1,032 research outputs found
Probing the Role of the Barrier Layer in Magnetic Tunnel Junction Transport
Magnetic tunnel junctions with a ferrimagnetic barrier layer have been
studied to understand the role of the barrier layer in the tunneling process -
a factor that has been largely overlooked until recently. Epitaxial oxide
junctions of highly spin polarized La0.7Sr0.3MnO3 and Fe3O4 electrodes with
magnetic NiMn2O4 (NMO) insulating barrier layers provide a magnetic tunnel
junction system in which we can probe the effect of the barrier by comparing
junction behavior above and below the Curie temperature of the barrier layer.
When the barrier is paramagnetic, the spin polarized transport is dominated by
interface scattering and surface spin waves; however, when the barrier is
ferrimagnetic, spin flip scattering due to spin waves within the NMO barrier
dominates the transport.Comment: 10 pages, 3 figure
Does Charter School Attendance Improve Test Scores?: Comments and Reactions on the Arizona Achievement Study
Gender Justice In The Americas: A Transnational Dialogue On Sexuality, Violence, Reproduction, And Human Rights
Gender Justice In The Americas: A Transnational Dialogue On Sexuality, Violence, Reproduction, And Human Rights
Long-Chain ω-3 Levels Are Associated With Increased Alcohol Sensitivity in a Population-Based Sample of Adolescents
Genuine DNA/polyethylenimine (PEI) Complexes Improve Transfection Properties and Cell Survival
Polyethylenimine (PEI) has been described as one of the most efficient cationic polymers for in vitro gene delivery. Systemic delivery of PEI/DNA polyplexes leads to a lung-expression tropism. Selective in vivo gene transfer would require targeting and stealth particles. Here, we describe two strategies for chemically coupling polyethylene glycol (PEG) to PEI, to form protected ligand-bearing particles. Pre-grafted PEG–PEI polymers lost their DNA condensing property, hence their poor performances. Coupling PEG to pre-formed PEI/DNA particles led to the expected physical properties. However, low transfection efficacies raised the question of the fate of excess free polymer in solution. We have developed a straightforward a purification assay, which uses centrifugation-based ultrafiltration. Crude polyplexes were purified, with up to 60% of the initial PEI dose being removed. The resulting purified and unshielded PEI/DNA polyplexes are more efficient for transfection and less toxic to cells in culture than the crude ones. Moreover, the in vivo toxicity of the polyplexes was greatly reduced, without affecting their efficacy
Stone-Wales Transformation Paths in Fullerene C60
The mechanisms of formation of a metastable defect isomer of fullerene C60
due to the Stone-Wales transformation are theoretically studied. It is
demonstrated that the paths of the "dynamic" Stone-Wales transformation at a
high sufficient for overcoming potential barriers) temperature can differ from
the two "adiabatic" transformation paths discussed in the literature. This
behavior is due to the presence of a great near-flat segment of the
potential-energy surface in the neighborhood of metastable states. Besides, the
sequence of rupture and formation of interatomic bonds is other than that in
the case of the adiabatictransformation.Comment: 10 pages, 6 figure
Transcriptional analysis of the response of \u3ci\u3eC. elegans\u3c/i\u3e to ethanol exposure
Ethanol-induced transcriptional changes underlie important physiological responses to ethanol that are likely to contribute to the addictive properties of the drug. We examined the transcriptional responses of Caenorhabditis elegans across a timecourse of ethanol exposure, between 30 min and 8 h, to determine what genes and genetic pathways are regulated in response to ethanol in this model. We found that short exposures to ethanol (up to 2 h) induced expression of metabolic enzymes involved in metabolizing ethanol and retinol, while longer exposure (8 h) had much more profound effects on the transcriptome. Several genes that are known to be involved in the physiological response to ethanol, including direct ethanol targets, were regulated at 8 h of exposure. This longer exposure to ethanol also resulted in the regulation of genes involved in cilia function, which is consistent with an important role for the effects of ethanol on cilia in the deleterious effects of chronic ethanol consumption in humans. Finally, we found that food deprivation for an 8-h period induced gene expression changes that were somewhat ameliorated by the presence of ethanol, supporting previous observations that worms can use ethanol as a calorie source
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Comparative Study of Prepectoral and Subpectoral Expander-Based Breast Reconstruction and Clavien IIIb Score Outcomes
Background: Prepectoral breast reconstruction is increasingly popular. This study compares complications between 2 subpectoral and 1 prepectoral breast reconstruction technique. Methods: Between 2008 and 2015, 294 two-staged expander breast reconstructions in 213 patients were performed with 1 of 3 surgical techniques: (1) Prepectoral, (2) subpectoral with acellular dermal matrix (ADM) sling (“Classic”), or (3) subpectoral/subserratus expander placement without ADM (“No ADM”). Demographics, comorbidities, radiation therapy, and chemotherapy were assessed for correlation with Clavien IIIb score outcomes. Follow-up was a minimum of 6 months. Results: Surgical cohorts (n = 165 Prepectoral; n = 77 Classic; n = 52 No ADM) had comparable demographics except Classic had more cardiac disease (P = 0.03), No ADM had higher body mass index (BMI) (P = 0.01), and the Prepectoral group had more nipple-sparing mastectomies (P 40, stage 4 cancer, and contralateral prophylactic mastectomy were associated with adverse expander outcomes and a prior history of radiation therapy adversely impacted implant outcomes. Ninety-day follow-up for expander and implant complications may be a better National Surgical Quality Improvement Program measure
Magnetism of NiMn2O4-Fe3O4 spinel interfaces
We investigate the magnetic properties of the isostructural spinel-spinel interface of NiMn{sub 2}O{sub 4}(NMO)-Fe{sub 3}O{sub 4}. Although the magnetic transition temperature of the NMO film is preserved, both bulk and interface sensitive measurements demonstrate that the interface exhibits strong interfacial magnetic coupling up to room temperature. While NMO thin films have a ferrimagnetic transition temperature of 60 K, both NiFe{sub 2}O{sub 4} and MnFe{sub 2}O{sub 4} are ferrimagnetic at room temperature. Our experimental results suggest that these magnetic properties arise from a thin interdiffused region of (Fe,Mn,Ni){sub 3}O{sub 4} at the interface, leading to Mn and Ni magnetic properties similar to those of MnFe{sub 2}O{sub 4} and NiFe{sub 2}O{sub 4}
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