Microwave Absorption and Magnetic Properties of Cobalt Ferrites/Carbon Nanotubes Nanocomposites

B. B. Zhang,P. F. Wang,J. C. Xu,Y. B. Han,H. X. Jin,D. F. Jin,X. L. Peng,B. Hong,J. Li,J. Gong,H. L. Ge,Z. W. Zhu,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5

Owing to the unique microstructure and the excellent dielectric properties, carbon nanotubes(CNTs) were decorated with CoFe2O4 nanoparticles to synthesize the CoFe2O4/CNTs nanocomposites by the solvothermal method. The phase structure, morphology, magnetic properties and microwave absorption performance of the as-prepared CoFe2O4/CNTs were characterized and discussed by X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). All results indicated that the diameter of CoFe2O4 nanoparticles decorating on the surface of CNTs increased with the solvothermal temperature. CoFe2O4/CNTs prepared at 180℃, 200℃ and 220℃ exhibited superparamagnetism, while the other samples presented ferromagnetism at room temperature. And with the increasing solvothermal temperature, the saturation magnetization and coercivity increased up to 72 emu/g and 2000 Oe for the sample prepared at 260℃ (S-26). And the reflection loss of CoFe2O4/CNTs nanocomposites increased with the solvothermal temperature up to -15.7 dB for S-26 with the bandwidth of 2.5 GHz.

Systematic analysis of genotype‐specific drug responses in cancer

Kim, Nayoung,He, Ningning,Kim, Changsik,Zhang, Fan,Lu, Yiling,Yu, Qinghua,Stemke&#x2010,Hale, Katherine,Greshock, Joel,Wooster, Richard,Yoon, Sukjoon,Mills, Gordon B Wiley Subscription Services, Inc., A Wiley Company 2012 International journal of cancer: Journal internati Vol.131 No.10

<P><B>Abstract</B></P><P>A systematic understanding of genotype‐specific sensitivity or resistance to anticancer agents is required to provide improved patient therapy. The availability of an expansive panel of annotated cancer cell lines enables comparative surveys of associations between genotypes and compounds of various target classes. Thus, one can better predict the optimal treatment for a specific tumor. Here, we present a statistical framework, cell line enrichment analysis (CLEA), to associate the response of anticancer agents with major cancer genotypes. Multilevel omics data, including transcriptome, proteome and phosphatome data, were integrated with drug data based on the genotypic classification of cancer cell lines. The results reproduced known patterns of compound sensitivity associated with particular genotypes. In addition, this approach reveals multiple unexpected associations between compounds and mutational genotypes. The mutational genotypes led to unique protein activation and gene expression signatures, which provided a mechanistic understanding of their functional effects. Furthermore, CLEA maps revealed interconnections between TP53 mutations and other mutations in the context of drug responses. The TP53 mutational status appears to play a dominant role in determining clustering patterns of gene and protein expression profiles for major cancer genotypes. This study provides a framework for the integrative analysis of mutations, drug responses and omics data in cancers.</P>

Enhanced strength and ductility in particulate-reinforced aluminum matrix composites fabricated by flake powder metallurgy

Kai, X.Z.,Li, Z.Q.,Fan, G.L.,Guo, Q.,Xiong, D.B.,Zhang, W.L.,Su, Y.S.,Lu, W.J.,Moon, W.J.,Zhang, D. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.587 No.-

Reinforcement agglomeration always leads to severe stress concentration and porosity, which is detrimental to the deformation ability and mechanical properties of particulate-reinforced metal matrix composites. In this study, uniform distribution of 32vol%B<SUB>4</SUB>C has been achieved in B<SUB>4</SUB>C/Al composite by means of flake powder metallurgy (Flake PM), in which flake Al powder is used as the starting material. The flake Al powder exhibits higher apparent volume than spherical powders of the same mass, and thus can provide more space to accommodate the B<SUB>4</SUB>C particles. Therefore, compared with conventional PM, Flake PM can lead to more uniform distribution of B<SUB>4</SUB>C particles in the composite powder as well as in the consolidated composite. Meanwhile, the flake Al powder has a nano skin of Al<SUB>2</SUB>O<SUB>3</SUB>, which could be fractured and dispersed inside the fine matrix grains during consolidation, and were found to induce a higher normalized strain hardening rate for the composite during deformation. As a result, the Flake PM 32vol%B<SUB>4</SUB>C/Al composite exhibits an ultimate tensile strength of 305MPa and a uniform elongation of 6.6%, 63% stronger and 13% more ductile than its counterpart fabricated by conventional PM.

Spectral tomographic analysis of Bremsstrahlung X-rays generated in a laser-produced plasma

Rhee, Y.J.,Nam, S.M.,Peebles, J.,Sawada, H.,Wei, M.,Vaisseau, X.,Sasaki, T.,Giuffrida, L.,Hulin, S.,Vauzour, B.,Santos, J.J.,Batani, D.,McLean, H.S.,Patel, P.K.,Li, Y.T.,Yuan, D.W.,Zhang, K.,Zhong, J. Cambridge University Press 2016 Laser and particle beams Vol.34 No.4

<B>Abstract</B><P>A new approach is proposed to analyze Bremsstrahlung X-rays that are emitted from laser-produced plasmas (LPP) and are measured by a stack type spectrometer. This new method is based on a spectral tomographic reconstruction concept with the variational principle for optimization, without referring to the electron energy distribution of a plasma. This approach is applied to the analysis of some experimental data obtained at a few major laser facilities to demonstrate the applicability of the method. Slope temperatures of X-rays from LPP are determined with a two-temperature model, showing different spectral characteristics of X-rays depending on laser properties used in the experiments.</P>

XRD studies on phase formation and the crystallite structure of BaTiO3 synthesized by HBM: the effect of calcination temperature

X.M. Chen,Y. Zhang,W.W. Kong,X.B. Bian,J.P. Zhou,P. Liu 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4

Barium titanate (BaTiO3, or BT) powders were synthesized via a solid state reaction of BaCO3-TiO2 by combining a highenergy ball milling (HBM) technique and a calcination method. Using X-ray diffraction (XRD) methods with a Rietveld refinement, the effects of calcination temperature on the phase formation and crystallite structure of BT powders were studied. It is found that by means of HBM the synthesis temperature for obtaining BT single phase is decreased to 960 oC, which is much lower than that required by the conventional solid-state reaction process, and the crystallite structure of BT is in the (pseudo)cubic form. As the calcination temperature is increased to 980 oC, the structure of BT crystallites transforms from the (pseudo)cubic to the tetragonal form. With an increase in the calcination temperature, both the tetragonality (c/a-1) and crystallite size are increased.

PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

Zheng, W.,Shen, R. F.,Sakamoto, T.,Beardmore, A. P.,De Pasquale, M.,Wu, X. F.,Gorosabel, J.,Urata, Y.,Sugita, S.,Zhang, B.,Pozanenko, A.,Nissinen, M.,Sahu, D. K.,Im, M.,Ukwatta, T. N.,Andreev, M.,Klun IOP Publishing 2012 The Astrophysical journal Vol.751 No.2

<P>We present a comprehensive analysis of a bright, long-duration (T-90 similar to 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the gamma-ray band, with optical light curve showing correlation with gamma-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to gamma-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (similar to 1100 s), a bright (R = 14.0) optical emission hump with very steep rise (alpha similar to 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R-GRB similar to 3 x 10(13) cm), initial Lorentz factor of the outflow (Gamma(0) similar to 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.</P>

Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST

Wang M.,Liu L.,Zhao L.M.,Li M.H.,Ma W.D.,Hu H.C.,Wu Z.G.,Feng J.Q.,Yang Y.,Zhu L.,Chen M.,Zhou T.A.,Jia H.,Zhang J.,Cao L.,Zhang L.,Liang R.R.,Ding B.J.,Zhang X.J.,Shan J.F.,Liu F.K.,Ekedahl A.,Gonich 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2 . Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 C, much below the permissible value of tungsten material (~1200 C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-activemultijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5 toroidally from the 4.6 GHz LH system and is not magnetically connected

Influences of the Irradiation of Intense Pulsed Ion Beam (IPIB) on the Surface of Ni₃Al Base Alloy IC6

X. Y. Le,S. Yan,W. J. Zhao,B. H. Han,Y. G. Wang,J. M. Xue,H. T. Zhang 한국진공학회(ASCT) 2002 Journal of Korean Vacuum Science & Technology Vol.6 No.2

In this paper, we treated the Ni₃Al based alloy samples with intense pulsed ion beams (IPIB) at the beam parameters of 250KV acceleration voltage, 100 - 200 A/㎤ current density and 60 ㎱ pulse duration. We simulated the thermal-mechanical process near the surface of Ni₃Al based alloy with our STEIPIB codes. The surface morphology and the cross-section microstructures of samples were observed with SEM, the composition of the sample surface layer was determined by X-ray Energy Dispersive Spectrometry (XEDS) and the microstructure on the surface was observed by Transmission Electron Microscope (TEM). The results show that heating rate increases with the current density of IPIB and cooling rate reached highest value less than 150 A/㎤. The irradiation of IPIB induced the segregation of Mo and adequate beam parameter can improve anti-oxidation property of IC6 alloy. Some craters come from extraneous debris and liquid droplets, and some maybe due to the melting of the intersection region of interphase. Increasing the pulse number enlarges average size of craters and decreases number density of craters.

Magnetic Study of Heavily Mn-doped CuO Thin Films

L. Li,B. Lv,J. Z. Cai,W. Q. Zou,X. S. Wu,F. M. Zhang 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10

Cu0.7Mn0.3O films were deposited by Plasma Enhanced Chemical Vapor Deposition and annealed in different atmospheres. The XRD diffraction results indicate that samples annealed in air and N2 both show pure CuO phases, while the film annealed in O2 has a secondary phase CuMn2O4. The content of Mn was confirmed by Energy dispersive X-ray spectroscopy. The M-T and M-H curves show that the average magnetic moment of the films prepared in O2 is larger than those prepared in air and in N2 atmosphere. Ferromagnetic segments Mn-O-Cu-O-Mn can be used to understand the ferromagnetism of CuO under heavily Mn-doping. And the magnetic moment per Mn ions calculated on the base of this chain model is consistent with the experimental result.

Feasibility of Atmospheric-Pressure CO Cold Plasma for Reduction of Supported Metal Ions

Di, L.,Zhang, X.,Lee, B.,Lu, P.,Ahn, W. S.,Park, D. W. Springer Science + Business Media 2017 Plasma chemistry and plasma processing Vol.37 No.6

<P>An atmospheric pressure (AP) carbon monoxide (CO) cold plasma method was developed and employed to reduce supported metal ions for the first time. HAuCl4, AgNO3, H2PtCl6, and Pd(NO3)(2) ions supported on a commercial sample of TiO2 (Degussa P25) were reduced by AP CO cold plasma. The results of UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and X-ray photoelectron spectroscopy (XPS) indicate that the supported metal ions are reduced to their metallic states. Au/P25-CP and Au/P25-HP were prepared by CO and H-2 cold plasma, respectively, to investigate the reduction ability of CO cold plasma. XPS and transmission electron spectroscopy analyses show that the gold nanoparticles in Au/P25-CP and Au/P25-HP exist in the form of metallic gold, and exhibit similar size. Interestingly, a blue shift of the surface plasmon resonance peak was observed for Au/P25-CP because of the amorphous carbon formed by CO dissociation. In situ optical emission spectrum of the CO cold plasma was recorded and excited CO molecules were deemed to be the reducing agents. CO cold plasma was also adopted to reduce P25 supported copper ions, while metallic copper nanoparticles were obtained accompanied by a certain amount of oxidized copper species. AP CO cold plasma is as effective as H-2 plasma for reducing supported metal ions, and has great potential for tuning the SPR absorption.</P>