Sub 15 fs X ray pump and X ray probe experiment for the study of ultrafast magnetization dynamics in ferromagnetic alloys

In this paper, we present a new setup for the measurement of element specific ultrafast magnetization dynamics in ferromagnetic thin films with a sub 15 fs time resolution. Our experiment relies on a split and delay approach which allows us to fully exploit the shortest X rays pulses delivered by X ray Free Electrons Lasers close to the attosecond range , in an X ray pump X ray probe geometry. The setup performance is demonstrated by measuring the ultrafast elemental response of Ni and Fe during demagnetization of ferromagnetic Ni and Ni80Fe20 Permalloy samples upon resonant excitation at the corresponding absorption edges. The transient demagnetization process is measured in both reflection and transmission geometry using, respectively, the transverse magneto optical Kerr effect T MOKE and the Faraday effect as probing mechanism

Toward ultrafast magnetic depth profiling using time resolved x ray resonant magnetic reflectivity

During the last two decades, a variety of models have been developed to explain the ultrafast quenching of magnetization following femtosecond optical excitation. These models can be classified into two broad categories, relying either on a local or a non local transfer of angular momentum. The acquisition of the magnetic depth profiles with femtosecond resolution, using time resolved x ray resonant magnetic reflectivity, can distinguish local and non local effects. Here, we demonstrate the feasibility of this technique in a pump probe geometry using a custom built reflectometer at the FLASH2 free electron laser FEL . Although FLASH2 is limited to the production of photons with a fundamental wavelength of 4 amp; 8201;nm amp; 8771;310 amp; 8201;eV , we were able to probe close to the Fe L3 edge 706.8 amp; 8201;eV of a magnetic thin film employing the third harmonic of the FEL. Our approach allows us to extract structural and magnetic asymmetry signals revealing two dynamics on different time scales which underpin a non homogeneous loss of magnetization and a significant dilation of 2 amp; 8201; of the layer thickness followed by oscillations. Future analysis of the data will pave the way to a full quantitative description of the transient magnetic depth profile combining femtosecond with nanometer resolution, which will provide further insight into the microscopic mechanisms underlying ultrafast demagnetizatio

A tool for predicting the thermal performance of a diesel engine

This paper presents a thermal network model for the simulation of the transient response of diesel engines. The model was adjusted by using experimental data from a completely instrumented engine run under steady-state and transient conditions. Comparisons between measured and predicted material temperatures over a wide range of engine running conditions show a mean error of 7◦C. The model was then used to predict the thermal behavior of a different engine. Model results were checked against oil and coolant temperatures measured during engine warm-up at constant speed and load, and on a New European Driving Cycle. Results show that the model predicts these temperatures with a maximum error of 3◦C.Torregrosa, AJ.; Olmeda González, PC.; Martín Díaz, J.; Romero Piedrahita, CA. (2011). A tool for predicting the thermal performance of a diesel engine. Heat Transfer Engineering. 32(10):891-904. doi:10.1080/01457632.2011.548639S891904321

Immunological evidence for common antigenic sites in high-density lipoproteins from rainbow trout and man.

The plasma high-density lipoproteins (HDL, rho 1.085-1.21 g/ml) of rainbow trout (Salmo gairdneri) have been shown to contain large amounts of apolipoprotein (apo) AI (Mr 28,000) and several other apolipoproteins of Mr less than 14,000 (apo C-like) and of Mr 37,000-38,000, 44,000-45,000 and 53,000-54,000. Comparison of apo AI from trout and human HDL shows them to be similar in Mr and to have some cross-immunoreactivity, whereas apo AII differs in Mr but also possesses common antigenic sites. It is suggested that the major apolipoproteins of fish and human HDL may fulfil similar roles in lipid transport