1,524 research outputs found
Selective interlayer ferromagnetic coupling between the Cu spins in YBa Cu O grown on top of La Ca MnO
Studies to date on ferromagnet/d-wave superconductor heterostructures focus
mainly on the effects at or near the interfaces while the response of bulk
properties to heterostructuring is overlooked. Here we use resonant soft x-ray
scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between
the in-plane Cu spins in YBa Cu O (YBCO) superconductor when it
is grown on top of ferromagnetic La Ca MnO (LCMO) manganite
layer. This coupling, present in both normal and superconducting states of
YBCO, is sensitive to the interfacial termination such that it is only observed
in bilayers with MnO_2but not with La Ca interfacial
termination. Such contrasting behaviors, we propose, are due to distinct
energetic of CuO chain and CuO plane at the La Ca and
MnO terminated interfaces respectively, therefore influencing the transfer
of spin-polarized electrons from manganite to cuprate differently. Our findings
suggest that the superconducting/ferromagnetic bilayers with proper interfacial
engineering can be good candidates for searching the theorized
Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the
competing quantum orders in highly correlated electron systems.Comment: Please note the change of the title. Text might be slightly different
from the published versio
Substantivity of Carbodiimide Inhibition on Dentinal Enzyme Activity over Time
The use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide HCl (EDC) has recently been investigated for its effectiveness in the prevention of collagen degradation over time and the improvement of resin-dentin bond durability. The objective of the present study was to evaluate the effects of a 0.3 M EDC-containing conditioner on endogenous enzymatic activities within the hybrid layer (HL) created by a self-etch or an etch-and-rinse adhesive after 1 y. The activity within the HL was examined using in situ zymography and confocal laser scanning microscopy after 24 h or 1-y storage in artificial saliva. Dentin specimens were bonded with Clearfil SE Bond (CSE) or XP Bond (XPB). For CSE, the self-etching primer was applied and treated with 0.3 M EDC for 1 min, and then the bonding agent was applied. For XPB, dentin was etched and treated with 0.3 M EDC for 1 min and then bonded with the primer-bonding agent. Control specimens were prepared without EDC treatment. Slices containing the adhesive-dentin interface were covered with fluorescein-conjugated gelatin and observed with a multiphoton confocal microscope. Fluorescence intensity emitted by hydrolyzed fluorescein-conjugated gelatin was quantified, and the amount of gelatinolytic activity was represented by the percentage of green fluorescence emitted within the HL. After 24 h of storage, enzymatic activity was detected by in situ zymography within the HLs of both tested adhesives, with XPB higher than CSE (P <0.05). Almost no fluorescence signal was detected when specimens were pretreated with EDC compared to controls (P <0.05). After 1 y of storage, enzymatic activities significantly increased for all groups (excluding XPB control) compared to 24-h storage (P <0.05), with EDC pretreated specimens exhibiting significantly lower activity than controls (P <0.05). The present study showed, for the first time, that the use of EDC for both the self-etch and the etch-and-rinse approaches results in the reduction but not complete inhibition of matrix-bound collagenolytic enzyme activities over time in the HL.Peer reviewe
Effect of benzalkonium chloride on dentin bond strength and endogenous enzymatic activity
Objective: This in vitro study evaluated at baseline (T0) and over time (T12 months), the effect of a multi-mode universal adhesive compared with two experimental formulations blended with different concentrations of benzalkonium chloride (BAC), on bond strength and endogenous enzymatic activity. Methods and materials: Specimens were assigned to the following groups according to the adhesive protocol: G1) All-Bond Universal (ABU) self-etch (SE); G2) ABU + 0.5% BAC SE; G3) ABU + 1% methacrylate BAC SE; G4) ABU etch-and-rinse (E&R); G5) ABU + 0.5% BAC E&R; G6) ABU + 1% methacrylate BAC E&R. Gelatin zymography was performed on dentin powder obtained from eight human third molars. Endogenous enzymatic activity within the hybrid layer was examined using in situ zymography after 24 h (T0) or 1-year storage in artificial saliva (T12). Forty intact molars were prepared for microtensile bond strength test at T0 and T12. Results were statistically analyzed with three-way ANOVA (\u3b1 = 0.05). Results: Gelatin zymography assay and in situ zymography quantification analyses indicated that all the BAC-containing formulations decreased matrix metalloproteinase expression. However, in situ zymography showed a general trend of enzymatic activity increase after aging. Microtensile bond-strength testing showed decrease in bond strength over time in all the tested groups; performances of the 1% methacrylate BAC experimental groups were worse than the control. Conclusions: BAC-containing adhesives reduce endogenous enzymatic activity both immediately and over time. However, independently from the adhesive employed, increase in the gelatinolytic activity over time and decrease in bond strength was found (especially in the BAC + 1% methacrylate groups), probably due to impaired polymerization properties. Clinical significance: Adhesives containing protease inhibitors are practical and efficient tools in clinical practice for enhancement of the longevity of dental restorations. However, extensive investigation of the mechanical and adhesive properties of the material is necessary prior to their clinical use
Dynamics of Fluid Vesicles in Oscillatory Shear Flow
The dynamics of fluid vesicles in oscillatory shear flow was studied using
differential equations of two variables: the Taylor deformation parameter and
inclination angle . In a steady shear flow with a low viscosity
of internal fluid, the vesicles exhibit steady tank-treading
motion with a constant inclination angle . In the oscillatory flow
with a low shear frequency, oscillates between or
around for zero or finite mean shear rate ,
respectively. As shear frequency increases, the vesicle
oscillation becomes delayed with respect to the shear oscillation, and the
oscillation amplitude decreases. At high with , another limit-cycle oscillation between and
is found to appear. In the steady flow, periodically rotates
(tumbling) at high , and and the vesicle shape
oscillate (swinging) at middle and high shear rate. In the
oscillatory flow, the coexistence of two or more limit-cycle oscillations can
occur for low in these phases. For the vesicle with a fixed shape,
the angle rotates back to the original position after an oscillation
period. However, it is found that a preferred angle can be induced by small
thermal fluctuations.Comment: 11 pages, 13 figure
Microglia in brain development and regeneration
It has recently emerged that microglia, the tissue-resident macrophages of the central nervous system, play significant non-innate immune roles to support the development, maintenance, homeostasis and repair of the brain. Apart from being highly specialized brain phagocytes, microglia modulate the development and functions of neurons and glial cells through both direct and indirect interactions. Thus, recognizing the elements that influence the homeostasis and heterogeneity of microglia in normal brain development is crucial to understanding the mechanisms that lead to early disease pathogenesis of neurodevelopmental disorders. In this Review, we discuss recent studies that have elucidated the physiological development of microglia and summarize our knowledge of their non-innate immune functions in brain development and tissue repair.T32 CA009302 - NCI NIH HHShttps://doi.org/10.1242/dev.200425Accepted manuscriptPublished versio
Frailty predicts mortality in all emergency surgical admissions regardless of age : An observational study
Acknowledgements: Cardiff and Vale University Health Board: Aimee Browning, Svetlana Kulikouskaya, Rebecca Best, Andrew Forrester, Joseph Ereaut, James Moore, Dominic Hampson, Stephanie Owen, Shaanjan Islam, Nicolas Gill, Stephan Merrix, Jack Topham, Pip Killingworth, Syed Rahman and Nurulaida Mohd Darus. North Bristol NHS Trust: Emily Benson, Tom Wright, Sarah Blake, Calum Honeyman, Simon Huf, Anni Dong, Indira Garaeva, Manuk Wijeyaratne, Michael Campbell and Eng Hean Teh. Royal Alexandra Hospital: Adam Tay and Nurwasimah Haj Asnan. NHS Grampian: Matthew Greig, Vincent Quan. Central Manchester University Hospitals: Elizabeth Norr. Declaration of Conflict of Interest None. Declaration of Sources of Funding: We acknowledge the support of the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London (B.C.).Peer reviewedPostprintPostprin
Quantum Magnetization Plateau in Spin-1 Triangular-Lattice Antiferromagnet BaNiSbO
We report the results of magnetization and specific heat measurements on
BaNiSbO, which is a quasi-two-dimensional spin-1 triangular-lattice
antiferromagnet. We observed a nonclassical magnetization plateau at one-third
of the saturation magnetization that is driven by spin frustration and quantum
fluctuation. Exact diagonalization for a 21-site rhombic cluster was performed
to analyze the magnetization process. Experimental and calculated results agree
well.Comment: published in Journal of the Physical Society of Japan 80 (2011)
09370
Adaptive Introgression across Semipermeable Species Boundaries between Local Helicoverpa zea and Invasive Helicoverpa armigera Moths.
Hybridization between invasive and native species has raised global concern, given the dramatic increase in species range shifts and pest outbreaks due to anthropogenic dispersal. Nevertheless, secondary contact between sister lineages of local and invasive species provides a natural laboratory to understand the factors that determine introgression and the maintenance or loss of species barriers. Here, we characterize the early evolutionary outcomes following secondary contact between invasive Helicoverpa armigera and native H. zea in Brazil. We carried out whole-genome resequencing of Helicoverpa moths from Brazil in two temporal samples: during the outbreak of H. armigera in 2013 and 2017. There is evidence for a burst of hybridization and widespread introgression from local H. zea into invasive H. armigera coinciding with H. armigera expansion in 2013. However, in H. armigera, the admixture proportion and the length of introgressed blocks were significantly reduced between 2013 and 2017, suggesting selection against admixture. In contrast to the genome-wide pattern, there was striking evidence for adaptive introgression of a single region from the invasive H. armigera into local H. zea, including an insecticide resistance allele that increased in frequency over time. In summary, despite extensive gene flow after secondary contact, the species boundaries are largely maintained except for the single introgressed region containing the insecticide-resistant locus. We document the worst-case scenario for an invasive species, in which there are now two pest species instead of one, and the native species has acquired resistance to pyrethroid insecticides through introgression
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