Increased IGFBP2 Levels by Placenta-Derived Mesenchymal Stem Cells Enhance Glucose Metabolism in a TAA-Injured Rat Model via AMPK Signaling Pathway.

The insulin resistance caused by impaired glucose metabolism induces ovarian dysfunction due to the central importance of glucose as a source of energy. However, the research on glucose metabolism in the ovaries is still lacking. The objectives of this study were to analyze the effect of PD-MSCs on glucose metabolism through IGFBP2-AMPK signaling and to investigate the correlation between glucose metabolism and ovarian function. Thioacetamide (TAA) was used to construct a rat injury model. PD-MSCs were transplanted into the tail vein (2 × 106) 8 weeks after the experiment started. The expression of the IGFBP2 gene and glucose metabolism factors (e.g., AMPK, GLUT4) was significantly increased in the PD-MSC group compared to the nontransplantation (NTx) group (* p < 0.05). The levels of follicular development markers and the sex hormones AMH, FSH, and E2 were also higher than those in the TAA group. Using ex vivo cocultivation, the mRNA and protein expression of IGFBP2, AMPK, and GLUT4 were significantly increased in the cocultivation with the PD-MSCs group and the recombinant protein-treated group (* p < 0.05). These findings suggest that the increased IGFBP2 levels by PD-MSCs play an important role in glucose metabolism and ovarian function through the IGFBP2-AMPK signaling pathway.

Promotional effect of antimony on the selective catalytic reduction NO with NH3 over V-Sb/Ti catalyst.

The effect of antimony on the selective catalytic reduction (SCR) performance and SO2 durability of V-Sb/Ti was investigated. The physicochemical characteristics of catalyst were characterized by various techniques, including Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), NH3/SO2-temperature programmed desorption (TPD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs), X-ray photoelectron spectroscopy (XPS), and H2-temperature programmed reduction (H2-TPR). The V-Sb/Ti catalyst showed excellent activity in the range 200-300°C (compared with V/Ti), with an optimum achieved for 2 wt.% antimony. The total amount of acidic sites and NH3 adsorption characteristics did not affect the catalytic efficiency. The Sb5+ fraction was highest for V-2.0Sb/Ti and exhibited a positive correlation with the V4+ fraction. This phenomenon is related to the effect of synergistic between vanadium and antimony, promoting the conversion of V5+ to V4+ by Sb5+. Increasing the V4+ fraction in V-Sb/Ti increased the catalytic activity, which was mainly attributed to enhanced catalyst re-oxidation capability due to the addition of antimony. Furthermore, the addition of antimony delayed the adsorption of SO2 onto the V-Sb/Ti catalyst surface, improving the resistance to this gas. Therefore, the addition of antimony to V/Ti improved NOx conversion and SO2 durability.

Influence of the addition of vanadium to Pt/TiO2 catalyst on the selective catalytic oxidation of NH3 to N2.

In this work, the effect of the addition of vanadium to the Pt/TiO2 catalyst on the selective catalytic oxidation (SCO) of NH3 to N2 was investigated. It was found that the addition of vanadium significantly enhanced catalytic activity at all tested temperatures. The Pt/V/TiO2 catalyst exhibited the highest NH3 conversion (∼100%) and NH3 to N2 conversion (∼81%) at 250°C. The physicochemical characteristics of the catalysts were investigated via Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), NH3 temperature-programmed desorption (TPD), NH3 temperature-programmed oxidation (TPO), and in situ Fourier-transform infrared (FTIR) spectroscopy. It was found that the addition of V to the catalyst enhanced the conversion of NH3 as a result of the formation of new acid sites. The increase in the number of acid sites resulted in increased NH3 to N2 conversion via the internal selective catalytic reduction (i-SCR) mechanism. This mechanism involves the SCR of NOx, which are formed by the oxidation of NH3. Based on experimental results and analyses of the catalysts modified by the addition of V, it was shown that there was a close relation between reaction selectivity and the surface oxygen species of the catalyst and N2 yield. Furthermore, the addition of V increased the durability of SO2 by inhibiting the formation of ammonium bisulfate (ABS).

Influence of Mn valence state and characteristic of TiO2 on the performance of Mn-Ti catalysts in ozone decomposition.

The effects of physicochemical properties of Mn-Ti catalysts on O3 conversion were examined. The catalysts were prepared by a wet impregnation method that gave manganese supported on various commercial sources of TiO2. The properties of the catalysts were studied using physicochemical techniques, including Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA). The O3 decomposition tests of Mn-Ti catalysts with various manganese loadings revealed that the 10 wt% manganese catalyst exhibited optimal, excellent activity. The O3 conversion and Mn valence state of the Mn-Ti catalysts were different, depending on the structure of the TiO2 source. Increasing the O/Ti surface atomic ratio in TiO2 increased the Mn3+ ratio. The Mn3+ ratio directly affected the O3 decomposition activity of the Mn-Ti catalyst. When the Mn3+ ratio was the largest, the catalyst showed the highest activity in O3 decomposition. The valence state of Mn exposed to the surface was a critical factor in O3 decomposition by Mn-Ti catalysts.

Effect of the Mn oxidation state and lattice oxygen in Mn-based TiO2 catalysts on the low-temperature selective catalytic reduction of NO by NH3.

UNLABELLED: TiO2-supported manganese oxide catalysts formed using different calcination temperatures were prepared by using the wet-impregnation method and were investigated for their activity in the low-temperature selective catalytic reduction (SCR) of NO by NH3 with respect to the Mn valence and lattice oxygen behavior. The surface and bulk properties of these catalysts were examined using Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD). Catalysts prepared using lower calcination temperatures, which contained Mn4+ displayed high SCR activity at low temperatures and possessed several acid sites and active oxygen. The TPD analysis determined that the Brönsted and Lewis acid sites in the Mn/TiO2 catalysts were important for the low-temperature SCR at 80-160 and 200-350 degrees C, respectively. In addition, the available lattice oxygen was important for attaining high NO to NO2 oxidation at low temperatures. IMPLICATIONS: Recently, various Mn catalysts have been evaluated as SCR catalysts. However, there have been no studies on the relationship of adsorption and desorption properties and behavior of lattice oxygen according to the valence state for manganese oxides (MnO(x)). Therefore, in this study, the catalysts were prepared by the wet-impregnation method at different calcination temperatures in order to show the difference of manganese oxidation state. These catalysts were then characterized using various physicochemical techniques, including BET, XRD, TPR, and TPD, to understand the structure, oxidation state, redox properties, and adsorption and desorption properties of the Mn/TiO2 catalysts.

A study on the reaction characteristics of vanadium-impregnated natural manganese oxide in ammonia selective catalytic reduction.

This study investigated the effect of adding vanadium (V) to natural manganese oxide (NMO) in ammonia (NH3) selective catalytic reduction (SCR). The addition of V to NMO decreased the catalytic activity at low temperatures by blocking the active site. However, the enhancement of catalytic activity was achieved by controlling NH3 oxidation at high temperatures. From the NH3 temperature programmed desorption and oxygen on/off test, it was confirmed that the amount of Lewis acid site and active lattice oxygen of the catalyst affects the catalytic performance at low temperature.