Non-Volatile Memory Characteristics of Submicrometre Hall Structures Fabricated in Epitaxial Ferromagnetic MnAl Films on GaAs

Hall-effect structures with submicrometre linewidths (<0.3pm) have been fabricated in ferromagnetic thin films of Mn[sub 0.60]Al[sub 0.40] which are epitaxially grown on a GaAs substrate. The MnAl thin films exhibit a perpendicular remanent magnetisation and an extraordinary Hall effect with square hysteretic behaviour. The presence of two distinct stable readout states demonstrates the potential of using ultrasmall ferromagnetic volumes for electrically addressable, nonvolatile storage of digital information

The extraordinary Hall effect in coherent epitaxial tau (Mn,Ni)Al thin films on GaAs

Ultrathin coherent epitaxial films of ferromagnetic tau(Mn,Ni)0.60Al0.40 have been grown by molecular beam epitaxy on GaAs substrates. X-ray scattering and cross-sectional transmission electron microscopy measurements confirm that the c axis of the tetragonal tau unit cell is aligned normal to the (001) GaAs substrate. Measurements of the extraordinary Hall effect (EHE) show that the films are perpendicularly magnetized, exhibiting EHE resistivities saturating in the range of 3.3-7.1 muOMEGA-cm at room temperature. These values of EHE resistivity correspond to signals as large as +7 and -7 mV for the two magnetic states of the film with a measurement current of 1 mA. Switching between the two magnetic states is found to occur at distinct field values that depend on the previously applied maximum field. These observations suggest that the films are magnetically uniform. As such, tau(Mn,Ni)Al films may be an excellent medium for high-density storage of binary information

Epitaxial-tau(Mn,Ni)Al/(Al,Ga)As heterostructures: Magnetic and magneto-optic properties

Ferromagnetic Perpendicularly magnetized epitaxial thin films of tau (Mn,Ni)AI have been successfully grown on AlAs/GaAs heterostructures by molecular beam epitaxy. We have investigated the polar Kerr rotation and magnetization of tau MnAl and (Mn,Ni) Al as a function of Mn and Ni concentration. The largest polar Kerr rotation and remnant magnetization were obtained for Mn0.5Al0.5 thin films with values of 0.16-degrees and 224 emu/cm3, respectively. We observed that the Kerr rotation and magnetization remained constant with Ni additions up to about 12 at. % and subsequently decreased with further Ni additions. We discuss these results and one possible method of enhancing the Kerr rotation

Direct observation of topoisomerase IA gate dynamics

Type IA topoisomerases cleave single-stranded DNA and relieve negative supercoils in discrete steps corresponding to the passage of the intact DNA strand through the cleaved strand. Although type IA topoisomerases are assumed to accomplish this strand passage via a protein-mediated DNA gate, opening of this gate has never been observed. We developed a single-molecule assay to directly measure gate opening of the Escherichia coli type IA topoisomerases I and III. We found that after cleavage of single-stranded DNA, the protein gate opens by as much as 6.6 nm and can close against forces in excess of 16 pN. Key differences in the cleavage, ligation, and gate dynamics of these two enzymes provide insights into their different cellular functions. The single-molecule results are broadly consistent with conformational changes obtained from molecular dynamics simulations. These results allowed us to develop a mechanistic model of interactions between type IA topoisomerases and single-stranded DNA

Efficacy and safety of two unfractionated heparin dosing strategies with tenecteplase in acute myocardial infarction (results from Assessment of the Safety and Efficacy of a New Thrombolytic Regimens 2 and 3).

Item does not contain fulltextWe investigated the effect of smaller dose, weight-adjusted heparin with earlier monitoring of activated partial thromboplastin time on the incidence of ischemic and hemorrhagic complications in patients with ST-elevation myocardial infarction treated with full-dose tenecteplase. We compared the outcomes of patients enrolled in the Second Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT-2; n = 8,461) who received heparin stratified by weight (patients weighing >67 kg received a 5,000-U bolus plus infusion at 1,000 U/hour; those weighing < or =67 kg received a 4,000-U bolus plus infusion at 800 U/hour) with patients in ASSENT-3 who received weight-adjusted heparin (60-U/kg bolus, maximum 4,000 U/hour, followed by a 12-U/kg/hour infusion, maximum 1,000 U/hour). Compared with patients in ASSENT-2, those in ASSENT-3 had similar rates of 30-day mortality, recurrent infarction, and intracranial hemorrhage, less major bleeding (2.2% vs 4.7%, p <0.001), and less refractory ischemia (6.5% vs 8.6%, p <0.001). After adjustment for baseline characteristics, patients in ASSENT-3 had similar rates of 30-day mortality (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.77 to 1.19) and intracranial hemorrhage (OR 1.02, 95% CI 0.61 to 1.69) but less major bleeding (OR 0.49, 95% CI 0.35 to 0.67) than did patients in ASSENT-2. These findings support the use of smaller dose, weight-adjusted heparin in patients with ST-elevation myocardial infarction treated with tenecteplase