Magnetic anisotropy of FePt nanoparticles

We carry out a systematic theoretical investigation of Magneto Crystalline Anisotropy (MCA) of L10 FePt clusters with alternating Fe and Pt planes along the (001) direction. We calculate the structural relaxation and magnetic moment of each cluster by using ab initio spin-polarized density functional theory (DFT), and the MCA with both spin-polarized DFT (including spin-orbit coupling self-consistently) and the torque method. We find that the MCA of any composite structure of a given size is enhanced with respect to that of the same-sized pure Pt or pure Fe cluster as well as to that of any pair of Fe and Pt atoms in bulk L10 FePt. This enhancement results from the hybridization we observe between the 3d orbital of the Fe atoms and the 5d orbital of their Pt neighbors. This hybridization, however, affects the electronic properties of the component atoms in significantly different ways. While it somewhat increases the spin moment of the Fe atoms, it has little effect on their orbital moment; at the same time, it greatly increases both the spin and orbital moment of the Pt atoms. Given the fact that the spin-orbit coupling (SOC) constant of Pt is about 7 times greater than that of Fe, this Fe-induced jump in the orbital moment of the Pt atoms produces the increase in MCA of the composite structures over that of their pure counterparts. That any composite structure exhibits higher MCA than bulk L10 FePt results from the lower coordination of Pt atoms in the cluster, whether Fe or Pt predominates within it. We also find that bipyramidal clusters whose central layer is Pt have higher MCA than their same-sized counterparts whose central layer is Fe. This results from the fact that Pt atoms in such configurations are coordinated with more Fe atoms than in the latter. By thus participating in more instances of hybridization, they contribute higher orbital moments to the overall MCA of the unit

Miniature Silicon Nanobeam Resonator Tuned by GST Phase Change Material

We report a silicon optical nanobeam resonator with central hole infiltrated with a thin layer of Ge2Sb2Te5 (GST) material. The resonances can be tuned when the GST changes its phases between the amorphous and crystalline states

Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

Local field distribution near corrugated interfaces: Green's function formulation

We have developed a Green's function formalism to compute the local field distribution near an interface separating two media of different dielectric constants. The Maxwell's equations are converted into a surface integral equation; thus it greatly simplifies the solutions and yields accurate results for interfaces of arbitrary shape. The integral equation is solved and the local field distribution is obtained for a periodic interface.Comment: Presented at the Conference on Computational Physics (CCP2000), held at Gold Coast, Australia from 3 - 8, December 2000. To be published in Proceedings of CCP200

Genetic and environmental risk factors for sexual distress and its association with female sexual dysfunction

A. Burri, Q. Rahman and T. Spector (2011). Genetic and environmental risk factors for sexual distress and its association with female sexual dysfunction. Psychological Medicine, 41, pp 2435-2445. Copyright © Cambridge University Press 2011. http://dx.doi.org/10.1017/S003329171100049

Are researchers in Europe European researchers? A study of doctoral researchers at the University of Luxembourg

How doctoral researchers (and their supervisors) experience and conceptualise the process of becoming a researcher and the identifications that are enacted during the process has hitherto been researched only in terms of disciplinary and professional identities. Yet, within Europe, the creation of a common Higher Education Area has a potential impact on the doctoral experience and there is a declared intention to encourage doctoral students to see themselves as European researchers. The University of Luxembourg has policies and characteristics which might be expected to support this direction of development, and this study analyses the nuances of doctoral researcher experiences, at this University, of European and wider international identifications comparing these with policies at European and local levels. The opportunities offered to researchers in Luxembourg to ensure the policies are implemented are considered by participants to be significant. Whether the level of expenditure needed is possible in other countries and universities is an open question but remains a crucial condition for policies to be successful

Crystallization of a Bacterial Single Stranded Annealing DNA Repair Protein

INTRODUCTION: Single-stranded annealing (SSA) proteins bind to single-stranded DNA (ssDNA) and promote the pairing of homologous DNA strands, a process that is involved in the repair of double-stranded breaks. This work focuses on RecT and β protein, from Escherichia coli and bacteriophage lambda, respectively, which are two classic examples of SSA proteins. The human protein Rad52 promotes the same reactions as RecT and β, and is involved in multiple DNA repair pathways. IMPORTANCE: Cells and DNA have mechanisms that repair mutations and failure to do so may lead to cancer. Chemotherapy requires study of repair mechanisms. Therefore, it is important to understand the DNA repair processes of RecT and β. Electron Microscopy studies propose that the proteins form oligomeric rings and helical filaments, but information on the fold of the proteins and the DNA binding sites on the surface of the oligomers is not available. This information can be obtained from high resolution images of a protein’s structure. AIM: The aim of this study is to determine the mechanism by which SSA proteins bind to ssDNA and promote the annealing of complimentary DNA strands. This will increase our general understanding of how proteins recognize and repair damaged sites of DNA in cells. Our approach will employ the powerful technique of x-ray crystallography to determine the three-dimensional structure of SSA proteins at high resolution. This technique requires that the SSA protein be crystallized. METHODS: A sample of RecT or β is purified and screened for initial crystals which are then optimized to grow larger crystals. Once large crystals form, x-ray diffraction is used to solve the three-dimensional atomic structure of the protein, preferably in complex with DNA substrates. CONCLUSION: The first large crystals of RecT that can diffract to 6-7 Angstroms have been formed in the lab, which is a significant step toward understanding the protein repair mechanism, which will ultimately provide a foundation for improved applications in cancer treatment

A Constrained Optimization Approach to Dynamic State Estimation for Power Systems Including PMU and Missing Measurements

In this brief, a hybrid filter algorithm is developed to deal with the state estimation (SE) problem for power systems by taking into account the impact from the phasor measurement units (PMUs). Our aim is to include PMU measurements when designing the dynamic state estimators for power systems with traditional measurements. Also, as data dropouts inevitably occur in the transmission channels of traditional measurements from the meters to the control center, the missing measurement phenomenon is also tackled in the state estimator design. In the framework of extended Kalman filter (EKF) algorithm, the PMU measurements are treated as inequality constraints on the states with the aid of the statistical criterion, and then the addressed SE problem becomes a constrained optimization one based on the probability-maximization method. The resulting constrained optimization problem is then solved using the particle swarm optimization algorithm together with the penalty function approach. The proposed algorithm is applied to estimate the states of the power systems with both traditional and PMU measurements in the presence of probabilistic data missing phenomenon. Extensive simulations are carried out on the IEEE 14-bus test system and it is shown that the proposed algorithm gives much improved estimation performances over the traditional EKF method