2,418 research outputs found
Core excitation in Ozone localized to one of two symmetry-equivalent chemical bonds - molecular alignment through vibronic coupling
Core excitation from terminal oxygen O in O is shown to be an
excitation from a localized core orbital to a localized valence orbital. The
valence orbital is localized to one of the two equivalent chemical bonds. We
experimentally demonstrate this with the Auger Doppler effect which is
observable when O is core-excited to the highly dissociative
O1s7a state. Auger electrons emitted from the atomic oxygen
fragment carry information about the molecular orientation relative to the
electromagnetic field vector at the moment of excitation. The data together
with analytical functions for the electron-peak profiles give clear evidence
that the preferred molecular orientation for excitation only depends on the
orientation of one bond, not on the total molecular orientation. The
localization of the valence orbital "7a" is caused by mixing of the valence
orbital "5b" through vibronic coupling of anti-symmetric stretching mode
with b-symmetry. To the best of our knowledge, it is the first discussion
of the localization of a core excitation of O. This result explains the
success of the widely used assumption of localized core excitation in
adsorbates and large molecules
Titan cell production in Cryptococcus neoformans reshapes the cell wall and capsule composition during infection
This work was supported by the National Institutes of Health (R01AI080275 and R21AI22352), the NIH Fogarty International Center (R25TW009345), the University of Minnesota Center for Translational Science Institute (UL1TR000114), Wellcome Trust (086827, 075470, 097377, 101873 & 200208) and MRC Centre for Medical Mycology (N006364/1). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.Peer reviewedPublisher PD
Unusual cross-sectional imaging findings in hepatic peliosis
Abstract.: Hepatic peliosis is a rare entity that represents focal, multifocal, segmental, or diffuse dilatation of liver sinusoids. Hepatic peliosis is often associated with chronic wasting diseases but also has been reported in association with anabolic, contraceptive, or other hormonal treatment, and even in context with HIV-related bacterial infections. Hepatic peliosis is usually clinically unapparent and mostly found only during autopsy, but occasionally it may lead to diagnostic problems if detected radiologically since the imaging findings in hepatic peliosis are quite variable according to the variety of its possible histologic features as well as the possibility of additional hemorrhage. We present a case of hepatic peliosis associated with bronchial carcinoma that showed moderate centripetal enhancement during the portal-venous phase on CT, pronounced venous pooling on contrast enhanced T1-weighted images acquired during the hepatic-venous phase, and bright signal on T2-weighted images, thus mimicking in some way a capillary hemangioma. We also discuss some not yet described CT and MR features of this rare entity which should be included into the differential diagnosis of atypical liver lesions in patients with the above-mentioned condition
Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass
The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment
Off the Page: Reconstructing/Re-imagining a Dance Score
PosterThe idea for Schrifftanz Zwei, a collaboration between two choreographers, an archivist, a composer, and an animator, began at the Digital Humanities conference where four DHers decided to collaborate to re-imagine a dance score housed in the Irmgard Bartenieff Papers at the University of Maryland. Created in 1927 by Irmgard Bartenieff, founder of the Laban/Bartenieff Institute for Movement Studies, the score was discovered during processing of her papers, along with 3 other scores of original works. Fairly fluent in Schrifttanz, Laban’s initial label for his notation system, Bartenieff began composing dances while studying with him in 1926-1929, yet she wasn’t yet an expert in his notation system. Instead, she used her own hybrid system consisting of symbols, word descriptions, and colour to describe the dance movement and space. Fascinated by the imagery in words and image, the four collaborators are creating a filmed work with both analog and digital components: Schrifttanz Zwei. The proposed poster will show the score, translations, and images of the reconstruction.University of Maryland Libraries Research Fun
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