Nickel manganite (NiMn2O4) samples synthesized by a vapor–solid method at temperatures in the range of 1000–1400 °C are studied in this work. The stability and properties of this ternary compound ...together with the presence of NiO in the form of p–n heterostructures have been analyzed by means of diverse electron microscopy and spectroscopy techniques. The formation of the ternary compound with improved crystallinity is promoted as the temperature of the synthesis is increased. Moreover, the samples synthesized at higher temperatures exhibit the growth of microcrystals with micro- and nanoislands on top of their lateral surfaces, leading to patterned surfaces with variable Ni and Mn composition. The combination of Raman spectroscopy, including wavenumber-filtered images, and electron backscattered diffraction confirms that most of these micro- and nanoislands consist of NiMn2O4 grown on top of NiO surfaces. X-Ray photoelectron spectroscopy and microscopy at synchrotron facilities confirm the presence of nickel manganite nanoislands covering the surface of NiO surfaces. Aspects such as the growth mechanisms, nickel manganite vibrational modes, and inversion factor of NiMn2O4 have been discussed in this work.
Nonlinear nanophotonics leverages engineered nanostructures to funnel light into small volumes and intensify nonlinear optical processes with spectral and spatial control. Owing to its intrinsically ...large and electrically tunable nonlinear optical response, graphene is an especially promising nanomaterial for nonlinear optoelectronic applications. Here we report on exceptionally strong optical nonlinearities in graphene-insulator-metal heterostructures, which demonstrate an enhancement by three orders of magnitude in the third-harmonic signal compared with that of bare graphene. Furthermore, by increasing the graphene Fermi energy through an external gate voltage, we find that graphene plasmons mediate the optical nonlinearity and modify the third-harmonic signal. Our findings show that graphene-insulator-metal is a promising heterostructure for optically controlled and electrically tunable nano-optoelectronic components.
Due to the two-dimensional character of graphene, the plasmons sustained by this material have been invariably studied in supported samples so far. The substrate provides stability for graphene but ...often causes undesired interactions (such as dielectric losses, phonon hybridization, and impurity scattering) that compromise the quality and limit the intrinsic flexibility of graphene plasmons. Here, we demonstrate the visualization of plasmons in suspended graphene at room temperature, exhibiting high-quality factor Q~33 and long propagation length > 3 μm. We introduce the graphene suspension height as an effective plasmonic tuning knob that enables in situ change of the dielectric environment and substantially modulates the plasmon wavelength, propagation length, and group velocity. Such active control of micrometer plasmon propagation facilitates near-unity-order modulation of nanoscale energy flow that serves as a plasmonic switch with an on-off ratio above 14. The suspended graphene plasmons possess long propagation length, high tunability, and controllable energy transmission simultaneously, opening up broad horizons for application in nano-photonic devices.
Interstellar extinction toward the Galactic Center (GC) is large and significantly differential. Its reddening and dimming effects in red clump (RC) stars in the Galactic Bulge can be exploited to ...better constrain the extinction law toward the innermost Galaxy. By virtue of a deep and complete catalog of more than 30 million objects at and obtained from VVV survey observations, we apply the RC method to infer the selective-to-total extinction ratios in the Z, Y, J, H, and Ks broadband near-infrared filters. The measured values are smaller than previously reported, and are not constant, with mean values of, e.g., and . We also obtain a ratio AZ:AY:AJ:AH: of 7.74:5.38:3.30:1.88:1.0, implying extinction toward the GC to follow a distribution as a function of wavelength steeper than previously reported, consistent with a power law in the near-infrared.
Aim
To evaluate the impact of a psychoeducational, mobile health intervention based on cognitive behavioural therapy and mindfulness‐based approaches on the mental health of healthcare workers at the ...frontline against COVID‐19 in Spain.
Design
We will carry out a two‐week, individually randomized, parallel group, controlled trial. Participants will be individually randomized to receive the PsyCovidApp intervention or control App intervention.
Methods
The PsyCovidApp intervention will include five modules: emotional skills, lifestyle behaviour, work stress and burnout, social support, and practical tools. Healthcare workers having attended patients with COVID‐19 will be randomized to receive the PsyCovidApp intervention (intervention group) or a control App intervention (control group). A total of 440 healthcare workers will be necessary to assure statistical power. Measures will be collected telephonically by a team of psychologists at baseline and immediately after the 2 weeks intervention period. Measures will include stress, depression and anxiety (DASS‐21 questionnaire—primary endpoint), insomnia (ISI), burnout (MBI‐HSS), post‐traumatic stress disorder (DTS), and self‐efficacy (GSE). The study was funded in May 2020, and was ethically approved in June 2020. Trial participants, outcome assessors and data analysts will be blinded to group allocation.
Discussion
Despite the increasing use of mobile health interventions to deliver mental health care, this area of research is still on its infancy. This study will help increase the scientific evidence about the effectiveness of this type of intervention on this specific population and context.
Impact
Despite the lack of solid evidence about their effectiveness, mobile‐based health interventions are already being widely implemented because of their low cost and high scalability. The findings from this study will help health services and organizations to make informed decisions in relation to the development and implementation of this type of interventions, allowing them pondering not only their attractive implementability features, but also empirical data about its benefits.
Clinical trial registration
NCT04393818 (ClinicalTrials.gov identifier).
Approved funding
May 2020.
ABSTRACT
Red clump stars are commonly used to map the reddening and morphology of the inner regions of the Milky Way. We use the new photometric catalogues of the VISTA Variables in the Vía Láctea ...survey to achieve twice the spatial resolution of previous reddening maps for Galactic longitudes $\rm -10^{\circ }\lt l\lt 10^{\circ }$ and latitudes $\rm -1.5^{\circ }\lt b\lt 1.5^{\circ }$. We use these de-reddened catalogues to construct the $\rm K_{s}$ luminosity function around the red clump in the Galactic plane. We show that the secondary peak (fainter than the red clump) detected in these regions does not correspond to the bulge red-giant branch bump alone, as previously interpreted. Instead, this fainter clump corresponds largely to the over-density of red clump stars tracing the spiral arm structure behind the Galactic bar. This result suggests that studies aiming to characterize the bulge red-giant branch bump should avoid low galactic latitudes ($\rm |b|\lt 2^{\circ }$), where the background red clump population contributes significant contamination. It furthermore highlights the need to include this structural component in future modelling of the Galactic bar.
The consumption of carotenoids has beneficial effects on health, reducing the risk of certain forms of cancer, cardiovascular diseases, and macular degeneration, among others. The mechanism of action ...of carotenoids has not been clearly identified; however, it has been associated with the antioxidant capacity of carotenoids, which acts against reactive oxygen species and inactivating free radicals, although it has also been shown that carotenoids modulate gene expression. Dietary carotenoids are absorbed and accumulated in the liver and other organs, where they exert their beneficial effects. In recent years, it has been described that the intake of carotenoids can significantly reduce the risk of suffering from liver diseases, such as non-alcoholic fatty liver disease (NAFLD). This disease is characterized by an imbalance in lipid metabolism producing the accumulation of fat in the hepatocyte, leading to lipoperoxidation, followed by oxidative stress and inflammation. In the first phases, the main treatment of NAFLD is to change the lifestyle, including dietary habits. In this sense, carotenoids have been shown to have a hepatoprotective effect due to their ability to reduce oxidative stress and regulate the lipid metabolism of hepatocytes by modulating certain genes. The objective of this review was to provide a description of the effects of dietary carotenoids from fruits and vegetables on liver health.
The mitochondrial calcium uniporter complex is essential for calcium (Ca2+) uptake into mitochondria of all mammalian tissues, where it regulates bioenergetics, cell death, and Ca2+ signal ...transduction. Despite its involvement in several human diseases, we currently lack pharmacological agents for targeting uniporter activity. Here we introduce a high-throughput assay that selects for human MCU-specific small-molecule modulators in primary drug screens. Using isolated yeast mitochondria, reconstituted with human MCU, its essential regulator EMRE, and aequorin, and exploiting a D-lactate- and mannitol/sucrose-based bioenergetic shunt that greatly minimizes false-positive hits, we identify mitoxantrone out of more than 600 clinically approved drugs as a direct selective inhibitor of human MCU. We validate mitoxantrone in orthogonal mammalian cell-based assays, demonstrating that our screening approach is an effective and robust tool for MCU-specific drug discovery and, more generally, for the identification of compounds that target mitochondrial functions.
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•Targeting human MCU in yeast mitochondria is an effective drug discovery strategy•A yeast-specific bioenergetic shunt minimizes detection of false-positive hits•An orthogonal, interspecies drug screening can identify specific MCU modulators•Mitoxantrone is a selective and direct inhibitor of MCU
Arduino et al. develop a high-throughput drug discovery strategy to identify chemical modulators of the mitochondrial calcium uniporter. They find that mitoxantrone is a selective and direct inhibitor of the MCU channel.
Aims. The windows of low extinction in the Milky Way (MW) plane are rare but important because they enable us to place structural constraints on the opposite side of the Galaxy, which has hither to ...been done rarely. Methods. We use the near-infrared (near-IR) images of the VISTA Variables in the Vía Láctea (VVV) Survey to build extinction maps and to identify low extinction windows towards the Southern Galactic plane. Here we report the discovery of VVV WIN 1713−3939, a very interesting window with relatively uniform and low extinction conveniently placed very close to the Galactic plane. Results. The new window of roughly 30 arcmin diameter is located at Galactic coordinates (l, b) = (347.4, −0.4) deg. We analyse the VVV near-IR colour-magnitude diagrams in this window. The mean total near-IR extinction and reddening values measured for this window are AKs = 0.46 and E(J − Ks) = 0.95. The red clump giants within the window show a bimodal magnitude distribution in the Ks band, with peaks at Ks = 14.1 and 14.8 mag, corresponding to mean distances of D = 11.0 ± 2.4 and 14.8 ± 3.6 kpc, respectively. We discuss the origin of these red clump overdensities within the context of the MW disk structure.
The ability to manipulate optical fields and the energy flow of light is central to modern information and communication technologies, as well as quantum information processing schemes. However, ...because photons do not possess charge, a way of controlling them efficiently by electrical means has so far proved elusive. A promising way to achieve electric control of light could be through plasmon polaritons—coupled excitations of photons and charge carriers—in graphene. In this two-dimensional sheet of carbon atoms, it is expected that plasmon polaritons and their associated optical fields can readily be tuned electrically by varying the graphene carrier density. Although evidence of optical graphene plasmon resonances has recently been obtained spectroscopically, no experiments so far have directly resolved propagating plasmons in real space. Here we launch and detect propagating optical plasmons in tapered graphene nanostructures using near-field scattering microscopy with infrared excitation light. We provide real-space images of plasmon fields, and find that the extracted plasmon wavelength is very short—more than 40 times smaller than the wavelength of illumination. We exploit this strong optical field confinement to turn a graphene nanostructure into a tunable resonant plasmonic cavity with extremely small mode volume. The cavity resonance is controlled in situ by gating the graphene, and in particular, complete switching on and off of the plasmon modes is demonstrated, thus paving the way towards graphene-based optical transistors. This successful alliance between nanoelectronics and nano-optics enables the development of active subwavelength-scale optics and a plethora of nano-optoelectronic devices and functionalities, such as tunable metamaterials, nanoscale optical processing, and strongly enhanced light–matter interactions for quantum devices and biosensing applications.
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