683 research outputs found
Quinoxaline: Z′ = 1 form
A new Z′ = 1 crystal structure of quinoxaline (or 1,4-diazanaphthalene), C8H6N2, with one-fifth the volume of the earlier known Z′ = 5 structure was obtained by means of an in situ cryocrystallization technique
1,2,3-Trifluorobenzene
In the title compound, C6H3F3, weak electrostatic and dispersive forces between C(δ+)—F(δ−) and H(δ+)—C(δ−) groups are at the borderline of the hydrogen-bond phenomenon and are poorly directional and further deformed in the presence of π–π stacking interactions. The molecule lies on a twofold rotation axis. In the crystal structure, one-dimensional tapes are formed via two antidromic C—H⋯F hydrogen bonds. These tapes are, in turn, connected into corrugated two-dimensional sheets by bifurcated C—H⋯F hydrogen bonds. Packing in the third dimension is furnished by π–π stacking interactions with a centroid–centroid distance of 3.6362 (14) Å
1,3-Difluorobenzene
The weak electrostatic and dispersive forces between C(δ+)—F(δ−) and H(δ+)—C(δ−) are at the borderline of the hydrogen-bond phenomenon and are poorly directional and further deformed in the presence of other dominant interactions, e.g. C—H⋯π. The title compound, C6H4F2, Z′ = 2, forms one-dimensional tapes along two homodromic C—H⋯F hydrogen bonds. The one-dimensional tapes are connected into corrugated two-dimensional sheets by further bi- or trifrucated C—H⋯F hydrogen bonds. Packing in the third dimension is controlled by C—H⋯π interactions
Curating Transient Population in Urban Dynamics System
For past several decades, research efforts in population modelling has proven
its efficacy in understanding the basic information about residential and
commercial areas, as well as for the purposes of planning, development and
improvement of the community as an eco-system. More or less, such efforts
assume static nature of population distribution, in turn limited by the current
ability to capture the dynamics of population change at a finer resolution of
space and time. Fast forward today, more and more people are becoming mobile,
traveling across borders impacting the nuts and bolts of our urban fabric.
Unfortunately, our current efforts are being surpassed by the need to capture
such transient population. It is becoming imperative to identify and define
them, as well as measure their dynamics and interconnectedness. In this work,
we intend to research urban population mobility patterns, gauge their transient
nature, and extend our knowledge of their visited locations. We plan to achieve
this by designing and developing novel methods and using VGI data that models
and characterizes transient population dynamics
On the optical properties of Ag^{+15} ion-beam irradiated TiO_{2} and SnO_{2} thin films
The effects of 200-MeV Ag^{+15} ion irradiation on the optical properties of
TiO_{2} and SnO_{2} thin films prepared by using the RF magnetron sputtering
technique were investigated. These films were characterized by using UV-vis
spectroscopy, and with increasing irradiation fluence, the transmittance for
the TiO_{2} films was observed to increase systematically while that for
SnO_{2} was observed to decrease. Absorption spectra of the irradiated samples
showed minor changes in the indirect bandgap from 3.44 to 3.59 eV with
increasing irradiation fluence for TiO_{2} while significant changes in the
direct bandgap from 3.92 to 3.6 eV were observed for SnO_{2}. The observed
modifications in the optical properties of both the TiO_{2} and the SnO_{2}
systems with irradiation can be attributed to controlled structural
disorder/defects in the system.Comment: 6 pages, ICAMD-201
Electronic structure studies of Fe- ZnO nanorods by x-ray absorption fine structure
We report the electronic structure studies of well characterized
polycrystalline Zn_{1-x}Fe_xO (x = 0.0, 0.01, 0.03, and 0.05) nanorods
synthesized by a co-precipitation method through x-ray absorption fine
structure (XAFS). X-ray diffraction (XRD) reveals that Fe doped ZnO
crystallizes in a single phase wurtzite structure without any secondary phase.
From the XRD pattern, it is observed that peak positions shift towards lower
2\theta value with Fe doping. The change in the peak positions with increase in
Fe contents clearly indicates that Fe ions are replacing Zn ions in the ZnO
matrix. Linear combination fittings (LCF) at Fe K-edge demonstrate that Fe is
in mixed valent state (Fe3+/Fe2+) with a ratio of ~ 7:3 (Fe3+:Fe2+). XAFS data
is successfully fitted to wurtzite structure using IFEFFIT and Artemis. The
results indicate that Fe substitutes Zn site in the ZnO matrix in tetrahedral
symmetry.Comment: 7 pages, 5 figures, 2 tables, regular articl
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