Activation of antiferromagnetic domain switching in exchange-coupled Fe/CoO/MgO(001) systems

Li, Q.,Chen, G.,Ma, T. P.,Zhu, J.,N'Diaye, A. T.,Sun, L.,Gu, T.,Huo, Y.,Liang, J. H.,Li, R. W.,Won, C.,Ding, H. F.,Qiu, Z. Q.,Wu, Y. Z. American Physical Society 2015 Physical review. B, Condensed matter and materials Vol.91 No.13

Effects of Dietary Energy Density on Growth, Carcass Quality and mRNA Expression of Fatty Acid Synthase and Hormone-sensitive Lipase in Finishing Pigs

Liu, Z.H.,Yang, F.Y.,Kong, L.J.,Lai, C.H.,Piao, X.S.,Gu, Y.H.,Ou, X.Q. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.10

A single factorial experiment was conducted to test the effects of three dietary levels of energy on mRNA expression of fatty acid synthase (FAS-mRNA) and hormone-sensitive lipase (HSL-mRNA) and their association with intramuscular fat in finishing pigs. 72 crossbred (Large $White{\times}Rongchang$) barrows with an average initial body weight of 20.71 (s.e. 0.1) kg, were randomly allotted to three dietary treatments (11.75, 13.05 and 14.36 MJ DE/kg) and fed until slaughtered at 100 or 101 kg. The diets were iso-nitrogenous and iso-essential amino acids. The growth performances including the duration of finishing were changed linearly (p<0.05) or quadratically (p<0.05) with increased dietary energy levels. The effects of dietary energy content on the percentage of external fat, intramuscular backfat and the fat thickness were linear (p<0.05). The content of dietary energy increased FAS-mRNA linearly or quadratically, while HSL-mRNA decreased linearly or quadratically in backfat and Longissmus dorsi muscle. Meanwhile, significant positive correlations (p<0.05) were found between energy level and intramuscular fat, FAS-mRNA or the ratio of FAS-mRNA to HSL-mRNA, between the ratio of FAS-mRNA to HSL-mRNA and intramuscular fat. However, the correlations between HSL mRNA and dietary energy or intramuscular fat were negative (p<0.05). The results indicated that dietary energy level regulates lipid accumulation, especially intramuscular fat, possibly by modulating the mRNA of FAS and HSL together rather than individually.

Long-term MAX-DOAS network observations of NO2 in Russia and Asia (MADRAS) during the period 2007–2012: instrumentation, elucidation of climatology, and comparisons with OMI satellite observations and global model simulations

Kanaya, Y.,Irie, H.,Takashima, H.,Iwabuchi, H.,Akimoto, H.,Sudo, K.,Gu, M.,Chong, J.,Kim, Y. J.,Lee, H.,Li, A.,Si, F.,Xu, J.,Xie, P.-H.,Liu, W.-Q.,Dzhola, A.,Postylyakov, O.,Ivanov, V.,Grechko, E.,Ter Copernicus GmbH 2014 Atmospheric Chemistry and Physics Vol.14 No.15

<P>Abstract. We conducted long-term network observations using standardized Multi-Axis Differential optical absorption spectroscopy (MAX-DOAS) instruments in Russia and ASia (MADRAS) from 2007 onwards and made the first synthetic data analysis. At seven locations (Cape Hedo, Fukue and Yokosuka in Japan, Hefei in China, Gwangju in Korea, and Tomsk and Zvenigorod in Russia) with different levels of pollution, we obtained 80 927 retrievals of tropospheric NO2 vertical column density (TropoNO2VCD) and aerosol optical depth (AOD). In the technique, the optimal estimation of the TropoNO2VCD and its profile was performed using aerosol information derived from O4 absorbances simultaneously observed at 460-490 nm. This large data set was used to analyze NO2 climatology systematically, including temporal variations from the seasonal to the diurnal scale. The results were compared with Ozone Monitoring Instrument (OMI) satellite observations and global model simulations. Two NO2 retrievals of OMI satellite data (NASA ver. 2.1 and Dutch OMI NO2 (DOMINO) ver. 2.0) generally showed close correlations with those derived from MAX-DOAS observations, but had low biases of up to ~50%. The bias was distinct when NO2 was abundantly present near the surface and when the AOD was high, suggesting a possibility of incomplete accounting of NO2 near the surface under relatively high aerosol conditions for the satellite observations. Except for constant biases, the satellite observations showed nearly perfect seasonal agreement with MAX-DOAS observations, suggesting that the analysis of seasonal features of the satellite data were robust. Weekend reduction in the TropoNO2VCD found at Yokosuka and Gwangju was absent at Hefei, implying that the major sources had different weekly variation patterns. While the TropoNO2VCD generally decreased during the midday hours, it increased exceptionally at urban/suburban locations (Yokosuka, Gwangju, and Hefei) during winter. A global chemical transport model, MIROC-ESM-CHEM (Model for Interdisciplinary Research on Climate-Earth System Model-Chemistry), was validated for the first time with respect to background NO2 column densities during summer at Cape Hedo and Fukue in the clean marine atmosphere. </P>

Investigation on the Unlubricated Sliding Tribological Properties of Ti–20Zr–6.5Al–4V Alloy at Elevated Temperatures

H. Zhong,L. Q. Yang,Y. Yue,C. P. Zhang,F. X. Jin,M. Gu,M. Z. Ma 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.12

In this study, unlubricated sliding friction and wear properties of a recently-developed TiZr-based alloy (Ti–20Zr–6.5Al–4V, TZ20 hereafter) were tested at elevated temperatures ranging from room temperature to 673 K. After the tribologicaltests, worn surface and cross-section of TZ20 alloy were analyzed to illustrate its wear behavior. The results showed that thewear rate was increased firstly with the ambient temperature, which then decreased when the temperature exceeded criticaltransition temperature (473 K). Also, the dominant wear mechanisms changed from adhesive wear at room temperature toabrasive wear at 473 K, and then to mild abrasive wear at highest ambient temperature of 673 K. The variations of wearbehaviors could be attributed to tribo-oxide layer formed during sliding process. At ambient temperature of 673 K, the tribooxidelayer formed on the surface was thicker and more compact, and showed more obvious protective role on tribologicalproperties of TZ20 alloy.

Use of negative capacitance to simulate the electrical characteristics in double-gate ferroelectric field-effect transistors

Y.G. Xiao,M.H. Tang,Y. Xiong,J. C. Lin,C.P. Cheng,B. Jiang,H.Q. Cai,Z.H. Tang,X.S. Lv,X.C. Gu,Y.C. Zhou 한국물리학회 2012 Current Applied Physics Vol.12 No.6

The surface potential and drain current of double-gate metal-ferroelectric-insulator-semiconductor (MFIS) field-effect transistor were investigated by using the ferroelectric negative capacitance. The derived results demonstrated that the up-converted semiconductor surface potential and low subthreshold swing S = 34 (<60 mV/dec) can be realized with appropriate thicknesses of ferroelectric thin film and insulator layer at room temperature. What’s more, a reduction gate voltage about 260 mV can be reached if the ON-state current is fixed to 600 mA/mm. It is expected that the derived results can offer useful guidelines for the application of low power dissipation in ongoing scaling of FETs.

Cytotoxicity and Cells Growth Status on Ag+-implanted Pyrolytic Carbon and TiN/Ag Multilayer Films

X. M. Cai,H. Q. Tang,T. Liu,J. Zhao,H. Q. Gu,R. Z. Cui 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.-

Ag+-implanted pyrolytic carbon and TiN/Ag multilayer films were prepared by ion implantation and ion beam assisted deposition. L-929 cells (mice fibroblast) were cultured in the extracted medium of Ag+-implanted pyrolytic carbon and TiN/Ag multilayer film samples for cytotoxicity testing. The adhesion, spreading, proliferation and morphology of human umbilical vein endothelial cells (HUVEC) on both samples were also investigated. The results show that the cytotoxicity grade of Ag+-implanted pyrolytic carbon is less than 1˚ when the implanted dose is under 1×10 16 ions/cm² and the cytotoxicity grade of TiN/Ag multilayer films with modulation period of 7.5 nm is within the range of 0 to 1˚ indicating that both samples have no cytotoxicity to L-929. HUVEC on both Ag+-implanted pyrolytic carbon and TiN/Ag multilayer film sample grows well, showing that they have good biocompatibility. Ag+-implanted pyrolytic carbon and TiN/Ag multilayer films were prepared by ion implantation and ion beam assisted deposition. L-929 cells (mice fibroblast) were cultured in the extracted medium of Ag+-implanted pyrolytic carbon and TiN/Ag multilayer film samples for cytotoxicity testing. The adhesion, spreading, proliferation and morphology of human umbilical vein endothelial cells (HUVEC) on both samples were also investigated. The results show that the cytotoxicity grade of Ag+-implanted pyrolytic carbon is less than 1˚ when the implanted dose is under 1×10 16 ions/cm² and the cytotoxicity grade of TiN/Ag multilayer films with modulation period of 7.5 nm is within the range of 0 to 1˚ indicating that both samples have no cytotoxicity to L-929. HUVEC on both Ag+-implanted pyrolytic carbon and TiN/Ag multilayer film sample grows well, showing that they have good biocompatibility.

Emergence of room-temperature ferroelectricity at reduced dimensions

Lee, D.,Lu, H.,Gu, Y.,Choi, S.-Y.,Li, S.-D.,Ryu, S.,Paudel, T. R.,Song, K.,Mikheev, E.,Lee, S.,Stemmer, S.,Tenne, D. A.,Oh, S. H.,Tsymbal, E. Y.,Wu, X.,Chen, L.-Q.,Gruverman, A.,Eom, C. B. American Association for the Advancement of Scienc 2015 Science Vol.349 No.6254

<P><B>Thinning films induces ferroelectricity</B></P><P>Thin ferroelectric films are needed in computers and medical devices. However, traditional ferroelectric films typically become less and less polarized the thinner the films become. Instead of using a good ferroelectric and making it thinner, Lee <I>et al.</I> started with SrTiO<SUP>3</SUP>, which in its bulk form is not ferroelectric. This material does have naturally occurring nanosized polarized regions. and when the thickness of the SrTiO<SUB>3</SUB> films reaches the typical size of these regions, the whole film aligns and becomes ferroelectric.</P><P><I>Science</I>, this issue p. 1314</P><P>The enhancement of the functional properties of materials at reduced dimensions is crucial for continuous advancements in nanoelectronic applications. Here, we report that the scale reduction leads to the emergence of an important functional property, ferroelectricity, challenging the long-standing notion that ferroelectricity is inevitably suppressed at the scale of a few nanometers. A combination of theoretical calculations, electrical measurements, and structural analyses provides evidence of room-temperature ferroelectricity in strain-free epitaxial nanometer-thick films of otherwise nonferroelectric strontium titanate (SrTiO<SUB>3</SUB>). We show that electrically induced alignment of naturally existing polar nanoregions is responsible for the appearance of a stable net ferroelectric polarization in these films. This finding can be useful for the development of low-dimensional material systems with enhanced functional properties relevant to emerging nanoelectronic devices.</P>

Temperature-Dependent Photoluminescence from ZnO/Zn0.85Mg0.15O Heterostructure Grown on Si(111) Substrates

L. P. Zhu,X. Q. Gu,H. P. He,F. Huang,M. X. Qiu,Z. Z. Ye,Y. Z. Zhang,B. H. Zhao 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

A ZnO/Zn0.85Mg0.15O single quantum well (SQW) was fabricated on a Si(111) substrate by using a pulsed laser deposition (PLD) technique. Photoluminescence (PL) measurements were carried out in the range of 10 − 290 K in order to investigate the mechanism of carrier dynamics. At 10 K, the sample exhibited two predominant ultraviolet emissions, one at 3.57 eV and the other at 3.38 eV, which were attributed to recombinations of localized excitons (LE band) in the barrier and the well layers, respectively. The quantum well emission showed a blue shift of nearly 20 meV with respect to the epitaxial ZnO films. We also observed that the carrier localization resulted in an “S-shaped” red-blue-red shift of the ∽3.38 eV emission with increasing temperature. A ZnO/Zn0.85Mg0.15O single quantum well (SQW) was fabricated on a Si(111) substrate by using a pulsed laser deposition (PLD) technique. Photoluminescence (PL) measurements were carried out in the range of 10 − 290 K in order to investigate the mechanism of carrier dynamics. At 10 K, the sample exhibited two predominant ultraviolet emissions, one at 3.57 eV and the other at 3.38 eV, which were attributed to recombinations of localized excitons (LE band) in the barrier and the well layers, respectively. The quantum well emission showed a blue shift of nearly 20 meV with respect to the epitaxial ZnO films. We also observed that the carrier localization resulted in an “S-shaped” red-blue-red shift of the ∽3.38 eV emission with increasing temperature.

Internet Roundtrip Delay Prediction Using the Maximum Entropy Principle

Liu, Peter Xiaoping,Meng, Max Q-H,Gu, Jason The Korea Institute of Information and Commucation 2003 Journal of communications and networks Vol.5 No.1

Internet roundtrip delay/time (RTT) prediction plays an important role in detecting packet losses in reliable transport protocols for traditional web applications and determining proper transmission rates in many rate-based TCP-friendly protocols for Internet-based real-time applications. The widely adopted autoregressive and moving average (ARMA) model with fixed-parameters is shown to be insufficient for all scenarios due to its intrinsic limitation that it filters out all high-frequency components of RTT dynamics. In this paper, we introduce a novel parameter-varying RTT model for Internet roundtrip time prediction based on the information theory and the maximum entropy principle (MEP). Since the coefficients of the proposed RTT model are updated dynamically, the model is adaptive and it tracks RTT dynamics rapidly. The results of our experiments show that the MEP algorithm works better than the ARMA method in both RTT prediction and RTO estimation.

New approaches to testing and evaluating the impact capability of coal seam with hard roof and/or floor in coal mines

Tan, Y.L.,Liu, X.S.,Shen, B.,Ning, J.G.,Gu, Q.H. Techno-Press 2018 Geomechanics & engineering Vol.14 No.4

Samples composed of coal and rock show different mechanical properties of the pure coal or rock mass. For the same coal seam with different surrounding rocks, the frequency and intensity of rock burst can be significantly different in. First, a method of measuring the strain variation of coal in the coal-rock combined sample was proposed. Second, laboratory tests have been conducted to investigate the influences of rock lithologies, combined forms and coal-rock height ratios on the deformation and failure characteristics of the coal section using this method. Third, a new bursting liability index named combined coal-rock impact energy speed index (CRIES) was proposed. This index considers not only the time effect of energy, but also the influence of surrounding rocks. At last, a new approach considering the influences of roof and/or floor was proposed to evaluate the impact capability of coal seam. Results show that the strength and elastic modulus of coal section increase significantly with the coal-rock height ratio decreasing. In addition, the values of bursting liability indexes of the same coal seam vary greatly when using the new approach. This study not only provides a new approach to measuring the strain of the coal section in coal-rock combined sample, but also improves the evaluation system for evaluating the impact capability of coal.