Magnetic domain structure and dynamics in interacting ferromagnetic stacks with perpendicular anisotropy

The time and field dependence of the magnetic domain structure at magnetization reversal were investigated by Kerr microscopy in interacting ferromagnetic Co/Pt multilayers with perpendicular anisotropy. Large local inhomogeneous magnetostatic fields favor mirroring domain structures and domain decoration by rings of opposite magnetization. The long range nature of these magnetostatic interactions gives rise to ultra-slow dynamics even in zero applied field, i.e. it affects the long time domain stability. Due to this additionnal interaction field, the magnetization reversal under short magnetic field pulses differs markedly from the well-known slow dynamic behavior. Namely, in high field, the magnetization of the coupled harder layer has been observed to reverse more rapidly by domain wall motion than the softer layer alone.Comment: 42 pages including 17 figures. submitted to JA

Thermoelectric cross-plane properties on p- and n-Ge/SixGe1-x superlattices

Silicon and germanium materials have demonstrated an increasing attraction for energy harvesting, due to their sustainability and integrability with complementary metal oxide semiconductor and micro-electro-mechanical-system technology. The thermoelectric efficiencies for these materials, however, are very poor at room temperature and so it is necessary to engineer them in order to compete with telluride based materials, which have demonstrated at room temperature the highest performances in literature [1]. Micro-fabricated devices consisting of mesa structures with integrated heaters, thermometers and Ohmic contacts were used to extract the cross-plane values of the Seebeck coefficient and the thermal conductivity from p- and n-Ge/SixGe1-x superlattices. A second device consisting in a modified circular transfer line method structure was used to extract the electrical conductivity of the materials. A range of p-Ge/Si0.5Ge0.5 superlattices with different doping levels was investigated in detail to determine the role of the doping density in dictating the thermoelectric properties. A second set of n-Ge/Si0.3Ge0.7 superlattices was fabricated to study the impact that quantum well thickness might have on the two thermoelectric figures of merit, and also to demonstrate a further reduction of the thermal conductivity by scattering phonons at different wavelengths. This technique has demonstrated to lower the thermal conductivity by a 25% by adding different barrier thicknesses per period

MVDC for utility scale power distribution and control

This poster outlines the case for converting selected network assets to medium voltage dc to increase network performance via a series of load flow studies. Technology readiness level and research requirements for the technology are also outlined

Highly asymmetric magnetic domain wall propagation due to coupling to a periodic pinning potential

Magneto-optical microscopy and magnetometry have been used to study 19 magnetization reversal in an ultrathin magnetically soft [Pt/Co]2 ferromagnetic film 20 coupled to an array of magnetically harder [Co/Pt]4 nanodots via a predominantly 21 dipolar interaction across a 3 nm Pt spacer. This interaction generates a spatially 22 periodic pinning potential for domain walls propagating through the continuous 23 magnetic film. When reversing the applied field with respect to the static nanodot 24 array magnetization orientation, strong asymmetries in the wall velocity and switching 25 fields are observed. Asymmetric switching fields mean that the hysteresis of the film is 26 characterized by a large bias field of dipolar origin which is linked to the wall velocity 27 asymmetry. This latter asymmetry, though large at low fields, vanishes at high fields 28 where the domains become round and compact. A field-polarity-controlled transition 29 from dendritic to compact faceted domain structures is also seen at low field and a 30 model is proposed to interpret the transition

Prediction of lung exposure to anti-tubercular drugs using plasma pharmacokinetic data: implications for dose selection

The development of novel candidate molecules for tuberculosis remains challenging, as drug distribution into the target tissue is not fully characterised in preclinical models of infection. Often antitubercular human dose selection is derived from pharmacokinetic data in plasma. Here, we explore whether whole-body physiologically-based pharmacokinetic (PBPK) modelling enables the prediction of lung exposure to anti-tubercular drugs in humans. Whole-body PBPK models were developed for rifampicin, isoniazid, pyrazinamide, and ethambutol using plasma data in mice as basis for the prediction of lung exposure. Model parameters were subsequently used to extrapolate disposition properties from mouse and determine lung:plasma ratio in humans. Model predictions were compared to biopsy data from patients. Predictions were deemed adequate if they fell within two-fold range of the observations. The concentration vs time profiles in lung were adequately predicted in mice. Isoniazid and pyrazinamide lung exposures were predicted to be comparable to plasma levels, whereas ethambutol lung exposure was predicted to be higher than in plasma. Lung:plasma ratio in humans could be reasonably predicted from preclinical data, but was highly dependent on the distribution model. This analysis showed that plasma pharmacokinetics may be used in conjunction with PBPK modelling to derive lung tissue exposure in mice and humans during early lead optimisation phase. However, the impact of uncertainty in predicted tissue exposure due to distribution should be always investigated through a sensitivity analysis when only plasma data is available. Despite these limitations, insight into lung tissue distribution represents a critical step for the dose rationale in tuberculosis patients

Development of RT-semi-nested PCR for detection of hepatitis A virus in stool in epidemic conditions.

The purpose of this study was to determine the efficiency of semi-nested PCR in detecting hepatitis A virus (HAV) RNA. During a 2-year period (1990-1991), HAV RNA was searched for in shellfish from the French Brittany coasts using cRNA and vRNA probes. In January 1992, at the time of a hepatitis A outbreak, 28 stool samples were collected from infected patients (18 adults, 10 children) with anti-HAV IgM. Four samples from subjects with negative HAV serology were used as negative controls. Nucleic acid amplification (reverse-transcription-semi-nested PCR) was performed to detect HAV in stool. HAV RNA was purified by phenol-chloroform extraction and converted to cDNA using reverse transcriptase (Mu-MLV). After amplification, PCR products were visualized on an ethidium-bromide-stained gel and confirmed by hybridization with a specific digoxigenin-labelled oligoprobe. Samples were also studied by molecular hybridization with cRNA and vRNA probes. After onset of the illness, HAV RNA was detected over a longer time period by semi-nested PCR (16/28) than by hybridization (0/28). Even though biological diagnosis of hepatitis A will continue to rely on the detection of anti-HAV IgM, PCR should be useful in certain clinical cases (diagnosis of relapse) and for epidemiological and environmental monitoring of viruses

Grasses control strategies in setting restoration stand of the Atlantic Forest.

This study aimed to assess the effectiveness of four weed control strategies in forest setting stands linked by a set of Atlantic Forest tree species. Four treatments were employed: mechanical ? manual hoeing and mowing; chemical ? glyphosate herbicide application in the total area; chemical ? cultural ? herbicide spraying and herbaceous legume intercropping; chemical-mechanical ? herbicide planting in rows and mowing in the interrows. Diameter, crown area and soil cover percentage of the eight tree species were assessed at 18 months. Herbicide spraying in total area promoted the greatest reduction in weed populations, as well as superior growth in height, diameter, crown area and soil cover of the tree species. More interventions were necessary in the treatment of mechanical weed control that has also shown the least growth of the tree species. The chemical method was the most effective in weed control and promoted the greatest growth of the tree speci