1,832 research outputs found
Enhanced thermal stability and fracture toughness of TiAlN coatings by Cr, Nb and V-alloying
The effect of metal alloying on mechanical properties including hardness and fracture toughness were investigated in three alloys, Ti~0.33Al0.50(Me)~0.17N (Me¿=¿Cr, Nb and V), and compared to Ti0.50Al0.50N, in the as-deposited state and after annealing. All studied alloys display similar as-deposited hardness while the hardness evolution during annealing is found to be connected to phase transformations, related to the alloy's thermal stability. The most pronounced hardening was observed in Ti0.50Al0.50N, while all the coatings with additional metal elements sustain their hardness better and they are harder than Ti0.50Al0.50N after annealing at 1100¿°C. Fracture toughness properties were extracted from scratch tests. In all tested conditions, as-deposited and annealed at 900 and 1100¿°C, Ti0.33Al0.50Nb0.17N show the least surface and sub-surface damage when scratched despite the differences in decomposition behavior and h-AlN formation. Theoretically estimated ductility of phases existing in the coatings correlates well with their crack resistance. In summary, Ti0.33Al0.50Nb0.17N is the toughest alloy in both as-deposited and post-annealed states.Peer ReviewedPostprint (author's final draft
Gravitational perturbations from NHEK to Kerr
We revisit the spectrum of linear axisymmetric gravitational perturbations of
the (near-)extreme Kerr black hole. Our aim is to characterise those
perturbations that are responsible for the deviations away from extremality,
and to contrast them with the linearized perturbations treated in the
Newman-Penrose formalism. For the near horizon region of the (near-)extreme
Kerr solution, i.e. the (near-)NHEK background, we provide a complete
characterisation of axisymmetric modes. This involves an infinite tower of
propagating modes together with the much subtler low-lying mode sectors that
contain the deformations driving the black hole away from extremality. Our
analysis includes their effects on the line element, their contributions to
Iyer-Wald charges around the NHEK geometry, and how to reconstitute them as
gravitational perturbations on Kerr. We present in detail how regularity
conditions along the angular variables modify the dynamical properties of the
low-lying sector, and in particular their role in the new developments of
nearly-AdS holography.Comment: 73 pages, 1 figure; v2: minor typos corrected; v3: matches published
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The Role of Surface and Underlying Forms When Processing Tonal Alternations in Mandarin Chinese: A Mismatch Negativity Study
This work is licensed under a Creative Commons Attribution 4.0 International License.Phonological alternation (sound change depending on the phonological environment) poses challenges to spoken word recognition models. Mandarin Chinese T3 sandhi is such a phenomenon in which a tone 3 (T3) changes into a tone 2 (T2) when followed by another T3. In a mismatch negativity (MMN) study examining Mandarin Chinese T3 sandhi, participants passively listened to either a T2 word [tʂu2 je4] /tʂu2 je4/, a T3 word [tʂu3 je4] /tʂu3 je4/, a sandhi word [tʂu2 jen3] /tʂu3 jen3/, or a mix of T3 and sandhi word standards. The deviant in each condition was a T2 word [tʂu2]. Results showed an MMN only in the T2 and T3 conditions but not in the Sandhi or Mix conditions. All conditions also yielded omission MMNs. This pattern cannot be explained based on the surface forms of standards and deviants; rather these data suggest an underspecified or underlying T3 stored linguistic representation used in spoken word processing
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Role for polo-like kinase 4 in mediation of cytokinesis.
The mitotic protein polo-like kinase 4 (PLK4) plays a critical role in centrosome duplication for cell division. By using immunofluorescence, we confirm that PLK4 is localized to centrosomes. In addition, we find that phospho-PLK4 (pPLK4) is cleaved and distributed to kinetochores (metaphase and anaphase), spindle midzone/cleavage furrow (anaphase and telophase), and midbody (cytokinesis) during cell division in immortalized epithelial cells as well as breast, ovarian, and colorectal cancer cells. The distribution of pPLK4 midzone/cleavage furrow and midbody positions pPLK4 to play a functional role in cytokinesis. Indeed, we found that inhibition of PLK4 kinase activity with a small-molecule inhibitor, CFI-400945, prevents translocation to the spindle midzone/cleavage furrow and prevents cellular abscission, leading to the generation of cells with polyploidy, increased numbers of duplicated centrosomes, and vulnerability to anaphase or mitotic catastrophe. The regulatory role of PLK4 in cytokinesis makes it a potential target for therapeutic intervention in appropriately selected cancers
Investment in HIV/AIDS programs: Does it help strengthen health systems in developing countries?
<p>Abstract</p> <p>Background</p> <p>There is increasing debate about whether the scaled-up investment in HIV/AIDS programs is strengthening or weakening the fragile health systems of many developing countries. This article examines and assesses the evidence and proposes ways forward.</p> <p>Discussion</p> <p>Considerably increased resources have been brought into countries for HIV/AIDS programs by major Global Health Initiatives. Among the positive impacts are the increased awareness of and priority given to public health by governments. In addition, services to people living with HIV/AIDS have rapidly expanded. In many countries infrastructure and laboratories have been strengthened, and in some, primary health care services have been improved. The effect of AIDS on the health work force has been lessened by the provision of antiretroviral treatment to HIV-infected health care workers, by training, and, to an extent, by task-shifting. However, there are reports of concerns, too – among them, a temporal association between increasing AIDS funding and stagnant reproductive health funding, and accusations that scarce personnel are siphoned off from other health care services by offers of better-paying jobs in HIV/AIDS programs. Unfortunately, there is limited hard evidence of these health system impacts.</p> <p>Because service delivery for AIDS has not yet reached a level that could conceivably be considered "as close to Universal Access as possible," countries and development partners must maintain the momentum of investment in HIV/AIDS programs. At the same time, it should be recognized that global action for health is even more underfunded than is the response to the HIV epidemic. The real issue is therefore not whether to fund AIDS or health systems, but how to increase funding for both.</p> <p>Summary</p> <p>The evidence is mixed – mostly positive but some negative – as to the impact on health systems of the scaled-up responses to HIV/AIDS driven primarily by global health partnerships. Current scaled-up responses to HIV/AIDS must be maintained and strengthened. Instead of endless debate about the comparative advantages of vertical and horizontal approaches, partners should focus on the best ways for investments in response to HIV to also broadly strengthen the primary health care systems.</p
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Investment in HIV/AIDS programs: Does it help strengthen health systems in developing countries?
Background: There is increasing debate about whether the scaled-up investment in HIV/AIDS programs is strengthening or weakening the fragile health systems of many developing countries. This article examines and assesses the evidence and proposes ways forward. Discussion: Considerably increased resources have been brought into countries for HIV/AIDS programs by major Global Health Initiatives. Among the positive impacts are the increased awareness of and priority given to public health by governments. In addition, services to people living with HIV/AIDS have rapidly expanded. In many countries infrastructure and laboratories have been strengthened, and in some, primary health care services have been improved. The effect of AIDS on the health work force has been lessened by the provision of antiretroviral treatment to HIV-infected health care workers, by training, and, to an extent, by task-shifting. However, there are reports of concerns, too – among them, a temporal association between increasing AIDS funding and stagnant reproductive health funding, and accusations that scarce personnel are siphoned off from other health care services by offers of better-paying jobs in HIV/AIDS programs. Unfortunately, there is limited hard evidence of these health system impacts. Because service delivery for AIDS has not yet reached a level that could conceivably be considered "as close to Universal Access as possible," countries and development partners must maintain the momentum of investment in HIV/AIDS programs. At the same time, it should be recognized that global action for health is even more underfunded than is the response to the HIV epidemic. The real issue is therefore not whether to fund AIDS or health systems, but how to increase funding for both. Summary: The evidence is mixed – mostly positive but some negative – as to the impact on health systems of the scaled-up responses to HIV/AIDS driven primarily by global health partnerships. Current scaled-up responses to HIV/AIDS must be maintained and strengthened. Instead of endless debate about the comparative advantages of vertical and horizontal approaches, partners should focus on the best ways for investments in response to HIV to also broadly strengthen the primary health care systems
Mn3O4@CoMn2O4-CoxOy nanoparticles : partial cation exchange synthesis and electrocatalytic properties toward the oxygen reduction and evolution reactions
Mn3O4@CoMn2O4 nanoparticles (NPs) were produced at low temperature and ambient atmosphere using a one -pot two-step synthesis protocol involving the cation exchange of Mn by Co in preformed Mn3O4 NPs. Selecting the proper cobalt precursor, the nucleation of CoxOy crystallites at the Mn3O4@a CoMn2O4 surface could be simultaneously promoted to form Mn3O4@CoMn2O4-CoxOy NPs. Such heterostructured NPs were investigated for oxygen reduction and evolution reactions (ORR, OER) in alkaline solution. Mn3O4@ CoMn2O4-Cox0y NPs with [Co]/[Mn] = 1 showed low overpotentials of 0.31 Vat(-3) mA.cm(-2) and a small Tafel slope of 52 mV.dec(-1) for ORR, and overpotentials of 0.31 V at 10 mAPeer ReviewedPostprint (author's final draft
Toona sinensis
Toona sinensis leaf (TSL) is commonly used as a vegetable and in spice in Asia. In this study, feeding with aqueous extract of TSL (TSL-A) alleviated oxidative stress and recovered the motility and functions of sperm in rats under oxidative stress. Protein expressions in testes identified by proteomic analysis and verified by Western blot demonstrated that TSL-A not only downregulated the level of glutathione transferase mu6 (antioxidant system), heat shock protein 90 kDa-β (protein misfolding repairing system), cofilin 2 (spermatogenesis), and cyclophilin A (apoptosis) but also upregulated crease3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 (steroidogenesis), heat shock glycoprotein 96, and pancreatic trypsin 1 (sperm-oocyte interaction). These results indicate that TSL-A promotes the functions of sperm and testes via regulating multiple testicular proteins in rats under oxidative stress, suggesting that TSL-A is a valuable functional food supplement to improve functions of sperm and testes for males under oxidative stress
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