8,617 research outputs found
Irradiation of benzene molecules by ion-induced and light-induced intense fields
Benzene, with its sea of delocalized -electrons in the valence orbitals,
is identified as an example of a class of molecules that enable establishment
of the correspondence between intense ion-induced and laser-light-induced
fields in experiments that probe ionization dynamics in temporal regimes
spanning the attosecond and picosecond ranges.Comment: 4 ps figure
Galactic Bulge Population II Cepheids in the VVV Survey: Period-Luminosity Relations and a Distance to the Galactic Center
We present the near-infrared observations of population II Cepheids in the
Galactic bulge from VVV survey. We identify 340 population II Cepheids in the
Galactic bulge from VVV survey based on their match with OGLE-III Catalogue.
The single-epoch and multi-epoch observations complement the
accurate periods and optical mean-magnitudes from OGLE. The sample
consisting of BL Herculis and W Virginis subtypes is used to derive
period-luminosity relations after correcting mean-magnitudes for the
extinction. Our -band period-luminosity relation, , is consistent with published work
for BL Herculis and W Virginis variables in the Large Magellanic Cloud. We
present a combined OGLE-III and VVV catalogue with periods, classification,
mean magnitudes and extinction for 264 Galactic bulge population II Cepheids
having good-quality -band light curves. The absolute magnitudes for
population II Cepheids and RR Lyraes calibrated using Gaia and Hubble Space
Telescope parallaxes, together with calibrated magnitudes for Large Magellanic
Cloud population II Cepheids, are used to obtain a distance to the Galactic
center, , which
changes by with different extinction laws. While noting the
limitation of small number statistics, we find that the present sample of
population II Cepheids in the Galactic bulge shows a nearly spheroidal spatial
distribution, similar to metal-poor RR Lyrae variables. We do not find evidence
of the inclined bar as traced by the metal-rich red-clump stars. The number
density for population II Cepheids is more limited as compared to abundant RR
Lyraes but they are bright and exhibit a wide range in period that provides a
robust period-luminosity relation for an accurate estimate of the distance to
the Galactic center.Comment: 9 pages, 8 figures, Accepted for publication in A&
Crystal structure of a mixed solvated form of amoxapine acetate
The mixed solvated salt 4-(2-chlorodibenzo[b,f][1,4]oxazepin-11-yl)piperazin-1-ium acetate-acetic acid-cyclohexane (2/2/1), C17H17ClN3O+·C2H3O2-·C2H4O2·0.5C6H12, crystallizes with one molecule of protonated amoxapine (AXPN), an acetate anion and a molecule of acetic acid together with half a molecule of cyclohexane. In the centrosymmetric crystal, both enantiomers of the protonated AXPN molecule stack alternatively along [001]. Acetate anions connect the AXPN cations through N-H...O hydrogen bonding in the [010] direction, creating a sheet lying parallel to (100). The acetic acid molecules are linked to the acetate anions via O-H...O hydrogen bonds within the sheets. Within the sheets there are also a number of C-H...O hydrogen bonds present. The cyclohexane solvent molecules occupy the space between the sheets
The propensity of molecules to spatially align in intense light fields
The propensity of molecules to spatially align along the polarization vector
of intense, pulsed light fields is related to readily-accessible parameters
(molecular polarizabilities, moment of inertia, peak intensity of the light and
its pulse duration). Predictions can now be made of which molecules can be
spatially aligned, and under what circumstances, upon irradiation by intense
light. Accounting for both enhanced ionization and hyperpolarizability, it is
shown that {\it all} molecules can be aligned, even those with the smallest
static polarizability, when subjected to the shortest available laser pulses
(of sufficient intensity).Comment: 8 pages, 4 figures, to be submitted to PR
Electron attachment to valence-excited CO
The possibility of electron attachment to the valence state of CO
is examined using an {\it ab initio} bound-state multireference configuration
interaction approach. The resulting resonance has symmetry;
the higher vibrational levels of this resonance state coincide with, or are
nearly coincident with, levels of the parent state. Collisional
relaxation to the lowest vibrational levels in hot plasma situations might
yield the possibility of a long-lived CO state.Comment: Revtex file + postscript file for one figur
From discovery to scale-up: alpha-lipoic acid : nicotinamide co-crystals in a continuous oscillatory baffled crystalliser
The crystalline nutritional supplement alpha-lipoic acid degrades rapidly on exposure to temperatures above its melting point 65 degrees C and to light. A small-scale experimental co-crystal screen has produced three novel co-crystals of alpha-lipoic acid that each display enhanced thermal stability and differences in aqueous solubilities compared to alpha-lipoic acid. In each case, the initial screening procedure produced tens of milligrams of material enabling initial identification, characterisation and crystal structure determination. The structure of the alpha-lipoic acid : nicotinamide co-crystal was determined by single crystal X-ray diffraction and used for subsequent phase identification. Scale-up of the co-crystallisation process of alpha-lipoic acid with nicotinamide was then investigated in a continuous oscillatory baffled crystalliser. Over 1 kg of solid co-crystals was produced using a continuous crystallisation process in a continuous oscillatory baffled crystalliser at a throughput of 350 g h-1 yielding a purity of 99% demonstrating this as an effective route to rapid scale-up of a novel co-crystal system
From discovery to scale-up: alpha-lipoic acid : nicotinamide co-crystals in a continuous oscillatory baffled crystalliser
The crystalline nutritional supplement alpha-lipoic acid degrades rapidly on exposure to temperatures above its melting point 65 degrees C and to light. A small-scale experimental co-crystal screen has produced three novel co-crystals of alpha-lipoic acid that each display enhanced thermal stability and differences in aqueous solubilities compared to alpha-lipoic acid. In each case, the initial screening procedure produced tens of milligrams of material enabling initial identification, characterisation and crystal structure determination. The structure of the alpha-lipoic acid : nicotinamide co-crystal was determined by single crystal X-ray diffraction and used for subsequent phase identification. Scale-up of the co-crystallisation process of alpha-lipoic acid with nicotinamide was then investigated in a continuous oscillatory baffled crystalliser. Over 1 kg of solid co-crystals was produced using a continuous crystallisation process in a continuous oscillatory baffled crystalliser at a throughput of 350 g h-1 yielding a purity of 99% demonstrating this as an effective route to rapid scale-up of a novel co-crystal system
Uterine primitive neuroectodermal tumor with adenosarcoma: a case report
<p>Abstract</p> <p>Introduction</p> <p>Primitive neuroectodermal tumor of the uterus is extremely rare. They occur as either pure primitive neuroectodermal tumors or admixed with neoplasms of mullerian origin.</p> <p>Case presentation</p> <p>A case of uterine primitive neuroectodermal tumor with adenosarcoma in a 50-year-old Asian Indian woman is presented. Histologically, the neoplasm displayed perivascular pseudorosettes and occasional Homer-Wright rosettes. A strong positivity for neuronspecific enolase and synaptophysin was noted, while chromogranin and CD99 were negative. Merging imperceptibly with the neuroectodermal components were the areas of adenosarcoma.</p> <p>Conclusion</p> <p>To the best of our knowledge, this report represents the second case of a uterine primitive neuroectodermal tumor with an admixed adenosarcoma.</p
Surface Wear Studies in Some Materials Using α-induced Reactions
The radio-activity produced during the irradiation of 63,65Cu, 59Co, 93Nb and 121,123Sb targets with α-particles have been measured using activation technique. he yields of radioactive isotopic products 66,67,68 Ga, 61 Cu, 96g,mTc and 123,124,126I have been determined in the energy range ≈ 10-40 MeV using stacked foil Technique. Radioactive counting of samples was performed with a high-resolution gamma-spectrometer. As light ion beams produce an extremely narrow layer of activities in the surface of a material, these reactions may be useful for thin layer activation study
High Harmonic Spectroscopy of the Cooper Minimum in Molecules
The Cooper minimum (CM) has been studied using high harmonic generation solely in atoms. Here, we present detailed experimental and theoretical studies on the CM in molecules probed by high harmonic generation using a range of near-infrared light pulses from λ = 1.3 to 1.8 µm. We demonstrate the CM to occur in CS₂ and CCl₄ at ~42 and ~40 eV, respectively, by comparing the high harmonic spectra with the known partial photoionization cross sections of different molecular orbitals, confirmed by theoretical calculations of harmonic spectra. We use CM to probe electron localization in Cl-containing molecules (CCl₄, CH₂Cl₂, and trans-C₂H₂Cl₂) and show that the position of the minimum is influenced by the molecular environment
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