Effects of mixed volatile fatty acid sodium salt on insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-3 (IGFBP-3) in plasma and rumen tissue, and rumen epithelium development in lambs

Fifteen cross-bred male lambs (Dorset × Small Tail Han), aged 7 weeks, with average liveweight of 13.8±0.8 kg, were used to study effects of feeding mixed volatile fatty acid (VFA) sodium salt on insulin-like growth factor-I (IGF-I), insulin-like growth factor-binding protein-3 (IGFBP-3) in plasma and rumen tissue and rumen epithelium development. The lambs were randomly divided into 5 groups with 3 lambs in each group. Graded levels of mixed VFA sodium salt (the molar proportion of acetate, propionate, and butyrate was 65:25:10), i.e. 0, 5, 15, 30 and 60g/d was added into milk replacer as experimental treatments I, II, III, IV and V, respectively. The trial lasted 24 days. No differences were found in plasma IGF-I and IGFBP-3 between different treatments (P>0.05), or in IGF-I and IGFBP-3 in rumen dorsal sac and in IGF-I in ventral sac between different treatments (P>0.05), while IGFBP- 3 of treatments IV and V was higher than other treatments in ventral sac (P<0.05). In rumen dorsal sac, the length and density of rumen papillae of treatments III, IV and V were higher than treatment I (P<0.05) while no differences were found in the width and surface area of rumen papillae between different treatments or in length, width, density and surface area of rumen papillae in ventral sac between different treatments (P>0.05). It was concluded that feeding mixed VFA sodium salt up to 60 g/d per lamb in milk replacer had no significant effect on development of rumen epithelium.Key words: volatile fatty acid sodium salt; insulin-like growth factor-I (IGF-I); insulin-like growth factor-binding protein-3 (IGFBP-3); rumen epithelium; lambs

Ozone production in four major cities of China: sensitivity to ozone precursors and heterogeneous processes

Abstract. Despite a large volume of research over a number of years, our understandings of the key precursors that control tropospheric ozone production and the impacts of heterogeneous processes remain incomplete. In this study, we analyze measurements of ozone and its precursors made at rural/suburban sites downwind of four large Chinese cities – Beijing, Shanghai, Guangzhou and Lanzhou. At each site the same measurement techniques were utilized and a photochemical box model based on the Master Chemical Mechanism (v3.2) was applied, to minimize uncertainties in comparison of the results due to differences in methodology. All four cities suffered from severe ozone pollution. At the rural site of Beijing, export of the well-processed urban plumes contributed to the extremely high ozone levels (up to an hourly value of 286 ppbv), while the pollution observed at the suburban sites of Shanghai, Guangzhou and Lanzhou was characterized by intense in-situ ozone production. The major anthropogenic hydrocarbons were alkenes and aromatics in Beijing and Shanghai, aromatics in Guangzhou, and alkenes in Lanzhou. The ozone production was found to be in a VOCs-limited regime in both Shanghai and Guangzhou, and a mixed regime in Lanzhou. In Shanghai, the ozone formation was most sensitive to aromatics and alkenes, while in Guangzhou aromatics were the predominant ozone precursors. In Lanzhou, either controlling NOx or reducing emissions of olefins from the petrochemical industry would mitigate the local ozone production. The potential impacts of several heterogeneous processes on the ozone formation were assessed. The hydrolysis of dinitrogen pentoxide (N2O5), uptake of the hydroperoxyl radical (HO2) on particles, and surface reactions of NO2 forming nitrous acid (HONO) present considerable sources of uncertainty in the current studies of ozone chemistry. Further efforts are urgently required to better understand these processes and refine atmospheric models

Deep level transient spectroscopic study of oxygen implanted melt grown ZnO single crystal

Deep level traps in melt grown ZnO single crystal created by oxygen implantation and subsequent annealing in air were studied by deep level transient spectroscopy measurement between 80 and 300 K. The E C-0.29 eV trap (E3) was the dominant peak in the as-grown sample and no new defects were created in the as-O-implanted sample. The single peak feature of the deep level transient spectroscopy (DLTS) spectra did not change with the annealing temperature up to 750 °C, but the activation energy decreased to 0.22 eV. This was explained in terms of a thermally induced defect having a peak close to but inseparable from the original 0.29 eV peak. A systematic study on a wide range of the rate window for the DLTS measurement successfully separated the Arrhenius plot data originated from different traps. It was inferred that the E3 concentration in the samples did not change after the O-implantation. The traps at E C-0.11, E C-0.16 and E C-0.58 eV were created after annealing. The E C-0.16 eV trap was assigned to an intrinsic defect. No DLTS signal was found after the sample was annealed to 1200 °C. © 2011 IOP Publishing Ltd.postprin

结合遗传算法的LVQ神经网络在声学底质分类中的应用

Author name used in this publication: 唐秋华Author name used in this publication: 刘保华Author name used in this publication:Author name used in this publication: 陈永奇Author name used in this publication: 周兴华Author name used in this publication: 丁继胜Title in Traditional Chinese: 結合遺傳算法的LVQ神經網絡在聲學底質分類中的應用Journal title in Traditional Chinese: 地球物理學報2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

基于自组织神经网络的声学底质分类研究

Author name used in this publication: 唐秋华Author name used in this publication: 刘保华Author name used in this publication: 陈永奇Author name used in this publication: 周兴华Author name used in this publication: 丁继胜Title in Traditional Chinese: 基于自組織神經網絡的聲學底質分類研究Journal title in Traditional Chinese: 聲學技術2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and superconductivity remains unclear in the underdoped regime, which is closer to the antiferromagnetic phase. Here we report that the superconducting gap of the underdoped pnictides scales linearly with the transition temperature, and that a distinct pseudogap coexisting with the SC gap develops on underdoping. This pseudogap occurs on Fermi surface sheets connected by the antiferromagnetic wavevector, where the superconducting pairing is stronger as well, suggesting that antiferromagnetic fluctuations drive both the pseudogap and superconductivity. Interestingly, we found that the pseudogap and the spectral lineshape vary with the Fermi surface quasi-nesting conditions in a fashion that shares similarities with the nodal-antinodal dichotomous behaviour observed in underdoped copper oxide superconductors.Comment: Main Manuscript: 19 pages, 3 figures; Supplementary Information: 10 pages, 7 figure

(pi,pi)-electronic order in iron arsenide superconductors

The distribution of valence electrons in metals usually follows the symmetry of an ionic lattice. Modulations of this distribution often occur when those electrons are not stable with respect to a new electronic order, such as spin or charge density waves. Electron density waves have been observed in many families of superconductors[1-3], and are often considered to be essential for superconductivity to exist[4]. Recent measurements[5-9] seem to show that the properties of the iron pnictides[10, 11] are in good agreement with band structure calculations that do not include additional ordering, implying no relation between density waves and superconductivity in those materials[12-15]. Here we report that the electronic structure of Ba1-xKxFe2As2 is in sharp disagreement with those band structure calculations[12-15], instead revealing a reconstruction characterized by a (pi,pi) wave vector. This electronic order coexists with superconductivity and persists up to room temperature

Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat

The symmetry and structure of the superconducting gap in the Fe-based superconductors are the central issue for understanding these novel materials. So far the experimental data and theoretical models have been highly controversial. Some experiments favor two or more constant or nearly-constant gaps, others indicate strong anisotropy and yet others suggest gap zeros ("nodes"). Theoretical models also vary, suggesting that the absence or presence of the nodes depends quantitatively on the model parameters. An opinion that has gained substantial currency is that the gap structure, unlike all other known superconductors, including cuprates, may be different in different compounds within the same family. A unique method for addressing this issue, one of the very few methods that are bulk and angle-resolved, calls for measuring the electronic specific heat in a rotating magnetic field, as a function of field orientation with respect to the crystallographic axes. In this Communication we present the first such measurement for an Fe-based high-Tc superconductor (FeBSC). We observed a fourfold oscillation of the specific heat as a function of the in-plane magnetic field direction, which allowed us to identify the locations of the gap minima (or nodes) on the Fermi surface. Our results are consistent with the expectations of an extended s-wave model with a significant gap anisotropy on the electron pockets and the gap minima along the \Gamma M (or Fe-Fe bond) direction.Comment: 32 pages, 7 figure

Pacific warm pool excitation, earth rotation and El Niño southern oscillations

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)

The low energy band structure and Fermi surface of the newly discovered superconductor, AxFe2Se2 (A=K,Cs), have been studied by angle-resolved photoemission spectroscopy. Compared with iron pnictide superconductors, AxFe2Se2 (A=K,Cs) is the most heavily electron-doped with Tc~30 K. Only electron pockets are observed with an almost isotropic superconducting gap of ~10.3 meV, while there is no hole Fermi surface near the zone center, which indicates the inter-pocket hopping or Fermi surface nesting is not a necessary ingredient for the unconventional superconductivity in iron-based superconductors. Thus, the sign changed s$_\pm$ pairing symmetry, a leading candidate proposed for iron-based superconductors, becomes conceptually irrelevant in describing the superconducting state here. A more conventional s-wave pairing is a better description.Comment: 4 pages, 4 figures, published online in Nature Materials 201