Oscillations of Ultralight Dark Photon into Gravitational Waves

The discovery of gravitational waves (GWs) opens a new window for exploring the physics of the early universe. Identifying the source of GWs and their spectra today turn out to be the important tasks so as to assist the experimental detection of stochastic GWs. In this paper, we investigate the oscillations of the ultralight dark photon (ULDP) into GWs in the dark halo. Assuming dark matter is composed of the ULDP and there are primordial dark magnetic fields (PDMFs) arising from the axion inflation and/or the dark phase transition, then the ULDP can oscillate into the GW when it passes through an environment of PDMFs. We derive the local energy density of GWs in the galaxy cluster induced by the instaneous oscillation of ULDP in the PDMFs. These stochastic local GWs exhibit a pulse-like spectrum, with frequency depending on the mass of the ULDP, and can be detected in Pulsar Timing Arrays (PTAs) or future space-based interferometers. We also find that the low-frequency GW signal observed by the NANOGrav collaboration and other PTA experiments can be explained by the oscillation of the ULDP in the PDMFs in the early universe.Comment: 7 pages, 3 figure

Methyl 2-{[2,8-bis­(trifluoro­meth­yl)quinolin-4-yl]­oxy}acetate

In the crystal structure of the title compound, C14H9F6NO3, mol­ecules are connected by inter­molecular C—H⋯O hydrogen bonds. The best planes through the benzene and pyridyl rings make a dihedral angle of 1.59 (12)°

2-Chloro-5-(chloro­meth­yl)pyridine

The title compound, C6H5Cl2N, is almost planar, with an r.m.s. deviation of 0.0146 Å for all atoms except for the 5-choloromethyl Cl atom. The offset Cl atom lies above this plane with a Cl—C—C angle of 111.11 (17)°. In the crystal, mol­ecules are connected via inter­molecular C—H⋯N hydrogen bonds, forming dimers

Modulation of the thermodynamic, kinetic and magnetic properties of the hydrogen monomer on graphene by charge doping

The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on doped graphene layers were studied by ab initio simulations. Electron doping was found to heighten the diffusion potential barrier, while hole doping lowers it. However, both kinds of dopings heighten the desorption potential barrier. The underlying mechanism was revealed by investigating the effect of doping on the bond strength of graphene and on the electron transfer and the coulomb interaction between the hydrogen monomer and graphene. The kinetic properties of H and D monomers on doped graphene layers during both the annealing process (annealing time $t_0 =$300 s) and the constant-rate heating process (heating rate $\alpha =$1.0 K/s) were simulated. Both electron and hole dopings were found to generally increase the desorption temperatures of hydrogen monomers. Electron doping was found to prevent the diffusion of hydrogen monomers, while the hole doping enhances their diffusion. Macroscopic diffusion of hydrogen monomers on graphene can be achieved when the doping-hole density reaches $5.0\times10^{13}$ cm$^{-2}$. The magnetic moment and exchange splitting were found to be reduced by both electron and hole dopings, which was explained by a simple exchange model. The study in this report can further enhance the understanding of the interaction between hydrogen and graphene and is expected to be helpful in the design of hydrogenated-graphene-based devices.Comment: Submitte

Carbohydrate metabolism in grape cultivars that differ in sucrose accumulation

Sugar concentrations and sucrose-metabolism related enzyme activities in berries and leaves were investigated during berry development using grape cultivars with different sucrose concentrations. Sucrose concentration was significantly negatively related to acid invertase activity in berries. Acid invertase showed the lowest activities in berries of high-sucrose cultivars, ‘Honey Juice’ and ‘B180’, and the highest in tracesucrose cultivars, ‘Concord’, ‘Jingxiu’, and ‘Jingya’. Acid invertase activities in berries of low-sucrose cultivar ‘Canadice’ were between high- and trace-sucrose cultivars. There was no significant difference in glucose and fructose concentrations, the activities of neutral invertase, sucrose synthase and sucrose phosphate synthase in berries among high-, low- and trace-sucrose cultivars as acid invertase. Sugar concentrations and sucrose-metabolism related enzymes activities in leaves also did not show such difference among all cultivars. The results suggest that differences in sucrose concentration in berries among grape cultivars mainly be due to acid invertase activity. In addition, the final sucrose concentration in berries at maturity for a grape cultivar might be decided at véraison, and véraison is the key period for sucrose accumulation.

iTRAQ Quantitative Analysis of Multidrug Resistance Mechanisms in Human Gastric Cancer Cells

Multidrug resistance (MDR) is a major obstacle towards a successful treatment of gastric cancer. However, the mechanisms of MDR are intricate and have not been fully understood. To elucidate the molecular mechanisms of MDR in gastric cancer, we employed the proteomic approach of isobaric tags for relative and absolute quantification (iTRAQ), followed by LC-MS/MS, using the vincristine-resistant SGC7901/VCR cell line and its parental SGC7901 cell line as a model. In total, 820 unique proteins were identified and 91 proteins showed to be differentially expressed in SGC7901/VCR compared with SGC7901. Several differentially expressed proteins were further validated by western blot analysis. Furthermore, the association of MVP, one of the highly expressed proteins in SGC7901/VCR, with MDR was verified. Our study is the first application of iTRAQ technology for MDR mechanisms analysis in gastric cancer, and many of the differentially expressed proteins identified have not been linked to MDR in gastric cancer before, which showed the value of this technology in identifying differentially expressed proteins in cancer

Direct evidence for active site-dependent formic acid electro-oxidation by topmost-surface atomic redistribution in a ternary PtPdCu electrocatalyst

The active site-dependent electrochemical formic acid oxidation was evidenced by the increased coverage of Pt in the topmost mixed PtPd alloy layer of ternary PtPdCu upon potential cycling, which demonstrated two catalytic pathways only in one catalyst owing to surface atomic redistribution in an acidic electrolyte environment

Fibrosis progression in interferon treatment-naive Chinese plasma donors with chronic hepatitis C for 20 years: a cohort study

SummaryObjectivesTo evaluate the progression of fibrosis and factors influencing this in interferon (IFN) treatment-naive Chinese plasma donors infected with hepatitis C virus (HCV) for approximately 20 years.MethodsFrom July 2010 to June 2011, we investigated 122 IFN treatment-naive chronic hepatitis C (CHC) patients infected by plasma donation in 1992–1995. Liver fibrosis stage and inflammation grade were evaluated by Metavir and Scheuer scoring systems, respectively.ResultsOne hundred and twenty patients underwent liver biopsy. Liver biopsy was not performed in one patient with cirrhosis due to ascites, and another patient was excluded because of an invalid biopsy specimen. Cirrhosis was observed in three patients (fibrosis stage F4 in two patients revealed by biopsy, and one patient with ascites confirmed by physical and Doppler ultrasound examination). Fibrosis stages F1 and F2 were present in 55 and 50 patients, respectively. The severity of liver inflammation was independently related to moderate to severe fibrosis (F ≥2). Older age and male sex showed an increasing tendency for more severe fibrosis (F3/F4) in the present cohort.ConclusionsBased on histopathology results, the progression of fibrosis in patients with CHC infected by repeated plasma donation is slow after HCV infection of approximately 20 years. Liver inflammation is closely related to the development of moderate to severe liver fibrosis