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CeVO4 Nanozymes Catalyze the Reduction of Dioxygen to Water without Releasing Partially Reduced Oxygen Species
No full textIn this study, we report a remarkably active CeVO4 nanozyme that functionally mimics cytochromec oxidase (CcO), the terminal enzyme in the respiratory electron transport chain, by catalyzing a four-electron reduction of dioxygen to water. The nanozyme catalyzes the reaction by using cytochromec (Cyt c), the biological electron donor for CcO, at physiologically relevant pH. The CcO activity of the CeVO4 nanozymes depends on the relative ratio of surface Ce3+/Ce4+ ions, the presence of V5+ and the surface-Cytc interactions. The complete reduction of oxygen to water takes place without release of any partially reduced oxygen species (PROS) such as superoxide, peroxide and hydroxyl radicals
Investigating fouling at the pore-scale using a microfluidic membrane mimic filtration system
No full textThe work investigates fouling in a microfluidic membrane mimic (MMM) filtration system for foulants such as polystyrene particles and large polymeric molecules. Our MMM device consists of a staggered arrangement of pillars which enables real-time visualization and analysis of pore-scale phenomena. Different fouling scenarios are investigated by conducting constant-pressure experiments. Fouling experiments are performed with three different types of foulants: polystyrene particle solution (colloidal fouling), polyacrylamide polymer solution (organic fouling) and a mixture of these two solutions (combined fouling). Four major categories of microscopic fouling are observed: cake filtration (upstream), pore blocking (inside the pores), colloidal aggregation (downstream) and colloidal streamer fouling (downstream). Our microfluidic experiments show that downstream colloidal aggregation and streamer fouling have a significant effect on overall membrane fouling which were not studied before
Including mode mixing in a higher-multipole model for gravitational waveforms from nonspinning black-hole binaries
No full textAs gravitational-wave (GW) observations of binary black holes are becoming a precision tool for physics and astronomy, several subdominant effects in the GW signals need to be accurately modeled. Previous studies have shown that neglecting subdominant modes in the GW templates causes an unacceptable loss in detection efficiency and large systematic errors in the estimated parameters for binaries with large mass ratios. Our recent work Mehta et al., Phys. Rev. D 96, 124010 (2017)] constructed a phenomenological gravitational waveform family for nonspinning black-hole binaries that includes subdominant spherical harmonic modes (l = 2; m = +/- 1), (l = 3; m = +/- 3), and (l = 4; m = +/- 4) in addition to the dominant quadrupole mode, (l = 2; m = +/- 2). In this article, we construct analytical models for the (l = 3; m = +/- 2) and (l = 4; m = +/- 3) modes and include them in the existing waveform family. Accurate modeling of these modes is complicated by the mixing of multiple spheroidal harmonic modes. We develop a method for accurately modeling the effect of mode mixing, thus producing an analytical waveform family that has faithfulness greater than 99.6%
Influence of Rainfall Over Eastern Arabian Sea on Its Salinity
No full textThe west coast of India and the adjoining eastern Arabian Sea (EAS) is one of the high rainfall zones of Indian summer monsoon. The summer monsoon rainfall in this region is about 1,036km(3), which is comparable to the annual runoff of the Ganga-Brahmaputra river system. We have investigated the impact of EAS rainfall and Bay of Bengal (BoB) low-salinity water on the Arabian Sea salinity with a suite of experiments using an ocean general circulation model. The sea surface salinity (SSS) of EAS decreases progressively from June to September by 0.5 to 1psu. A numerical experiment that isolates the effect of EAS rainfall suggests that this SSS decrease is largely due to local rainfall over the EAS. The spatial pattern of SSS decrease, however, is influenced by the prevailing West India Coastal Current. The role of low-salinity water originating in the BoB on reducing the EAS salinity has also been examined. In the South Eastern Arabian Sea, during winter, the SSS decreases by about 1.5psu. This freshening is caused by rainfall during the early winter in the southwestern BoB between 6 degrees N and 15 degrees N. Neither rainfall to the north of 15 degrees N nor river runoff into the BoB contributes much to the South Eastern Arabian Sea freshening during winter
Nanophotonic on-chip hybrid plasmonic electro-optic modulator with phase change materials
No full textA vertical hybrid plasmonic waveguide (HPWG) modulator incorporating Au nano-rings and operating in the near-infrared (NIR) band is proposed using phase change chalcogenide thin film (Ge2Sb2Te5, commonly known as GST). It is shown that with amorphous to crystalline phase transition of GST, significant modulation depths can be achieved in the optical C-band. Further, localized surface plasmon resonance (LSPR) excitations from the Au nano-ring embedded in the low-indexed slot region is used to enhance the overall performance of the reported GST based electro-optic modulator. In addition, significant wavelength shifts, and improved extinction ratio (ER) is obtained by varying Au nano-ring radius and other geometrical parameters. Our finite element method based 3D-COMSOL numerical simulations reveal that 12.24 dB/mu m (9.3 dB/mu m) extinction ratio per unit length can be achieved with (without) Au nano-rings considering r=80 nm; L=500 nm; and lambda=1.56 um, respectively
Dissociable sensitivity and bias mechanisms mediate behavioral effects of exogenous attention
No full textAttention can be directed endogenously, based on task-relevant goals, or captured exogenously, by salient stimuli. While recent studies have shown that endogenous attention can facilitate behavior through dissociable sensitivity (sensory) and choice bias (decisional) mechanisms, it is unknown if exogenous attention also operates through dissociable sensitivity and bias mechanisms. We tested human participants on a multialternative change detection task with exogenous attention cues, which preceded or followed change events in close temporal proximity. Analyzing participants' behavior with a multidimensional signal detection model revealed clear dissociations between exogenous cueing effects on sensitivity and bias. While sensitivity was, overall, lower at the cued location compared to other locations, bias was highest at the cued location. With an appropriately designed post-cue control condition, we discovered that the attentional effect of exogenous pre-cueing was to enhance sensitivity proximal to the cue. In contrast, exogenous attention enhanced bias even for distal stimuli in the cued hemifield. Reaction time effects of exogenous cueing could be parsimoniously explained with a diffusion-decision model, in which drift rate was determined by independent contributions from sensitivity and bias at each location. The results suggest a mechanistic schema of how exogenous attention engages dissociable sensitivity and bias mechanisms to shape behavior
Climate Response to Pulse Versus Sustained Stratospheric Aerosol Forcing
No full textSolar geoengineering has been suggested as a potential means to counteract anthropogenic warming. Major volcanic eruptions have been used as natural analogues to large-scale deployments of stratospheric aerosol geoengineering, yet difference in climate responses to these forcings remains unclear. Using the National Center for Atmospheric Research Community Earth System Model, we compare climate responses to two highly idealized stratospheric aerosol forcings that have different durations: a short-term pulse representative of volcanic eruptions and a long-term sustained forcing representative of geoengineering. For the same amount of global mean cooling, decreases in land temperature, precipitation, and runoff in the pulse case are much larger than that in the sustained case. The spatial pattern changes differ substantially between these two cases. Thus, direct extrapolations from volcanic eruption observations provide limited insight into impacts of potential stratospheric aerosol geoengineering. However, simulations of volcanic eruptions can be useful to test process representations in models that are used to simulate geoengineering deployments.
Plain Language Summary: Major volcanic eruptions are considered as natural analogues for stratospheric sulfate aerosol geoengineering that aims to cool the climate by increasing the burden of stratospheric sulfate aerosols. Volcanic eruptions produce a layer of sulfate aerosols that stays in the stratosphere for a couple of years, whereas geoengineering efforts would need to sustain the aerosol layer persistently to counteract CO2-induced warming. Here we use a climate model to compare climate changes in response to a volcano-like pulse aerosol forcing and a geoengineering-like sustained aerosol forcing. When producing similar amount of global mean cooling, the pulse aerosol forcing results in a much larger reduction in land temperature and land minus ocean temperature when compared to that induced by a sustained aerosol forcing. Also, both land precipitation and runoff decrease more in response to the pulse aerosol forcing. Spatial patterns of temperature and the hydrological cycle change also differ substantially between these two types of forcings. These differences in the climate response between the pulse forcing and sustained forcing clearly show that caution should be taken when using climate consequences of volcanic eruptions to directly infer climate responses to stratospheric aerosol geoengineering
Planar Heterojunction Solar Cell Employing a Single-Source Precursor Solution-Processed Sb2S3 Thin Film as the Light Absorber
No full textWe discuss here a solution-processed thin film of antimony trisulphide (Sb2S3; band gap approximate to 1.7 eV; electronic configuration: ns(2)np(0)) for applications in planar heterojunction (PHJ) solar cells. An alternative solution processing method involving a single-metal organic precursor, viz., metal-butyldithiocarbamic acid complex, is used to grow the thin films of Sb2S3. Because of excess sulphide in the metal complex, the formation of any oxide is nearly retarded. Sb2S3 additionally displays structural anisotropy with a ribbon-like structure along the 001] direction. These ribbon-like structures, if optimally oriented with respect to the electron transport layer (ETL)/glass substrate, can be beneficial for light-harvesting and charge-transport properties. A PHJ solar cell is fabricated comprising Sb2S3 as the light absorber and CdS as an ETL coated on to FTO. With varying film sintering temperature and thickness, the typical ribbon-like structures predominantly with planes hkl: l = 0 stacked horizontally along with respect to CdS/FTO are obtained. The morphology of the films is observed to be a function of the sintering temperature, with higher sintering temperatures yielding compact and smooth films with large-sized grains. Maximum photon to electricity efficiency of 2.38 is obtained for PHJ solar cells comprising 480 nm thick films of Sb2S3 sintered at 350 degrees C having a grain size of few micrometers (>5 mu m). The study convincingly shows that improper grain orientation, which may lead to nonoptimal alignments of the intrinsic structure with regard to the ETL/glass substrate, is not the sole parameter for determining photovoltaics performance. Other solution-processing parameters can still be suitably chosen to generate films with optimum morphology, leading to high photon to electricity efficiency
Search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks in proton�proton collisions at �s=13Te
No full textA search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton�proton collisions at a center-of-mass energy of 13Te collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9fb-1. The signal is characterized by a large missing transverse momentum recoiling against a bottom quark�antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of limits both on parameters of the type-2 two-Higgs doublet model extended by an additional light pseudoscalar boson a (2HDM+a) and on parameters of a baryonic Z � simplified model. The 2HDM+a model is tested experimentally for the first time. For the baryonic Z � model, the presented results constitute the most stringent constraints to date. © 2019, CERN for the benefit of the CMS collaboration
Single and dual adhesive bond strength analysis of single lap joint between dissimilar adherends
No full textThe emerging trends for joining of aircraft structural parts made up of different materials are essential for structural optimization. Adhesively bonded joints are widely used in the aircraft structural constructions for joining of the similar and dissimilar materials. The bond strength mainly depends on the type of adhesive and its properties. Dual adhesive bonded single lap joint concept is preferred where there is large difference in properties of the two dissimilar adherends and demanding environmental conditions. In this work, Araldite-2015 ductile and AV138 brittle adhesives have been used separately between the dissimilar adherends such as, CFRP and aluminium adherends. In the dual adhesive case, the ductile adhesive Araldite-2015 has been used at the ends of the overlap because of high shear and peel strength, whereas in the middle of the bonded region the brittle adhesive AV138 has been used at different dimensions. The bond strength and corresponding failure patterns have been evaluated. The Digital Image Correlation (DIC) method has been used to monitor the relative displacements between the dissimilar adherends. Finite element analysis (FEA) has been carried-out using ABAQUS software. The variation of peel and shear stresses along the single and dual adhesive bond length have been captured. Comparison of experimental and numerical studies have been carried-out and the results of numerical values are closely matching with the experimental values. From the studies it is found that, the use of dual adhesive helps in increasing the bond strength