522 research outputs found

    Effect of low intensity white light irradiation on the retinas of mice

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    AIM: To investigate the effect of low intensity white light irradiation on the retinas of mice.<p>METHODS: Thirty C57BL/6J mice were randomly divided into two groups. The number of the mice in each group was 15. The mice in experimental group received dark adaptation from 5:00p.m. to 6:00p.m.,and then exposed to LED white light from 6:00p.m. to 7:00p.m. everyday for a month. At 1, 3, 7, 14 and 30d after the beginning, we examed the histology of mice retinas, calculated the thickness of outer nuclear layer(ONL),inner nuclear layer(INL)and analyzed electrophysiology of mice.<p>RESULTS:One month after experiment, compared to the control group, the latency of Rod-R a wave of the mice in experimental group significantly prolonged, the amplitude of Cone-R b wave of the mice in experimental group significantly decreased and the latency of b wave of the mice in experimental group significantly prolonged(<i>P</i><0.05).There are no significant difference in the histology of retina, ONL and INL thicknesses.<p>CONCLUSION: 100lux low intensity white light could give rise to the impairment of the retinal functions in dark-adapted mice

    Intra-Storm Temporal Patterns of Rainfall in China Using Huff Curves

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    Intra-storm temporal distributions of precipitation are important for infiltration, runoff, and erosion process understanding and models. A convenient and established method for characterizing precipitation hyetographs is the use of non-dimensional Huff curves. In this study, 11,801 erosive rainfall events with 1 min resolution data collected over 30 to 40 years from 18 weather stations located across the central and eastern parts of China were analyzed to produce Huff curves. Each event was classified according to the quartile period within the event that contained the greatest fraction of rainfall. The results showed that 38.3% of events had the maximum rainfall amounts in the first quartile, followed by the second (26.8%), third (22.4%), and fourth (12.5%) quartiles. Quartile I and II events were generally characteristic of shorter duration and heavier intensity events. Quartile I events averaged 23% shorter durations than quartile IV events, whereas the mean intensity (Iavg), mean maximum 30 min intensity (I30), and mean rainfall erosivity index (EI30) were 1.71, 1.22, and 1.23 times greater, respectively, than those for quartile IV and were significant at a 5% level based on two-sample t-tests. The proportion of quartile I events was less for events of longer duration, whereas the proportions of quartile III and IV events were greater. Two-sample Kolmogorov-Smirnov tests suggested that regional Huff curves can be derived for the central and eastern parts of China. Regional Huff curves developed in this study exhibited dissimilarities in terms of the percentages of storms for different quartiles and the shapes of the curves compared to those reported for Illinois, peninsular Malaysia, and Santa Catarina in Brazil

    Discovery potential for the LHCb fully-charm tetraquark X(6900)X(6900) state via pˉp\bar{p}p annihilation reaction

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    Inspired by the observation of the fully-charm tetraquark X(6900)X(6900) state at LHCb, the production of X(6900)X(6900) in pˉpJ/ψJ/ψ\bar{p}p\rightarrow J/\psi J/\psi reaction is studied within an effective Lagrangian approach and Breit-Wigner formula. The numerical results show that the cross section of X(6900)X(6900) at the c.m. energy of 6.9 GeV is much larger than that from the background contribution. Moreover, we estimate dozens of signal events can be detected by D0 experiment, which indicates that searching for the X(6900)X(6900) via antiproton-proton scattering may be a very important and promising way. Therefore, related experiments are suggested to be carried out.Comment: 4 pages, 2 figure

    Resonant spin Hall conductance in quantum Hall systems lacking bulk and structural inversion symmetry

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    Following a previous work [Shen, Ma, Xie and Zhang, Phys. Rev. Lett. 92, 256603 (2004)] on the resonant spin Hall effect, we present detailed calculations of the spin Hall conductance in two-dimensional quantum wells in a strong perpendicular magnetic field. The Rashba coupling, generated by spin-orbit interaction in wells lacking bulk inversion symmetry, introduces a degeneracy of Zeeman-split Landau levels at certain magnetic fields. This degeneracy, if occuring at the Fermi energy, will induce a resonance in the spin Hall conductance below a characteristic temperature of order of the Zeeman energy. At very low temperatures, the spin Hall current is highly non-ohmic. The Dresselhaus coupling due to the lack of structure inversion symmetry partially or completely suppresses the spin Hall resonance. The condition for the resonant spin Hall conductance in the presence of both Rashba and Dresselhaus couplings is derived using a perturbation method. In the presence of disorder, we argue that the resonant spin Hall conductance occurs when the two Zeeman split extended states near the Fermi level becomes degenerate due to the Rashba coupling and that the the quantized charge Hall conductance changes by 2e^2/h instead of e^2/h as the magnetic field changes through the resonant field.Comment: 9 pages, 7 figures. This is a sequel to Physical Review Letters 90, 256603 (2004

    6-Chloro-3-nitro-N-(propan-2-yl)pyridin-2-amine

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    There are two mol­ecules in the asymmetric unit mol­ecule of the title compound, C8H10ClN3O2. Intra­molecular N—H⋯O hydrogen bonds stabilize the mol­ecular structure. There are no classical inter­molecular hydrogen bonds in the crystal structure

    Diaqua­bis­(3-nitro­benzoato-κO 1)bis­[1H-5-(3-pyrid­yl)-3-(4-pyrid­yl)-1H-1,2,4-triazole-κN 5]cobalt(II) dihydrate

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    In the centrosymmetric title compound, [Co(C7H4NO4)2(C12H9N5)2(H2O)2]·2H2O, the CoII atom, located on an inversion center, is coordinated by two N atoms [Co—N = 2.155 (3) Å] and four O atoms [Co—O = 2.099 (2)–2.117 (3) Å] in a distorted octa­hedral geometry. Inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the components into a three-dimensional supramolecular framework

    C/EBP-α, involvement of a novel transcription factor in leptin-induced VCAM-1 production in mouse chondrocytes

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    AbstractLeptin and vascular cell adhesion molecules-1 (VCAM-1) are two important mediators in obesity-related osteoarthritis, while the molecular mechanism linking leptin to VCAM-1 production is still obscure. Here we show that leptin upregulates VCAM-1 mRNA and protein levels in a time- and dose-dependent manner. Mechanistically, leptin induces VCAM-1 promoter activity by increasing the expression of C/EBP-α and facilitating its binding to a newly identified element in the VCAM-1 gene. Gain or loss of function studies reveal a regulatory role of C/EBP-α on VCAM-1 expression. Finally, elevated plasma leptin level correlates to increased C/EBP-α and VCAM-1 production in chondrocytes from obese mice

    Poly[[(4,4′-bipyridine-κN)[μ3-(S)-2-hy­droxy­butane­dioato-κ4 O 1,O 2:O 4:O 4′]zinc] dihydrate]

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    In the title compound, {[Zn(C4H4O5)(C10H8N2)]·2H2O}n, the ZnII ion displays a distorted tetra­gonal–pyramidal coordination environment with one hy­droxy O and three carboxyl­ate O atoms from three malate anions, and the one remaining position occupied by an N atom from a 4,4′-bipyridine ligand. The pyridine rings of the 4,4′-bipyridine ligand are twisted with respect to each other by a dihedral angle of 35.8 (2)°. The uncoordinated water mol­ecules are linked to the complex mol­ecules by O—H⋯O hydrogen bonds. Each malate anion forms four coordination bonds with three Zn atoms, establishing a layer structure parallel to the ac plane. Adjacent layers are further linked via O—H⋯N hydrogen bonding. π–π stacking between the pyridine rings [face-to-face distance = 3.651 (3) Å] occurs in the crystal structure
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