou, W.,Yamamoto, G.,Fan, Y.,Kwon, H.,Hashida, T.,Kawasaki, A. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.106 No.-
<P>Quantitative characterization of interfacial shear strength (IFSS), in multi-walled carbon nanotube (MWCNT)-reinforced Al matrix composites, has been carried out using an in-situ pull-out technique. The end of an MWCNT protruding out of the tensile fracture surface of the composite was bonded to the tip of an atomic force microscopy (AFM) cantilever using an electron-beam-induced deposition method. The MWCNT was pulled out from the Al matrix using a nanomanipulator system installed inside a scanning electron microscope (SEM). The effective embedded length of the MWCNT incorporated in the Al matrix was evaluated by observing the pulled out MWCNT under high-resolution transmission electron microscopy (HRTEM). Valid results were obtained for six MWCNTs with straight, visibly damage-free embedded parts nearly perpendicular to the fracture surface. The IFSS between the MWCNT and the Al matrix was 24.8 +/- 3.2 MPa. The ultimate tensile strength (UTS) of the MWCNT/Al composites is in good agreement with that estimated by the shear lag model using these IFSS values, resulting in the realization of 60% load transfer efficiency at the directly contacted MWCNT-Al interface in the MWCNT/Al composites. No MWCNT failure was observed during the pullout in this study. (C) 2016 Elsevier Ltd. All rights reserved.</P>
ZhEng, D. W.,Huang, Y. P.,Tang, T. A.,Cui, Q.,Li, A. Z.,Zhou, S. X.,He, Z. J.,Chen, Z.,Zhang, X. J.,Kwor, R. 대한전자공학회 1993 ICVC : International Conference on VLSI and CAD Vol.3 No.1
A novel process for silicon on insulator(SOI) technology has been presented. Single crystal Si is grown by molecular beam epitaxy(MBF) on a porous silicon(PS) system consisting of two layers of PS with different microstructures. Subsequent lateral oxidation converts the structure to SOI wish excellent insulation property. Si islands with a width of 135㎛ and low doping concentration have been achieved.
Kim, D. J.,Ha, D.,Zhou, Q.,Thokchom, A.,Lim, J.,Lee, J.,Park, J.,Kim, T. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.27
<P>Nanowires (NWs) with a high surface-to-volume ratio are advantageous for bio- or chemical sensor applications with high sensitivity, high selectivity, rapid response, and low power consumption. However, NWs are typically fabricated by combining several nanofabrication and even microfabrication processes, resulting in drawbacks such as high fabrication cost, extensive labor, and long processing time. Here, we show a novel NW fabrication platform based on 'crack-photolithography' to produce a micro-/nanofluidic channel network. Solutions were loaded along the microchannel, while chemical synthesis was performed in the nanoslit-like nanochannels for fabricating silver nanobelts (AgNBs). In addition, the NW/NB fabrication platform not only made it possible to produce AgNBs in a repeatable, high-throughput, and low-cost manner but also allowed the simultaneous synthesis and alignment of AgNBs on a chip, eliminating the need for special micro- and/or nanofabrication equipment and dramatically reducing the processing time, labor, and cost. Finally, we demonstrated that the AgNBs can be used as chemical sensors, either as prepared or when integrated in a flexible substrate, to detect target analytes such as hydrogen peroxide.</P>
Structural Study and Optical Response of Ag:Bi2O3 Nanoswitch Materials
P. Zhou,L. Y. Chen,J. Li,T. A. Tang,Y. H. Wu,Y. R. Chen,Y. Y. Lin 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.5I
Materials are always the .rst power of our science and technology. In this paper, we explored he linear and nonlinear optical responses of silver/bismuth oxide composite thin .lms, with special mphasis on the relation between the third-order nonlinear optical susceptibility and the metal omposition and metal particle size. The intrinsic optical properties of Ag:Bi2O3 composite .lms re revealed for the .rst time by our research. The maximum value of the third-order optical usceptibility A(3) was 4:1 £ 10¡10 esu, which occurred at a 35.7 % Ag concentration.With increasing nnealing temperature, the maximum value of A(3)observed was 2.1 £ 10¡9 esu, which occurred ter heat treatment at 600 ±C. We also studied the structure and the crystallinity of the samples by sing X-ray diraction and atomic force microscope techniques before and after annealing. Based on he femtosecond nanoswitch eect we revealed, the Ag:Bi2O3 composite materials have promising otential applications in next generation communication technology.
Hydrochlorofluorocarbon and hydrofluorocarbon emissions in East Asia determined by inverse modeling
Stohl, A.,Kim, J.,Li, S.,O&,apos,Doherty, S.,Mü,hle, J.,Salameh, P. K.,Saito, T.,Vollmer, M. K.,Wan, D.,Weiss, R. F.,Yao, B.,Yokouchi, Y.,Zhou, L. X. Copernicus GmbH 2010 Atmospheric Chemistry and Physics Vol.10 No.8
<P>Abstract. The emissions of three hydrochlorofluorocarbons, HCFC-22 (CHClF2), HCFC-141b (CH3CCl2F) and HCFC-142b (CH3CClF2) and three hydrofluorocarbons, HFC-23 (CHF3), HFC-134a (CH2FCF3) and HFC-152a (CH3CHF2) from four East Asian countries and the Taiwan region for the year 2008 are determined by inverse modeling. The inverse modeling is based on in-situ measurements of these halocarbons at the Japanese stations Cape Ochi-ishi and Hateruma, the Chinese station Shangdianzi and the South Korean station Gosan. For every station and every 3 h, 20-day backward calculations were made with the Lagrangian particle dispersion model FLEXPART. The model output, the measurement data, bottom-up emission information and corresponding uncertainties were fed into an inversion algorithm to determine the regional emission fluxes. The model captures the observed variation of halocarbon mixing ratios very well for the two Japanese stations but has difficulties explaining the large observed variability at Shangdianzi, which is partly caused by small-scale transport from Beijing that is not adequately captured by the model. Based on HFC-23 measurements, the inversion algorithm could successfully identify the locations of factories known to produce HCFC-22 and emit HFC-23 as an unintentional byproduct. This lends substantial credibility to the inversion method. We report national emissions for China, North Korea, South Korea and Japan, as well as emissions for the Taiwan region. Halocarbon emissions in China are much larger than the emissions in the other countries together and contribute a substantial fraction to the global emissions. Our estimates of Chinese emissions for the year 2008 are 65.3±6.6 kt/yr for HCFC-22 (17% of global emissions extrapolated from Montzka et al., 2009), 12.1±1.6 kt/yr for HCFC-141b (22%), 7.3±0.7 kt/yr for HCFC-142b (17%), 6.2±0.7 kt/yr for HFC-23 (>50%), 12.9±1.7 kt/yr for HFC-134a (9% of global emissions estimated from Velders et al., 2009) and 3.4±0.5 kt/yr for HFC-152a (7%). </P>
Observation of the topological surface state in the nonsymmorphic topological insulator KHgSb
Liang, A. J.,Jiang, J.,Wang, M. X.,Sun, Y.,Kumar, N.,Shekhar, C.,Chen, C.,Peng, H.,Wang, C. W.,Xu, X.,Yang, H. F.,Cui, S. T.,Hong, G. H.,Xia, Y.-Y.,Mo, S.-K.,Gao, Q.,Zhou, X. J.,Yang, L. X.,Felser, C. American Physical Society 2017 Physical review. B Vol.96 No.16
<P>Topological insulators represent unusual topological quantum states, typically with gapped bulk band structure but gapless surface Dirac fermions protected by time-reversal symmetry. Recently, a distinct kind of topological insulator resulting from nonsymmorphic crystalline symmetry was proposed in the KHgX (X = As, Sb, Bi) compounds. Unlike regular topological crystalline insulators, the nonsymmorphic glide-reflection symmetry in KHgX guarantees the appearance of an exotic surface fermion with hourglass shape dispersion (where two pairs of branches switch their partners) residing on its (010) side surface, contrasting to the usual two-dimensional Dirac fermion form. Here, by using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of KHgSb on both (001) and (010) surfaces and reveal the unique in-gap surface states on the (010) surface with delicate dispersion consistent with the 'hourglass Fermion' recently proposed. Our experiment strongly supports that KHgSb is a nonsymmorphic topological crystalline insulator with hourglass fermions, which serves as an important step to the discovery of unique topological quantum materials and exotic fermions protected by nonsymmorphic crystalline symmetry.</P>
Hu, X -T,Zhang, F -B,Fan, Y -C,Shu, X -S,Wong, A H Y,Zhou, W,Shi, Q -L,Tang, H -M,Fu, L,Guan, X -Y,Rha, S Y,Tao, Q,He, C Macmillan Publishers Limited 2009 Oncogene Vol.28 No.26
Located at the important tumor suppressor locus, 3p22, PLCD1 encodes an enzyme that mediates regulatory signaling of energy metabolism, calcium homeostasis and intracellular movements. We identified PLCD1 as a downregulated gene in aerodigestive carcinomas through expression profiling and epigenetic characterization. We found that PLCD1 was expressed in all normal adult tissues but low or silenced in 84% (16/19) gastric cancer cell lines, well correlated with its CpG island (CGI) methylation status. Methylation was further detected in 62% (61/98) gastric primary tumors, but none of normal gastric mucosa tissues. PLCD1 methylation was significantly correlated with tumor high stage. Detailed methylation analysis of 37 CpG sites at the PLCD1 CGI by bisulfite genomic sequencing confirmed its methylation. PLCD1 silencing could be reversed by pharmacological demethylation with 5-aza-2′-deoxycytidine, indicating a direct epigenetic silencing. Ectopic expression of PLCD1 in silenced gastric tumor cells dramatically inhibited their clonogenicity and migration, possibly through downregulating MMP7 expression and hampering the reorganization of cytoskeleton through cofilin inactivation by phosphorylation. Thus, epigenetic inactivation of PLCD1 is common and tumor-specific in gastric cancer, and PLCD1 acts as a functional tumor suppressor involved in gastric carcinogenesis.Oncogene (2009) 28, 2466–2475; doi:10.1038/onc.2009.92; published online 18 May 2009