Simulations of a single membrane between two walls using a Monte Carlo method

Quantitative theory of interbilayer interactions is essential to interpret x-ray scattering data and to elucidate these interactions for biologically relevant systems. For this purpose Monte Carlo simulations have been performed to obtain pressure P and positional fluctuations sigma. A new method, called Fourier Monte-Carlo (FMC), that is based on a Fourier representation of the displacement field, is developed and its superiority over the standard method is demonstrated. The FMC method is applied to simulating a single membrane between two hard walls, which models a stack of lipid bilayer membranes with non-harmonic interactions. Finite size scaling is demonstrated and used to obtain accurate values for P and sigma in the limit of a large continuous membrane. The results are compared with perturbation theory approximations, and numerical differences are found in the non-harmonic case. Therefore, the FMC method, rather than the approximations, should be used for establishing the connection between model potentials and observable quantities, as well as for pure modeling purposes.Comment: 10 pages, 10 figure

NF-κB Induced the Donor Liver Cold Preservation Related Acute Lung Injury in Rat Liver Transplantation Model

We have observed at our clinical work that acute lung injury (ALI) often occurs in patients transplanted with donor livers persevered for long time. So, we conducted this study to investigate the influence of cold preservation time (CPT) of donor liver on ALI induced by liver transplantation (LT), and further study the role of nuclear factor-κB (NF-κB) in the process.Wistar rats were used as donors and recipients to establish orthotopic rat liver transplantation models. Donor livers were preserved at 4°C for different lengths of time. The effect of NF-κB inhibitor, ammonium pyrrolidinedithiocarbamate (PDTC), on ALI was detected. All samples were harvested after 3 h reperfusion. The severity of liver injury was evaluated first. The expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in liver tissue and liver outflow serum were measured respectively. The severity indexes of ALI, the activity of NF-κB and inhibitor-κBα (I-κBα) in lung/liver were measured accordingly.With the prolonged liver CPT, the liver damage associated indexes and ALI-related indexes all increased significantly. TNF-α and IL-1β in liver outflow serum increased accordingly, and the activity of NF-κB in liver/lung increased correspondingly. All these ALI-associated indexes could be partially reversed by the use of PDTC.Extended CPT aggravates the damage of donor liver and induces the expressions of TNF-α and IL-1β in liver. These inflammatory factors migrate to lung via liver outflow blood and activate NF-κB in lung, inducing ALI finally. NF-κB may play a critical role in LT-related ALI. Patients with or at risk of ALI may benefit from acute anti-inflammatory treatment with PDTC

Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O + 232Th reaction

It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O +  232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model

Decay spectroscopy of Cd-129

Excited states of $^{129}$In populated following the $\beta$-decay of $^{129}$Cd were experimentally studied with the GRIFFIN spectrometer at the ISAC facility of TRIUMF, Canada. A 480-MeV proton beam was impinged on a uranium carbide target and $^{129}$Cd was extracted using the Ion Guide Laser Ion Source (IG-LIS). $\beta$- and $\gamma$-rays following the decay of $^{129}$Cd were detected with the GRIFFIN spectrometer comprising the plastic scintillator SCEPTAR and 16 high-purity germanium (HPGe) clover-type detectors. %, along with the $\beta$-particles were detected with SCEPTAR. From the $\beta$-$\gamma$-$\gamma$ coincidence analysis, 32 new transitions and 7 new excited states were established, expanding the previously known level scheme of $^{129}$In. The $\log ft$ values deduced from the $\beta$-feeding intensities suggest that some of the high-lying states were populated by the $\nu 0 g_{7/2} \rightarrow \pi 0 g_{9/2}$ allowed Gamow-Teller (GT) transition, which indicates that the allowed GT transition is more dominant in the $^{129}$Cd decay than previously reported. Observation of fragmented Gamow-Teller strengths is consistent with theoretical calculations.Comment: 13 pages, 9 figures, to be published in Physical Review