A resonance mechanism of efficient energy transfer mediated by Fenna-Matthews-Olson complex

The Wigner-Weisskopf-type model developed in [R. Alicki and F. Giraldi, J. Phys. B {\bf 44}, 154020 (2011)] is applied to the biological process of energy transfer from a large peripheral light harvesting antenna to the reaction center. This process is mediated by the Fenna-Matthews-Olson (FMO) photosynthetic complex with a remarkably high efficiency. The proposed model provides a simple resonance mechanism of this phenomenon employing exciton coherent motion and described by analytical formulas. A coupling to the vibrational environment is a necessary component of this mechanism as well as a fine tuning of the FMO complex Hamiltonian. The role of the relatively strong coupling to the energy sink in achieving the resonance condition and the absence of heating of the vibrational environment are emphasized.Comment: 13 pages, 4 figure

Irradiation damage on CrNbTaVWx high entropy alloys

ABSTRACT: CrNbTaVWx high-entropy alloys have been developed for plasma facing components to be applied in nuclear fusion reactors. The CrNbTaVWx (x = 1 and 1.7) compositions were prepared by ball milling and consolidated at 1600 degrees C under 90 MPa. To study the irradiation resistance of these materials, deuterium plasmas were used to irradiate the samples in the PF-1000U facility with 1 and 3 discharges. Structural changes before and after irradiation were analyzed by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Nuclear reaction analysis was carried out with 1000 and 2300 keV 3He+ ion beams to evaluate the profile and amount of retained deuterium on the irradiated samples. After irradiation, the sample with higher W content revealed swelling and melting for all discharges, while in the case of CrNbTaVW only blisters were observed. The deuterium retention was higher for CrNbTaVW1.7 when compared with CrNbTaVW for 3 discharges applied.info:eu-repo/semantics/publishedVersio

Mechanical properties and kinetics of boride layers on AISI D2 steel produced by plasma paste boriding

In the present study, the AISI D2 steel has been treated by the plasma paste boriding process using a gas mixture of 70% H2-30% Ar with 70% of borax and 30% SiC. The boriding treatment has been carried out at 700, 750 and 800 °C for an exposure time of 3 to 7 h. The plasma paste borided samples have been investigated by various techniques such as scanning electron microscopy, optical microscopy, XRD analysis, micro-hardness Vickers and the rockwell-C adhesion tests. The fracture toughness has also been measured on the plasma paste borided samples under different values of indentation load. From a kinetic point of view, the boride layers have obeyed the parabolic growth law. The value of boron activation energy for AISI D2 steel has been estimated as 130 kJ mol–1 using our experimental results. In addition, this obtained activation energy has been compared to the literature data

Mechanical properties and kinetics of boride layers on AISI D2 steel produced by plasma paste boriding

221-233In the present study, the AISI D2 steel has been treated by the plasma paste boriding process using a gas mixture of 70% H2-30% Ar with 70% of borax and 30% SiC. The boriding treatment has been carried out at 700, 750 and 800 °C for an exposure time of 3 to 7 h. The plasma paste borided samples have been investigated by various techniques such as scanning electron microscopy, optical microscopy, XRD analysis, micro-hardness Vickers and the rockwell-C adhesion tests. The fracture toughness has also been measured on the plasma paste borided samples under different values of indentation load. From a kinetic point of view, the boride layers have obeyed the parabolic growth law. The value of boron activation energy for AISI D2 steel has been estimated as 130 kJ mol–1 using our experimental results. In addition, this obtained activation energy has been compared to the literature data