We present a combined study of the thermal expansion and the thermal conductivity of the perovskite series $R{\text{CoO}}_{3}$ with $R=\text{La}$, Nd, Pr, and Eu. The well-known spin-state transition in ${\text{LaCoO}}_{3}$ is strongly affected by the exchange of the $R$ ions due to their different ionic radii, i.e., chemical pressure. This can be monitored in detail by measurements of the thermal expansion, which is a highly sensitive probe for detecting spin-state transitions. The Co ions in the higher spin state act as additional scattering centers for phonons, therefore suppressing the phonon thermal conductivity. Based on the analysis of the interplay between spin-state transition and heat transport, we present a quantitative model of the thermal conductivity for the entire series. In ${\text{PrCoO}}_{3}$, an additional scattering effect is active at low temperatures. This effect arises from the crystal-field splitting of the $4f$ multiplet, which allows for resonant scattering of phonons between the various $4f$ levels.
Background: Magnetic resonance imaging (MRI) is generally contraindicated for patients with a pacemaker (PM) or implantable cardiac defibrillator (ICD), because of the risk of life-threatening interference with the device.Nevertheless, the question whether to perform MRI despite the presence of these devices can still arise when MRI is vitally indicated.In some hospitals, special precautionary measures are taken so that MRI can be performed in such cases.Methods: This review is based on the authors' experience in 42 patients who underwent MRI at our university hospital, on the pertinent literature, and on the recommendations of medical societies.Results: Because of its excellent image quality, MRI is often an indispensable diagnostic tool.Structured multidisciplinary management enables it to be performed safely even in patients with a PM or ICD.Pre-and post-MRI checks of the device are recommended, as well as extensive monitoring and the availability of the necessary personnel to deal with an emergency.In general, the pacing and defibrillator functions should be deactivated; for pacemakerdependent patients, the asynchronous pacing mode should be activated.No serious incidents have occurred when these precautions have been observed, either among our own patients or in the literature.Newer PM systems have been approved for MRI scanning under certain conditions. Conclusion:In patients with a PM or ICD, the benefit of MRI may far outweigh its risks if the indication has been established for the particular patient as an interdisciplinary decision and if the appropriate precautions are observed during scanning.Now that newer PM systems have been approved for MRI scanning, the problem seems close to being solved.
Abstract Intact human platelets bind cytochalasin B (CB) with a capacity of 100– 120 p mols CB/mg protein or approximately 7 × 10 4 molecules/cell and dissociation constants (K D ) ranging from 2 × 10 −8 to 10 −6 M. Up to 85% of this saturable binding is displaced by 10 −5 M cytochalasin E (CE). This CE‐sensitive binding also appears heterogeneous with K D similar to those of the overall binding. The CE‐insensitive binding, however, appears as a single component with K D ≌ 4 × 10 −7 M. The sedimentable constituents from frozen, thawed, and washed cells also bind CB with K D ranging from 2.4 × 10 −8 to 1.5 × 10 −6 M and a total capacity of approximately 39 p mols/mg protein which accounts for only 4% of the ligand binding to the intact cell. The major portion (60–80%) of this CB binding is displaceable by 500 mM D‐glucose and has a K D of 1.5 × 10 −6 M, while only 10–15% is CE‐sensitive with a K D of 2.4 ± 10 −8 M. It is concluded that 95% of the saturable CB binding in platelets is associated with the cytosol of which 80–85% is sensitive to CE and that only 3% of the cellular binding is glucose sensitive, membrane‐associated binding. If the CE‐sensitive binding associated with the cytosol is entirely to actin, the stoichiometry of this binding is approximately one CB to 30 actin monomers, which is greater by an order of magnitude than that for CB binding to muscle actin.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDissociation of myosin in acidSara Szuchet and C. Richard ZobelCite this: Biochemistry 1974, 13, 7, 1482–1491Publication Date (Print):March 1, 1974Publication History Published online1 May 2002Published inissue 1 March 1974https://pubs.acs.org/doi/10.1021/bi00704a026https://doi.org/10.1021/bi00704a026research-articleACS PublicationsRequest reuse permissionsArticle Views22Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
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