Magnetic anisotropy of the antiferromagnetic ring [Cr(8)F(8)PiV(16)]
CHEMISTRY-A EUROPEAN JOURNAL
Authors: van Slageren, J; Sessoli, R; Gatteschi, D; Smith, AA; Helliwell, M; Winpenny, REP; Cornia, A; Barra, AL; Jansen, AGM; Rentschler, E; Timco, GA
Abstract
A new tetragonal (P42(1)2) crystalline form of [Cr(8)F(8)Piv(16)] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the unit cell, form almost perfectly planar, regular octagons. The interaction between the Cr-III ions is antiferromagnetic (J = 12 cm(-1)) which results in a S = 0 spin ground state, The low-lying spin excited states were investigated by cantilever torque magnetometry (CTM) and high-frequency EPR (HFEPR). The compound shows hard-axis anisotropy. The axial zero-field splitting (ZFS) parameters of the first two spin excited states (S = 1 and S = 2, respectively) are D-1 = 1.59(3) cm(-1) or 1.63 cm(-1) (from CTM and HFEPR, respectively) and D-2 0.37 cm(-1) (from HFEPR). The dipolar contributions to the ZFS of the S = 1 and S = 2 spin states were calculated with the point dipolar approximation. These contributions proved to be less than the combined single-ion contributions. Angular overlap model calculations that used parameters obtained from the electronic absorption spectrum, showed that the unique axis of the single-ion ZFS is at an angle of 19.3(1)degrees with respect to the ring axis. The excellent agreement between the experimental and the theoretical results show the validity of the used methods for the analysis of the magnetic anisotropy in antiferromagnetic Cr-III rings.
Legionnaires' disease mimicking swine influenza (H1N1) pneumonia during the "herald wave" of the pandemic
HEART & LUNG
Authors: Cunha, Burke A.; Klein, Natalie C.; Strollo, Stephanie; Syed, Uzma; Mickail, Nardeen; Laguerre, Marianne
Abstract
BACKGROUND: New York area hospitals were hit hard by the swine influenza (H1N1) pandemic in spring and summer 2009. During a pandemic, the initial cases may be difficult to recognize, but subsequent clinical diagnoses were relatively straightforward, given the high volume of cases and their typical clinical presentation. Swine influenza pneumonia presents as an influenza-like illness (ILI) with dry cough, fever > 102 degrees F and myalgias. A variety of other viral pneumonias, eg, cytomegalovirus, human parainfluenza virus 3 (HPIV 3), and adenovirus, as well as bacterial community-acquired pneumonias (CAPS) that may present with some of the clinical and laboratory features of H1N1 pneumonia. Most adults admitted to hospitals with ILIs during the pandemic had, in fact, definite or probable H1N1 pneumonia. The Infectious Disease Division at Winthrop-University Hospital developed a diagnostic weighted point score to identify probable H I NI cases in hospitalized adults with rapid negative influenza diagnostic tests (RIDTs). METHODS: We present a case of an elderly male who presented with an ILI and negative RIDTs during the H1N1 pandemic. He was admitted with a diagnosis of possible H1N1, and placed on influenza precautions and oseltamivir. Although the patient had features consistent with H1N1 pneumonia, Legionnaires' disease was included in the differential diagnosis because of his elevated serum ferritin levels. A Legionella urinary antigen test was positive for Legionella pneumophila (serogroups 01-06). RESULTS: The peak seasonal incidence of sporadic Legionnaires' disease occurs in the summer and fall. Even in the midst of a pandemic, clinicians should be on the alert for other infectious diseases that may mimic H1N1 pneumonia. In our experience, the best way to differentiate H1N1 from ILIs or other bacterial CAPs is through the Winthrop-University Hospital Infectious Disease Division's diagnostic weighted point score system for H1N1 pneumonia or its rapid simplified version, ie, the diagnostic swine influenza triad. Legionnaires' disease is the atypical CAP pathogen most likely to mimic H1N1 pneumonia. CONCLUSIONS: Based on this and other nine cases at our institution during the "herald wave" of pandemic, we conclude that Legionnaires' disease may mimic swine influenza (H1N1) pneumonia. (Heart Lung (R) 2010;39:242-248.)