Theoretical Investigation of the Methanol Decomposition by Fe⁺ and Fe(C₂H₄)⁺: A π‑Type Ligand Effect

Density functional theory has been used to probe the mechanism of gas-phase methanol decomposition by bare Fe⁺ and ligated Fe­(C₂H₄)⁺ in both quartet and sextet states. For the Fe⁺/methanol system, Fe⁺ could directly attach to the O and methyl-H atoms of methanol, respectively, forming two encounter isomers. The methanol reaction with Fe⁺ prefers initial C–O bond activation to yield methyl with slight endothermicity, whereas CH₄ elimination is hindered by the strong endothermicity and high-energy barrier of hydroxyl-H shift. For the Fe­(C₂H₄)⁺/methanol system, the major product of H₂O is formed through six elementary steps: encounter complexation, C–O bond activation, C–C coupling, β-H shift, hydride H shift, and nonreactive dissociation. Both ligand exchange and initial C–O bond activation mechanisms could account for ethylene elimination with the ion products Fe­(CH₃OH)⁺ and (CH₃)­Fe­(OH)⁺, respectively. With the assistance of a π-type C₂H₄ ligand, the metal center in the Fe­(C₂H₄)⁺/CH₃OH system avoids formation of unfavorable multi-σ-type bonding and thus greatly enhances the reactivity compared to that of bare Fe⁺

Suppression Effect and Mechanism of Platinum and Nitrogen-Containing Silane on the Tracking and Erosion of Silicone Rubber for High-Voltage Insulation

How to effectively improve the tracking and erosion resistance of silicone rubber (SR) was an urgent topic in the field of high-voltage insulation. In this work, the tracking and erosion resistance of SR was significantly improved by incorporating platinum (Pt) catalyst and nitrogen-containing silane (NS). The suppression effect and mechanism of Pt/NS on tracking and erosion were studied by inclined plane (IP) test, thermogravimetry (TG), thermogravimetry-Fourier transform infrared spectrometry, laser Raman spectroscopy, and scanning electron microscopy. It revealed that when 1.4 phr of NS and 6.7 ppm of Pt were added, the tracking resistance of SR was improved from 2.5 to 4.5 kV level in the IP test, and the eroded mass was significantly reduced. This might be attributed to the synergistic effect of Pt/NS on silicone chains. At a high temperature produced by arc discharge, Pt/NS would catalyze radical cross-linking, meanwhile suppressing oxidation and depolymerization of silicone chains. Hence, a tightly cross-linked network was formed and protected inner materials from arc ablation. Moreover, carbon deposit during pyrolysis was suppressed by Pt/NS, which served as the secondary mechanism of tracking suppression

The correlation between Tc17 cells and Foxp3-expressing T cells in the patients of CIN and UCC tissues

<p>(r = 0.713, <i>P</i><0.001, n = 47).</p

The correlations between Tc17 cells and microvessel density (MVD).

<p>(A) Linear regression analysis between the levels of Tc17 cells and MVD (Total: r = 0.987, <i>P</i><0.0001, n = 65; control: r = 0.814, <i>P</i><0.001, n = 18, CIN: r = 0.923, <i>P</i><0.001, n = 17; UCC: r = 0.938, <i>P</i><0.0001, n = 30). MVD from each sample was plotted against Tc17 cells level from the same person. (B) Representative immunohistochemical staining of MVD in cervical tissues of three groups. Representative sites with low (100×, upper panels) and high (400×, lower panels) magnification were shown.</p

The correlations between Tc17 cells and Th17 cells.

<p>(a, b) Linear regression analysis between frequencies of Tc17 cell and Th17 cells in the blood (r_CIN = 0.435, <i>P</i> = 0.042, n = 22; r_UCC = 0.403, <i>P</i> = 0.016, n = 36). (c, d) Linear regression analysis between the levels of Tc17 cells and Th17 cells in the cervical tissues (r_CIN = 0.441, <i>P</i> = 0.039, n = 17; r_UCC = 0.693, <i>P</i> = 0.026, n = 30).</p

The levels of circulation Tc17 cells in representative controls, CIN patients and UCC patients.

<p>Upper right quadrants are the domains of Tc17 (CD8⁺ IL-17⁺) cells and the percentages of them were shown in each panel.</p

The frequency of Tc17 cells by immunohistochemical staining.

<p>(a) Compared to healthy controls (n = 30), significantly increased numbers of Tc17 cells were found in both tissues of UCC patients (<i>P</i> = 0.0007, n = 46) and CIN patients (<i>P</i> = 0.026, n = 28). Significant difference was also found between CIN and UCC tissues (<i>P</i> = 0.0086). (b) In tumor region, those UCC patients with lymph node metastases (n = 30) were detected significantly statistical higher Tc17 cells frequency than those patients without lymph node metastases (<i>P</i> = 0.035, n = 16). *<i>P</i><0.05, **<i>P</i><0.01, ****<i>P</i><0.001.</p

Clinical Characteristics of UCC Patients.

<p>Abbreviation: FIGO, International Federation of Gynecologists and Obstetricians; SCC, squamous cell carcinoma; ADC, adenocarcinoma; ADSC, adenosquamous carcinoma.</p

Expression of Tc17 cells in cervical tissues of the three groups.

<p>(A) Immunohistochemical double staining for Tc17 cells in the control group (a and d), CIN group (b and e) and UCC group (c and f). Representative sites with low (200×, upper panels) and high (400×, lower panels) magnification were shown. (B) IL-17-producing cells were stained red (in the cytoplasm) and CD8⁺ cells were stained black (in the membrane). The co-expression of CD8 and IL-17 confirmed that a proportion of Tc17 cells.</p

The frequency of Tc17 cells by flow cytometry.

<p>(a) Tc17 frequencies in the three groups. Significantly increased Tc17 cells were found in untreated UCC patients (<i>P</i> = 0.0076, n = 49) and CIN patients (<i>P</i> = 0.0149, n = 25) compared to healthy controls (n = 28). (b) Tc17 frequency in positive or negative lymph node metastases in UCC patients. Compared with patients without lymph node metastases (n = 15), significantly increased Tc17 frequency (<i>P</i> = 0.0026) was found in lymph node metastases patients (n = 35). Student's t test was used and bars represent SD, *<i>P</i><0.05, **<i>P</i><0.01.</p