Michael Walls

Improved Detection of Myocardial Involvement in Acute Inflammatory Cardiomyopathies Using T2 Mapping

Background— T2-weighted cardiac magnetic resonance imaging is useful in diagnosing acute inflammatory myocardial diseases, such as myocarditis and tako-tsubo cardiomyopathy (TTCM). We hypothesized that quantitative T2 mapping could better delineate myocardial involvement in these disorders versus T2-weighted imaging. Methods and Results— Thirty patients with suspected myocarditis or TTCM, referred for cardiac magnetic resonance imaging, who met established diagnostic criteria underwent myocardial T2 mapping. T2 values were averaged in involved and remote myocardial segments, both defined by a reviewer blinded to T2 data. In myocarditis, T2 was 65.2±3.2 ms in the involved myocardium versus 53.5±2.1 ms in the remote myocardium (P<0.001). In TTCM, T2 was 65.6±4.0 ms in the involved myocardium versus 53.6±2.7 ms in the remote segments (P<0.001). T2 values were similar across remote myocardial segments in patients and all myocardial segments in controls (P>0.05 for all). T2 maps provided diagnostic data even in patients with difficulty breath holding. A T2 cutoff of 59 ms identified areas of myocardial involvement, with sensitivity and specificity of 94% and 97%, respectively. T2 mapping revealed regions of abnormal T2 beyond those identified by wall motion abnormalities or late gadolinium-enhancement positivity. Conventional T2-weighted short tau inversion recovery images were uninterpretable in 7 patients because of artifact and unremarkable in 2 patients who had elevated T2 values. T2-prepared steady-state–free precession images showed areas of signal hyperintensity in only 17 of 30 patients. Conclusions— Quantitative T2 mapping reliably identifies myocardial involvement in patients with myocarditis and TTCM. T2 mapping delineated a greater extent of myocardial disease in both conditions compared with that identified by wall motion abnormalities, T2-weighted short tau inversion recovery imaging, T2-prepared steady-state–free precession, or late gadolinium enhancement. Quantitative T2 mapping warrants consideration as a robust technique to identify myocardial injury in patients with acute myocarditis or TTCM.

Composition, structure and properties of the oxide films formed on the stainless steel 316L in a primary type PWR environment

Abstract This paper reports a comprehensive study of the chemical composition, structure and electrochemical behaviour of oxide films developed on 316L stainless steel in a primary medium (1000 ppm B, 2ppm Li, 37ppm H 2 at 350 °C). The methods used are glow discharge optical spectfoscopy, grazing X-ray diffraction analysis, near field microscopy, transmission electron microscopy (TEM), Raman spectrometry and electrochemical measurements. According to the analytical and structural investigations, the outermost part of the film consists of the Ni 0.75 Fe 2.25 O 4 inverse spinel. In the intermediate part both Ni 0.75 Fe 2.25 O 4 and Fe 3 O 4 inverse spinels can be detected. Finally, the inner part of the film consists of mixed chromium oxides (Cr 2 O 3 + FeCr 2 O 4 ) and Fe 3 O 4 . The electrochemical study carried out by capacitance measurements (Mott-Schottky approach) shows that the inner and outer parts of the film manifest different semiconductivities. This is in agreement with the known semiconducting properties of the type of oxides concerned.

Kinetics of conditioning layer formation on stainless steel immersed in seawater

Adhesion of microorganisms to surfaces in marine environments leads to biofouling. The deleterious effects of biofilm growth in the marine environment are numerous and include energy losses due to increased fluid frictional resistance or to increased heat transfer resistance, the risk of corrosion induced by microorganisms, loss of optical properties, and quality control and safety problems. Antifouling agents are generally used to protect surfaces from such a biofilm. These agents are toxic and can be persistent, causing harmful environmental and ecological effects. Moreover, the use of biocides and regular cleaning considerably increase the maintenance costs of marine industries. An improved knowledge of bio‐film adhesion mechanisms is needed for the development of an alternative approach to the currently used antifouling agents. The aim of this study is to characterise the chemical composition of the molecules first interacting with stainless steel during the period immediately following immersion in natural seawater and to elucidate the kinetics of the adsorbtion process. Proteins are shown to adhere very rapidly, closely followed by carbohydrates. The distribution on the surface of organic molecules is also examined. The ad‐sorbate on the surface is not a continuous film but a heterogeneous deposit, whose average thickness varies widely. The cleaning procedures used affect the adsorption kinetics. In particular, cleaning with hexane results in slower adsorption of nitrogen‐containing species than does cleaning in acetone.

Automated quantification of mitral inflow and aortic outflow stroke volumes by three-dimensional real-time volume color-flow Doppler transthoracic echocardiography: comparison with pulsed-wave Doppler and cardiac magnetic resonance imaging.

BACKGROUND The aim of this study was to compare the feasibility, accuracy, and reproducibility of automated quantification of mitral inflow and aortic stroke volumes (SVs) using real-time three-dimensional volume color-flow Doppler transthoracic echocardiography (RT-VCFD), with cardiac magnetic resonance (CMR) imaging as the reference method. METHODS In 44 patients (86% of the screened patients) without valvular disease, RT-VCFD, CMR left ventricular short-axis cines and aortic phase-contrast flow measurement and two-dimensional (2D) transthoracic echocardiography (TTE) were performed. Dedicated software was used to automatically measure mitral inflow and aortic SVs with RT-VCFD. CMR total SV was calculated using planimetry of short-axis slices and aortic SV by phase-contrast imaging. SVs by 2D TTE were computed in the conventional manner. RESULTS The mean age of the included patients was 40 ± 16 years, and the mean left ventricular ejection fraction was 61 ± 9%. Automated flow measurements were feasible in all study patients. Mitral inflow SV by 2D TTE and RT-VCFD were 85.0 ± 21.5 and 94.5 ± 22.0 mL, respectively, while total SV by CMR was 95.6 ± 22.7 mL (P < .001, analysis of variance). On post hoc analysis, mitral inflow SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .001). The respective aortic SVs were 82.8 ± 22.3, 94.2 ± 22.3, and 93.4 ± 24.6 mL (P < .001). On post hoc analysis, aortic SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .006). The interobserver variability for SV measurements was significantly worse for 2D TTE compared with RT-VCFD. CONCLUSIONS RT-VCFD imaging with an automated quantification algorithm is feasible, accurate, and reproducible for the measurement of mitral inflow and aortic SVs and is superior to manual 2D TTE-based measurements. The rapid and automated measurements make this technique practical in the clinical setting to measure and report SVs routinely where the acoustic window will allow it, which was 86% in our study.

Mapping titanium and tin oxide phases using EELS: An application of independent component analysis

We study materials that present challenges for conventional elemental mapping techniques and can in some cases be treated successfully using independent component analysis (ICA). In this case the material in question is obtained from a TiO₂-SiO₂ solid solution that is spinodally decomposed into TiO₂ rich-SnO₂ rich multilayers. Conventional elemental mapping is difficult because the edges most easily mapped for these elements (Ti-L, Sn-M and O-K) all have onsets within the same 80 eV range. ICA is used to separate entire spectral signals corresponding to particular material phases or molecular units rather than particular elements and is thus able to distinguish between TiO₂ and SnO₂. We show that quantification of oxide species can be performed by different methods that require extra assumptions, but nevertheless should be feasible in many cases.

Interface characterization in electrodeposited Cu–Co multilayers

Multilayers of Cu–Co made by electrodeposition are characterized. The interface width and layer roughness are measured by the Fresnel technique in electron microscopy. It is shown that the quality of the interfaces is comparable to that of layers made by physical deposition techniques. By depositing the layers on a glass substrate, we also show that it is possible to measure the magnetoresistance of the multilayers without removing the substrate. The values obtained are discussed in relation to the roughness of the layers and the electrodeposition conditions.

Nanocrystallinity and the ordering of nanoparticles in two-dimensional superlattices: controlled formation of either core/shell (Co/CoO) or hollow CoO nanocrystals.

Here it is demonstrated that the diffusion process of oxygen in Co nanoparticles is controlled by their 2D ordering and crystallinity. The crystallinity of isolated Co nanoparticles deposited on a substrate does not play any role in the oxide formation. When they are self-assembled in 2D superlattices, the oxidation process is slowed and produces either core/shell (Co/CoO) nanoparticles or hollow CoO nanocrystals. This is attributed to the decrease in the oxygen diffusion rate when the nanoparticles are interdigitated. Initially, polycrystalline nanoparticles form core/shell (Co/CoO) structures, while for single-domain hexagonal close-packed Co nanocrystals, the outward diffusion of Co ions is favored over the inward diffusion of oxygen, producing hollow CoO single-domain nanocrystals.

Influence of pH on Properties of Oxide Films Formed on Type 316L Stainless Steel, Alloy 600, and Alloy 690 in High-Temperature Aqueous Environments

Abstract Oxide films formed on Type 316L (UNS S31603) stainless steel (SS), Alloy 600 (UNS N06600), and Alloy 690 (UNS N06900) in high-temperature aqueous environments of pH 5, 8, and 10, which rep...

Cationic and charge segregation in La2/3Ca1/3MnO3 thin films grown on (001) and (110) SrTiO3

Electron energy-loss spectroscopy is used to map composition and electronic states in epitaxial La2/3Ca1/3MnO3 films grown on SrTiO3 (001) and (110) substrates. It is found that in partially relaxed (110) films cationic composition and valence state of Mn3+/4+ ions are preserved across the film thickness. In contrast, in fully strained (001) films, the Ca/La ratio gradually changes across the film, being La rich at film/substrate interface and La depleted at free surface; Mn valence state changes accordingly. These observations suggest that a strongly orientation-dependent adaptative composition mechanism dominates stress accommodation in manganite films and provides microscopic understanding of their dissimilar magnetic properties.

Multi-dimensional and multi-signal approaches in scanning transmission electron microscopes

Developments in instrumentation are essential to open new fields of science. This clearly applies to electron microscopy, where recent progress in all hardware components and in digitally assisted data acquisition and processing has radically extended the domains of application. The demonstrated breakthroughs in electron optics, such as the successful design and practical realization and the use of correctors, filters and monochromators, and the permanent progress in detector efficiency have pushed forward the performance limits, in terms of spatial resolution in imaging, as well as for energy resolution in electron energy-loss spectroscopy (EELS) and for sensitivity to the identification of single atoms. As a consequence, the objects of the nanoworld, of natural or artificial origin, can now be explored at the ultimate atomic level. The improved energy resolution in EELS, which now encompasses the near-IR/visible/UV spectral domain, also broadens the range of available information, thus providing a powerful tool for the development of nanometre-level photonics. Furthermore, spherical aberration correctors offer an enlarged gap in the objective lens to accommodate nanolaboratory-type devices, while maintaining angström-level resolution for general characterization of the nano-object under study.