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Selective reactions on structures of high complexity can move beyond the mind's eye and proof-of-principle. Enhanced understanding of noncovalent interactions and their interdependence, revealed through analysis of multiple parameters, should accelerate the discovery of efficient reactions in highly complex molecular environments.
ABSTRACT We present six epochs of optical spectropolarimetry of the Type IIP supernova (SN) 2021yja ranging from ∼25 to 95 d after the explosion. An unusually high continuum linear polarization of $p \approx 0.9~{{\ \rm per\ cent}}$ is measured during the early photospheric phase, followed by a steady decrease well before the onset of the nebular phase. This behaviour has not been observed before in Type IIP supernovae (SNe IIP). The observed continuum polarization angle does not change significantly during the photospheric phase. We find a pronounced axis of symmetry in the global ejecta that is shared in common with the Hα and Ca ii near-infrared triplet lines. These observations are consistent with an ellipsoidal geometry. The temporal evolution of the continuum polarization is also compatible with the SN ejecta interacting with aspherical circumstellar matter (CSM), although no spectroscopic features that may be associated with strong interaction can be identified. Alternatively, we consider the source of the high polarization to be an extended hydrogen envelope that is indistinguishable from low-density CSM.
Abstract : Metal-organic frameworks (MOFs) with rigid, permanently porous structures have been shown to adsorb a variety of guests, including known carcinogens; however, little is known about the capacity of MOFs for dynamic gas adsorption properties. Therefore, dynamic adsorption experiments with various gases and CWA/simulants were performed. We first prepared M-MOF-74 (M = Zn, Mg, Co, Ni) series and tested their ability to separate ammonia from both dry and wet air. In dry conditions, all of the MOFs have excellent separation capacity (greater than 1 mol/kg). In humid conditions, the uptake drops in every case, but ammonia uptake remains high. After the clear demonstration of metal effects on gas selectivity, we extended our strategy to create metalated nanoparks; we synthesized MOF-253 for successive metalation reactions. We tested the ammonia separation capacity for Cu, Zn, and Fe impregnated MOF-253 materials. Based on the dynamic loading melataed MOF-253 samples clearly outperform the pristine MOF-253, and ammonia loading values are comparable to those for M-MOF-74 series. More importantly, the metalated MOF-253 series showed significant saturation loading capacity for ammonia in a humid environment.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
We present a novel approach to measuring similarity between shapes and exploit it for object recognition. In our framework, the measurement of similarity is preceded by (1) solving for correspondences between points on the two shapes, (2) using the correspondences to estimate an aligning transform. In order to solve the correspondence problem, we attach a descriptor, the shape context, to each point. The shape context at a reference point captures the distribution of the remaining points relative to it, thus offering a globally discriminative characterization. Corresponding points on two similar shapes will have similar shape contexts, enabling us to solve for correspondences as an optimal assignment problem. Given the point correspondences, we estimate the transformation that best aligns the two shapes; regularized thin-plate splines provide a flexible class of transformation maps for this purpose. Dis-similarity between two shapes is computed as a sum of matching errors between corresponding points, together with a term measuring the magnitude of the aligning transform. We treat recognition in a nearest-neighbor classification framework. Results are presented for silhouettes, trademarks, handwritten digits and the COIL dataset.
This paper sketches a characterisation of the regime of urban marginality that has emerged in advanced societies since the close of the Fordist era, highlighting four logics that combine to produce it: a macrosocietal drift towards inequality, the mutation of wage labour (entailing both deproletarianisation and casualisation), the retrenchment of welfare states, and the spatial concentration and stigmatisation of poverty. The rise of this new marginality does not signal a transatlantic convergence on the American pattern: European neighbourhoods of relegation are deeply penetrated by the state and ethnoracial tensions in them are fuelled, not by the growing gap between immigrants and natives, but by their increasing propinquity in social and physical space. To cope with emergent forms of urban marginality, societies face a three-pronged alternative: they can patch up existing programmes of the welfare state, criminalise poverty via the punitive containment of the poor, or institute new social rights that sever subsistence from performance in the labour market.
As solar cells exceed 25% efficiency, photon management becomes far more important than electronic properties. Surprisingly, maximizing external fluorescence increases efficiency, the key behind the recent single-junction efficiency record of 28.4%.
This disclosure provides systems, methods, and apparatus related to nanostructures. In one aspect, an array of nanowires is provided. The array of nanowires comprises a plurality of nanowires. End of nanowires of the plurality of nanowires are attached to a substrate. A liquid including a plurality of nanoparticles is deposited on the array of nanowires. The liquid is evaporated from the array of nanowires. Nanoparticles of the plurality of nanoparticles are deposited on the nanowires as a meniscus of the liquid recedes along lengths of the plurality of nanowires.
A series of “diamond-core” bridged dinuclear first-row transition metal complexes with the dinucleating ligand DPFN are prepared and characterized.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
