Anisotropic Magnetization and Charge Density Wave in a Na0.78CoO2 Single Crystal

이종수,J. B. Peng,S. M. Lee,C. T. Lin 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.2

Single crystals of γ-Na0.78CoO2 were grown using the floating zone method. The static magnetic susceptibility M/H(T) of Na0.78CoO2 showed significant anisotropic behavior for different crystal orientations of H ∥ (ab) and H ∥ (c). While (M/H)ab(T) for a magnetic field H= 1 T in an ab-plane followed the Curie-Weiss law at high temperatures (T ≥ 100 K), (M/H)c(T) for H ∥ c-axis deviated from Curie-Weiss behavior, which may be understood by using phonon localization from strong electron-phonon coupling. The impurity spin-1/2 effect, dressed by spin fluctuation, was significant at low temperatures (T ≤ 30 K) for both field orientations of H ∥ (ab) and H ∥ (c). The electrical resistivity ρ(T) of Na0.78CoO2 showed a clear metallic character down to 16 K, with a weak increase in the resistivity ρ(T) at low temperatures T ≤ 16 K). The gap-like behavior of ρ(T) was insensitive to applied magnetic fields up to 7 T, which indicates a non-degenerate charge gap. The electrical conductivity σ(T) followed the density wave behavior with a small energy gap (0.64 meV) at low temperatures. We discussed the electrical resistivity ρ(T)$ and the anisotropic M/H(T) behavior of Na0.78CoO2 in terms of the charge density wave and a strong electron-phonon interaction. Single crystals of γ-Na0.78CoO2 were grown using the floating zone method. The static magnetic susceptibility M/H(T) of Na0.78CoO2 showed significant anisotropic behavior for different crystal orientations of H ∥ (ab) and H ∥ (c). While (M/H)ab(T) for a magnetic field H= 1 T in an ab-plane followed the Curie-Weiss law at high temperatures (T ≥ 100 K), (M/H)c(T) for H ∥ c-axis deviated from Curie-Weiss behavior, which may be understood by using phonon localization from strong electron-phonon coupling. The impurity spin-1/2 effect, dressed by spin fluctuation, was significant at low temperatures (T ≤ 30 K) for both field orientations of H ∥ (ab) and H ∥ (c). The electrical resistivity ρ(T) of Na0.78CoO2 showed a clear metallic character down to 16 K, with a weak increase in the resistivity ρ(T) at low temperatures T ≤ 16 K). The gap-like behavior of ρ(T) was insensitive to applied magnetic fields up to 7 T, which indicates a non-degenerate charge gap. The electrical conductivity σ(T) followed the density wave behavior with a small energy gap (0.64 meV) at low temperatures. We discussed the electrical resistivity ρ(T)$ and the anisotropic M/H(T) behavior of Na0.78CoO2 in terms of the charge density wave and a strong electron-phonon interaction.

Transit-oriented development in an urban rail transportation corridor

Peng, Y.T.,Li, Z.C.,Choi, K. Pergamon Press ; Elsevier Science Ltd 2017 Transportation research Part B, Methodological Vol.103 No.-

<P>Transit-oriented development (TOD) has been recognized as an important avenue for creating a green transportation system. This paper addresses TOD investment issue in terms of the location, number and size of the TOD zones along a rail line. An urban system equilibrium problem with TOD investment is first formulated. Two social welfare maximization models, which take into account different investment regimes for TOD projects (i.e., public and private), are then proposed for optimizing TOD investment schemes along a rail line and train service frequency on that line. In the public regime model, the government is responsible for the investment cost of TOD projects, which is borne by the private property developers in the private regime model. The proposed models explicitly consider the interactions among the government, property developers and households in the urban system, together with the effects of the TOD investment on households' residential location choices and housing market. The population thresholds for investing in a TOD project under the public and private regimes are also identified. The findings show that the TOD investment can cause population agglomeration at the TOD zones and a compact city; households and the society can benefit from the TOD investment; and the private TOD investment regime outperforms the public regime in terms of total social welfare of urban system. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Measurement ofD0−D¯0mixing and search for indirectCPviolation usingD0→KS0π+π−decays

Peng, T.,Zhang, Z. P.,Abdesselam, A.,Adachi, I.,Aihara, H.,Arinstein, K.,Asner, D. M.,Aulchenko, V.,Aushev, T.,Ayad, R.,Bakich, A. M.,Bala, A.,Bhardwaj, V.,Bhuyan, B.,Bobrov, A.,Bondar, A.,Bonvicini, American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.9

We report a measurement of D-0-(D) over bar(0) mixing parameters and a search for indirect CP violation through a time-dependent amplitude analysis of D-0 -> K-S(0)pi(+)pi(-) decays. The results are based on 921 fb(-1) of data accumulated with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Assuming CP conservation, we measure the mixing parameters x = (0.56 +/- 0.19(-0.09-0.09)(+0.03+0.06))% and y = (0.30 +/- 0.15(-0.05-0.06)(+0.04+0.03))%, where the errors are statistical, experimental systematic, and systematic due to the amplitude model, respectively. With CP violation allowed, the parameters vertical bar q/p vertical bar = 0.90(-0.15-0.04-0.05)(+0.16+0.05+0.06) and arg(q/p) = (- 6 +/- 11 +/- 3(-4)(+3))degrees are found to be consistent with conservation of CP symmetry in mixing and in the interference between mixing and decay, respectively.

Deposition of ZnO thin films on GaN substrates

T. Peng,Q. M. Fu,C. Liu 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.-

ZnO thin films were deposited by electron-beam evaporation on undoped GaN and p-GaN substrates, which were grown by radio-frequency assisted molecular-beam epitaxy. It has been found that rotation of the substrate during deposition has a crucial effect on the morphology and microstructure that can be varied from nanorod growth to two-dimensional ZnO thin film growth when the substrate is changed from stationary to rotatory. Under optimized growth conditions, the morphologies of ZnO thin films are similar to those of GaN substrates. ZnO thin films were deposited by electron-beam evaporation on undoped GaN and p-GaN substrates, which were grown by radio-frequency assisted molecular-beam epitaxy. It has been found that rotation of the substrate during deposition has a crucial effect on the morphology and microstructure that can be varied from nanorod growth to two-dimensional ZnO thin film growth when the substrate is changed from stationary to rotatory. Under optimized growth conditions, the morphologies of ZnO thin films are similar to those of GaN substrates.

Computational Screening of Nanoporous Materials for Hexane and Heptane Isomer Separation

Chung, Yongchul G.,Bai, Peng,Haranczyk, Maciej,Leperi, Karson T.,Li, Peng,Zhang, Hongda,Wang, Timothy C.,Duerinck, Tim,You, Fengqi,Hupp, Joseph T.,Farha, Omar K.,Siepmann, J. Ilja,Snurr, Randall Q. American Chemical Society 2017 Chemistry of materials Vol.29 No.15

<P>Computational high-throughput screening was carried out to assess a large number of-experimentally reported metal-organic frameworks (MOFs) and zeolites for their utility in hexane isomer separation. Through the work, we identified many MOFs and zeolites with high selectivity (SL+M > 10) for the group of n-hexane, 2-methylpentane, and 3-methylpentane (linear and monobranched isomers) versus 2,2-dimethylbutane and 2,3-dimethylbutane (dibranched isomers). This group of selective sorbents includes VICDOC (Fe-2(BDP)(3)), a MOF with triangular pores that is known to exhibit high isomer selectivity and capacity. For three of these structures, the adsorption isotherms for a 10-component mixture of hexane and heptane isomers were calculated. Subsequent simulations of column breakthrough curves showed that the DEYVUA MOF exhibits a longer process cycle time than VICDOC MOF or MRE zeolite, which are previously reported, high-performing materials, illustrating the importance of capacity in designing MOFs for practical applications. Among the identified candidates, we synthesized and characterized a MOF in a new copper form with high predicted adsorbent capacity (q(L+M) > 1.2 mol/L) and moderately high selectivity (SL+M approximate to 10). Finally, we examined the role of pore shape in hexane isomer separations, especially of triangular-shaped pores. We show through the potential energy surface and three-dimensional siting analyses that linear alkanes do not populate the corners of narrow triangular channels and that structures with nontriangular pores can efficiently separate hexane isomers. Detailed thermodynamic analysis illustrates how differences in the free energy of adsorption contribute to shape selective separation in nanoporous materials.</P>

Enhancing dendritic cell vaccine potency by combining a <i>BAK/BAX</i> siRNA‐mediated antiapoptotic strategy to prolong dendritic cell life with an intracellular strategy to target antigen to lysosomal compartments

Kang, Tae Heung,Lee, Jin Hyup,Noh, Kyung Hee,Han, Hee Dong,Shin, Byung Cheol,Choi, Eun Young,Peng, Shiwen,Hung, Chien‐,Fu,Wu, T.‐,C.,Kim, Tae Woo Alan R. Liss, Inc 2007 International journal of cancer Vol.120 No.8

<P><B>Abstract</B></P><P>Dendritic cell (DC)‐based vaccines have become important in immunotherapeutics as a measure for generating antitumor immune responses. We have previously demonstrated that linkage of the antigen gene to a lysosomal targeting signal, a sorting signal of the lysosome‐associated membrane protein type 1 (LAMP‐1), enhances the potency of DC‐based vaccines. DCs have a limited life span, hindering their long‐term ability to prime antigen‐specific T cells. In this study, we attempted to further improve the potency of a DC vaccine that targets human papilloma virus 16 (HPV16) E7 to a lysosomal compartment (DC‐Sig/E7/LAMP‐1) by combining a strategy to prolong DC life. We show that small interfering RNA‐targeting Bak and Bax proteins can be used to allow transfected DCs to resist being killed by T cells. This is done by downregulating these proapoptotic proteins, which have been known as so‐called gate keepers in mitochondria‐mediated apoptosis. DCs expressing intact E7 or Sig/E7/LAMP‐1 became resistant to attack by CD8<SUP>+</SUP> T cells after transfection with <I>BAK/BAX</I> siRNA, leading to enhanced E7‐specific T cell activation <I>in vitro</I> and <I>in vivo</I>. More importantly, vaccination with E7‐presenting DCs transfected with <I>BAK/BAX</I> siRNA generated a strong therapeutic effect against an E7‐expressing tumor in vaccinated mice, compared with DCs transfected with control siRNA. Our data indicate that a combination of strategies to enhance intracellular Ag processing and to prolong DC life may offer a promising strategy for improving DC vaccine potency. © 2007 Wiley‐Liss, Inc.</P>

Solvent free synthesis of coumarin derivative by the use of AlSBA-1 molecular sieves

Peng, M.M.,Hemalatha, P.,Ganesh, M.,Palanichamy, M.,Jang, H.T. Korean Society of Industrial and Engineering Chemi 2014 Journal of industrial and engineering chemistry Vol.20 No.3

AlSBA-1 molecular sieves were synthesized successfully and used for the synthesis of coumarins through Pechmann condensation. The synthesized AlSBA-1 catalysts were characterized by XRD, BET, SEM, FTIR, TGA techniques. The synthesized materials possess large surface area with mesopores. Pechmann condensation of 3-methoxyphenol and ethyl acetoacetate was carried out under solvent free condition and 7-methoxy-4-methylcoumarin was the main product. The selectivity of the product was found to be 74.04%. Among the synthesized catalysts, AlSBA-1(2) showed high activity than others due to high density of acid sites. Hence, AlSBA-1 molecular sieves a better choice of catalyst for the synthesis of coumarins.

Anti-adherence of Antibacterial Peptides and Oligosaccharides and Promotion of Growth and Disease Resistance in Tilapia

Peng, K.S.,She, R.P.,Yang, Y.R.,Zhou, X.M.,Liu, W.,Wu, J.,Bao, H.H.,Liu, T.L. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.4

Four hundred and fifty tilapias ($6.77{\pm}0.23$ g) were assigned randomly to six groups to evaluate the feasibility of the tested antibacterial peptides (ABPs) and oligosaccharides as substitutes for antibiotics. The control group was fed with a commercial tilapia diet; other five groups were fed with the same commercial diet supplemented with konjac glucomannan (KGLM), cluster bean galactomannan (CBGAM), and three animal intestinal ABPs derived from chicken, pig and rabbit at 100 mg/kg respectively. After 21 days of feeding, growth, disease resistance, and in vivo anti-adherence were determined. Furthermore, the inhibitory effect of tested agents on adhesion of Aeromonas veronii biovar sobria (A.vbs) strain BJCP-5 to tilapia enteric epithelia in vitro was assessed by cell-ELISA system. As a result, the tested agents supplemented at 100 mg/kg show significant benefit to tilapia growth and disease resistance (p<0.05), and the benefit may be correlated with their interfering in the contact of bacteria with host mucosal surface. Although none of the tested agents did inhibit the growth of BJCP-5 in tryptic soy broth at $100{\mu}g/ml$, all of them did inhibit the adhesion of A.vbs to tilapia enteric epithelia in vivo and in vitro. In vitro mimic assays show that three ABPs at low concentrations of $25{\mu}g/ml$ and $2.5{\mu}g/ml$ have the reciprocal dose-dependent anti-adherence effect. The inhibition of ABPs may be correlated with a cation bridging and/or receptor-ligand binding, but not with hydrophobicity. The KGLM and CBGAM inhibited the adherence of BJCP-5 to tilapia enteric epithelia with dose-dependent manner in vitro, and this may be through altering bacterial hydrophobicity and interfering with receptor-ligand binding. Our results indicate that the anti-adherence of the tested ABPs and oligosaccharides may be one of the mechanisms in promoting tilapia growth and resistance to A.vbs.

Adaptive video-on-demand broadcasting in ubiquitous computing environment

Peng, Chao,Tan, Yasuo,Xiong, Naixue,Yang, Laurence T.,Park, Jong Hyuk,Kim, Soon-Seok Springer-Verlag 2009 PERSONAL AND UBIQUITOUS COMPUTING Vol.13 No.7

A split spectrum processing of noise-contaminated wave signals for damage identification

X.T. Miao,F.C. Li,Lin Ye,X.W. Sun,H.K. Peng,Ye Lu,Guang Meng 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.3

A split spectrum processing (SSP) method is proposed to accurately determine the time-of-flight (ToF) of damage-scattered waves by comparing the instantaneous amplitude variation degree (IAVD) of a wave signal captured from a damage case with that from the benchmark. The fundamental symmetrical (S0) mode in aluminum plates without and with a notch is assessed. The efficiency of the proposed SSP method and Hilbert transform in determining the ToF of damage-scattered S0 mode is evaluated for damage identification when the wave signals are severely contaminated by noise. Broadband noise can overwhelm damage-scattered wave signals in the time domain, and the Hilbert transform is only competent for determining the ToF of damage-scattered S0 mode in a noise-free condition. However, the calibrated IAVD of the captured wave signal is minimally affected by noise, and the proposed SSP method is capable of determining the ToF of damage-scattered S0 mode accurately even though the captured wave signal is severely contaminated by broadband noise, leading to the successful identification of damage (within an error on the order of the damage size) using a triangulation algorithm.