16 research outputs found

    Successive Phase Transitions in Fe<sup>2+</sup> Ladder Compounds Sr<sub>2</sub>Fe<sub>3</sub>Ch<sub>2</sub>O<sub>3</sub> (Ch = S, Se)

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    Small single crystals of Sr<sub>2</sub>Fe<sub>3</sub>Ch<sub>2</sub>O<sub>3</sub> (Ch = S, Se) have been synthesized by flux methods, and bulk materials have been obtained by solid state reactions. Both compounds are isostructural to the compound Sr<sub>2</sub>Co<sub>3</sub>S<sub>2</sub>O<sub>3</sub> (space group <i>Pbam</i>), which contains a novel hybrid spin ladder: a combination of a 2-leg rectangular ladder and a necklace ladder. The 2-leg ladder acts as a well-defined magnetic entity, while intimate magnetic coupling to the necklace ladder induces three successive phase transitions in the range of 40–120 K in each composition (Ch = S or Se), as revealed by Mössbauer spectroscopy, thermodynamics, and magnetometry. The complex magnetic behaviors can be explained by the unique spin–lattice topology

    Diagnosis and Anti-Reflux Therapy for GERD with Respiratory Symptoms: A Study Using Multichannel Intraluminal Impedance-pH Monitoring

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    <div><p>Background/Aims</p><p>Respiratory symptoms are often associated with gastroesophageal reflux disease (GERD). Although the role of multichannel intraluminal impedance–pH (MII-pH) monitoring in GERD is clear, little is known regarding the characteristics of patients with respiratory symptoms based on MII-pH monitoring and anti-reflux therapy. We evaluated a cohort of GERD patients to identify the MII-pH parameters of GERD-related respiratory symptoms and to assess the anti-reflux therapy outcomes.</p><p>Methods</p><p>We undertook a prospective study of patients who were referred for GERD evaluation from January 2011 to January 2012. One hundred ninety-five patients underwent MII-pH monitoring and esophageal manometry, and one hundred sixty-five patients underwent invasive anti-reflux therapy that included laparoscopic Toupet fundoplication (LTF) and the Stretta procedure. The patient characteristics and MII-pH parameters were analyzed, and the symptom scores were assessed at baseline and at 1- and 3-year follow-up evaluations.</p><p>Results</p><p>Of the 195 patients, 96 (49.2%) exhibited respiratory symptoms and significantly more reflux episodes (70.7±29.3) than patients without respiratory symptoms (64.7±24.4, <i>p</i> = 0.044) based on the MII-pH monitoring results. Moreover, the group of patients with respiratory symptoms exhibited more proximal reflux episodes (35.2±21.3) than the non-respiratory symptomatic group (28.3±17.9, <i>p</i> = 0.013). One hundred twenty-five patients following the Stretta procedure (n = 60, 31 with respiratory symptoms) or LTF (n = 65, 35 with respiratory symptoms) completed the designated 3-year follow-up period and were included in the final analysis. The symptom scores after anti-reflux therapy all decreased relative to the corresponding baseline values (<i>p</i><0.05), and there were no significant differences in the control of respiration between the Stretta procedure and LTF (<i>p</i>>0.05). However, LTF significantly reduced the recurrence (re-operation) rate compared with the Stretta procedure (0 vs. 19.4%, <i>p</i> = 0.006).</p><p>Conclusions</p><p>MII-pH monitoring effectively detected respiratory-related predictive parameters, including total/proximal reflux episodes and symptom correlations. We found that GERD patients with respiratory symptoms exhibited more proximal and total reflux episodes but not more acid-related episodes, as determined by MII-pH monitoring. Thus, such monitoring could be useful for diagnosing atypical GERD patients with respiratory symptoms. Furthermore, LTF exhibited a more significant effect on controlling typical symptoms in all GERD patients and reducing the recurrence rate than the Stretta procedure in patients with respiratory symptoms.</p></div

    Zinc Blende CoO as an Efficient CO Nondissociative Adsorption Site for Direct Synthesis of Higher Alcohols from Syngas

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    Monometallic Co0–Coδ+ catalysts have shown considerable potential in higher alcohol synthesis (HAS) direct from syngas, however, the alcohol selectivity and catalyst stability still need to be promoted. Here, we prepared a series of cobalt silicate hydroxide-derived catalysts and surprisingly obtained tetrahedrally coordinated zinc blende CoO (Z-CoO) during reduction and reaction. The nanoscale close interacted Co0-Z-CoO achieved an ROH selectivity of 64.4%, a higher alcohol (HA) selectivity of 43.6%, and a space time yield (STY) toward HA of 42.0 mmol·gCo–1·h–1, which outperformed most of the reported Co-based HAS catalysts. In addition, as a contrast, the commonly obtained rocksalt CoO (R-CoO) with octahedral structure was prepared. It is proved that Z-CoO serves as the CO nondissociative adsorption site, which exhibits a much stronger adsorption capability compared to R-CoO and Co2C, greatly facilitating the alcohol formation. Moreover, unlike the R-CoO, there were barely no phase transition of Z-CoO during HAS reaction, contributing to the catalyst stability over 550 h reaction. This work offers a facile preparation method and insights of zinc blende CoO as promising high-performance active sites for HAS

    Enrollment, group, and follow-up of the study participants.

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    <p>All patients for whom diagnostic and follow-up data were available were included in the analysis regardless of whether they discontinued treatment.</p

    Three Oxidation States of Manganese in the Barium Hexaferrite BaFe<sub>12–<i>x</i></sub>Mn<sub><i>x</i></sub>O<sub>19</sub>

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    The coexistence of three valence states of Mn ions, namely, +2, +3, and +4, in substituted magnetoplumbite-type BaFe<sub>12–<i>x</i></sub>Mn<sub><i>x</i></sub>O<sub>19</sub> was observed by soft X-ray absorption spectroscopy at the Mn-L<sub>2,3</sub> edge. We infer that the occurrence of multiple valence states of Mn situated in the pristine purely iron­(III) compound BaFe<sub>12</sub>O<sub>19</sub> is made possible by the fact that the charge disproportionation of Mn<sup>3+</sup> into Mn<sup>2+</sup> and Mn<sup>4+</sup> requires less energy than that of Fe<sup>3+</sup> into Fe<sup>2+</sup> and Fe<sup>4+</sup>, related to the smaller effective Coulomb interaction of Mn<sup>3+</sup> (d<sup>4</sup>) compared to Fe<sup>3+</sup> (d<sup>5</sup>). The different chemical environments determine the location of the differently charged ions: with Mn<sup>3+</sup> occupying positions with (distorted) octahedral local symmetry, Mn<sup>4+</sup> ions prefer octahedrally coordinated sites in order to optimize their covalent bonding. Larger and more ionic bonded Mn<sup>2+</sup> ions with a spherical charge distribution accumulate at tetrahedrally coordinated sites. Simulations of the experimental Mn-L<sub>2,3</sub> XAS spectra of two different samples with <i>x</i> = 1.5 and <i>x</i> = 1.7 led to Mn<sup>2+</sup>:Mn<sup>3+</sup>:Mn<sup>4+</sup> atomic ratios of 0.16:0.51:0.33 and 0.19:0.57:0.24
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