4-(4-Nitro­benzene­sulfonamido)pyridinium trifluoro­acetate

In the title compound, C11H10N3O4S+·C2F3O2 −, the benzene ring makes an angle of 87.3 (2)° with the pyridinium ring. The nitro group is essentially coplanar with the benzene ring. The F atoms of the CF3 group are disordered over two positions with almost equal occupancy [0.531 (12)/0.469 (12)]. The crystal structure is stabilized by N—H⋯O and C—H⋯O hydrogen bonds

A Modified Decision Tree Algorithm Based on Genetic Algorithm for Mobile User Classification Problem

In order to offer mobile customers better service, we should classify the mobile user firstly. Aimed at the limitations of previous classification methods, this paper puts forward a modified decision tree algorithm for mobile user classification, which introduced genetic algorithm to optimize the results of the decision tree algorithm. We also take the context information as a classification attributes for the mobile user and we classify the context into public context and private context classes. Then we analyze the processes and operators of the algorithm. At last, we make an experiment on the mobile user with the algorithm, we can classify the mobile user into Basic service user, E-service user, Plus service user, and Total service user classes and we can also get some rules about the mobile user. Compared to C4.5 decision tree algorithm and SVM algorithm, the algorithm we proposed in this paper has higher accuracy and more simplicity

4-(2-Nitro­benzene­sulfonamido)pyri­dinium trifluoro­acetate

In the title compound, C11H10N3O4S+·C2F3O2 −, the dihedral angle between the benzene ring and the pyridinium ring is 88.7 (4)°. In the crystal structure, a network of N—H⋯O, C—H⋯O and C—H⋯F hydrogen bonds links the constituent ions. One O atom of the nitro group is disordered over two positions, with site-occupancy factors of 0.57 (2) and 0.43 (2)

Poly[[μ2-aqua-aqua­(μ3-3,5-dinitro­salicylato)barium(II)] monohydrate]

In the title coordination polymer, {[Ba(C7H2N2O7)(H2O)2]·H2O}n, the BaII atom is ten-coordinated by seven O atoms from four 3,5-dinitro­salicylatate ligands, two μ2-bridging aqua ligands and one water mol­ecule. The coordination mode is best described as a bicapped square-anti­prismatic geometry. The 3,5-dinitrosalicylatate ligands bridge three Ba atoms. Centrosymmetrically related dinuclear barium units, with a Ba⋯Ba separation of 4.767 (5) Å, form infinite chains, which are further self-assembled into a supra­molecular network through inter­molecular O—H⋯O hydrogen-bonding inter­actions between O atoms of 3,5-dinitro­salicylatate ligands and water mol­ecules

Maximum gravitational mass MTOV=2.25−0.07+0.08M⊙M_{\rm TOV}=2.25^{+0.08}_{-0.07}M_\odot inferred at about 3%3\% precision with multimessenger data of neutron stars

The maximal gravitational mass of nonrotating neutron stars ($M_{\rm TOV}$) is one of the key parameters of compact objects and only loose bounds can be set based on the first principle. With reliable measurements of the masses and/or radii of the neutron stars, $M_{\rm TOV}$ can be robustly inferred from either the mass distribution of these objects or the reconstruction of the equation of state (EoS) of the very dense matter. For the first time we take the advantages of both two approaches to have a precise inference of $M_{\rm TOV}=2.25^{+0.08}_{-0.07}~M_\odot$ (68.3% credibility), with the updated neutron star mass measurement sample, the mass-tidal deformability data of GW170817, the mass-radius data of PSR J0030+0451 and PSR J0740+6620, as well as the theoretical information from the chiral effective theory ($\chi$EFT) and perturbative quantum chromodynamics (pQCD) at low and very high energy densities, respectively. This narrow credible range is benefited from the suppression of the high $M_{\rm TOV}$ by the pQCD constraint and the exclusion of the low $M_{\rm TOV}$ by the mass function. Three different EoS reconstruction methods are adopted separately, and the resulting $M_{\rm TOV}$ are found to be almost identical. This precisely evaluated $M_{\rm TOV}$ suggests that the EoS of neutron star matter is just moderately stiff and the $\sim 2.5-3M_\odot$ compact objects detected by the second generation gravitational wave detectors are most likely the lightest black holes.Comment: 12 pages, 6 figure

Silicon nitride metalenses for unpolarized high-NA visible imaging

As one of nanoscale planar structures, metasurface has shown excellent superiorities on manipulating light intensity, phase and/or polarization with specially designed nanoposts pattern. It allows to miniature a bulky optical lens into the chip-size metalens with wavelength-order thickness, playing an unprecedented role in visible imaging systems (e.g. ultrawide-angle lens and telephoto). However, a CMOS-compatible metalens has yet to be achieved in the visible region due to the limitation on material properties such as transmission and compatibility. Here, we experimentally demonstrate a divergent metalens based on silicon nitride platform with large numerical aperture (NA~0.98) and high transmission (~0.8) for unpolarized visible light, fabricated by a 695-nm-thick hexagonal silicon nitride array with a minimum space of 42 nm between adjacent nanoposts. Nearly diffraction-limit virtual focus spots are achieved within the visible region. Such metalens enables to shrink objects into a micro-scale size field of view as small as a single-mode fiber core. Furthermore, a macroscopic metalens with 1-cm-diameter is also realized including over half billion nanoposts, showing a potential application of wide viewing-angle functionality. Thanks to the high-transmission and CMOS-compatibility of silicon nitride, our findings may open a new door for the miniaturization of optical lenses in the fields of optical fibers, microendoscopes, smart phones, aerial cameras, beam shaping, and other integrated on-chip devices.Comment: 16 pages, 7 figure