The Correlation of Interfacial Interaction and Catalytic Performance of N‑Doped Mesoporous Carbon Supported Cobalt Nanoparticles for Fischer–Tropsch Synthesis

The interfacial interaction between active species and supports is of significance for the catalytic performance of heterogeneous catalysts. Accordingly, the N-doped mesoporous carbon (NMC) was employed to support cobalt nanoparticles for insight into the nature of interfacial interaction and the reactivity of Fischer–Tropsch synthesis (FTS). Through a series of characterization techniques, it is found that the nitrogen incorporated into the carbonaceous framework, especially the sp²-type nitrogen, eventually functions as heterogeneous sites for the nucleation and growth of cobalt species. Owing to the unique structure of NMC supports, a pronounced electron transfer from the NMC supports to cobalt oxide particles takes place at the interface. The solid-state interfacial interaction significantly affects the dispersion and reduction behavior of cobalt species on the NMC substrates, resulting in the shift of the reduction peak of small particles toward high temperature, which ultimately shapes an unusual catalytic feature in the FTS. The cobalt-specific activity experiences the transition from the increasing stage to the decreasing stage and the turnover frequency increases first and then levels off with the increase in particle size. The product selectivity is also found to shift toward light hydrocarbon for the NMC supported small cobalt particles

Restoration of miR-1228* Expression Suppresses Epithelial-Mesenchymal Transition in Gastric Cancer

<div><p>Dysregulated miRNAs play critical roles during carcinogenesis and cancer progression. In the present study, the function of miR-1228* in regulating cancer progression was investigated in gastric cancer. Decreased expression of miR-1228* was observed in human gastric cancer tissues comparing to normal tissues. Subsequently, the role of miR-1228* was evaluated <i>in vivo</i> using the tumor xenograft model. In this model, miR-1228* overexpression suppressed xenograft tumor formation. Furthermore, we demonstrated miR-1228* negatively regulated NF-κB activity in SGC-7901 gastric cancer cells and found that CK2A2 was a target of miR-1228*. Upregulation of miR-1228* decreased the expression of mesenchymal markers and increased the epithelial marker E-cadherin, suggesting its potential role in suppressing epithelial-mesenchymal transition. Collectively, these findings provide the first evidence that miR-1228* plays an important role in regulating gastric cancer growth and suggest that selective restoration of miR-1228* might be beneficial for gastric cancer therapy.</p> </div

Mechanistic Insight into the C₂ Hydrocarbons Formation from Syngas on fcc-Co(111) Surface: A DFT Study

A comprehensive density functional theory (DFT) calculation of C₂ hydrocarbons formation in Fischer–Tropsch synthesis (FTS) on the close-packed fcc-Co(111) surface has been carried out. The activation barriers and reaction energies for CO dissociation, CH_<i>x</i> hydrogenation, CH_<i>x</i> + CH_<i>y</i> coupling and C­(HO) insertion into CH_<i>x</i>, CH_<i>x</i>CH_<i>y</i>–O bond scission, and successive hydrogenation reactions involved in C₂ hydrocarbons formation have been examined, and the following conclusions could be concluded: (i) CH is the dominant monomer, which is formed via CO + H → CHO → CH + O; (ii) CHO insertion is more plausible for C–C chain formation compared with CO insertion and CH_<i>x</i>–CH_<i>y</i> coupling. The rate-determining steps for C₂ hydrocarbons are CO + H → CHO and CHCH + H → CH₂CH. Meanwhile, CH₃ hydrogenation to form CH₄ is more facile than C₂ hydrocarbons, which will lead to the low productivity and selectivity to C₂ hydrocarbons. (iii) Stepped-Co(111) surface has been modeled to clarify the role of defects during C₂ hydrocarbons formation, and the calculation results indicate that CHO and CH₂CH formation could be facilitated and CH₄ formation could be suppressed, suggesting that the step sites could effectively promote the catalytic activity and selectivity for C₂ hydrocarbons formation

NF-κB activation is responsible for the lower expression of miR-1228*.

<p>(A) Schematic representations of the miR-1228* promoter region (the black arrowheads is the c-Rel binding domains), the lower is the pGL3-miR-1228*-promoter construct. (B) 24 hours after transfection with pGL3-miR-1228*-promoter or pGL3-control, SGC-7901 cells were stimulated with or without TNF-α and/or PDTC for 8 hours, then relative luciferase activity was measured. The luciferase activity was normalized to Renilla luciferase activity expressed by pRL-TK and then compared with the relative luciferase level of pGL3-control. * <i>P</i> <0.05 as compared with control. ^#<i>P</i> <0.05 as compared with TNF-α-treated group. (C) SGC-7901 cells were co-transfected with pGL3-miR-1228*-promoter/pGL3-control and GFP-c-Rel/GFP-control, and the relative luciferase expression was detected 48 hours later. The luciferase activity was normalized to Renilla luciferase activity expressed by pRL-TK and then compared with the relative luciferase level of GFP-control. Data were expressed as means ± SEM, n  =  3.</p

Downregulation of miR-1228* in gastric cancer tissues and gastric cancer cell lines.

<p>(A) In human gastric cancer tissues compared with paired adjacent noncancerous (normal) gastric tissues, the miR-1228* was down-regulated. The expression of miR-1228* was analyzed by real-time PCR and normalized to RNU6B. The results are displayed on a log scale. The statistical differences between samples were analyzed with the wilcoxon signed-rank test (n = 50). (B) Relative expression of miR-1228* in 50 gastric cancer tissues compared with matched normal tissues. Data are shown as 2^-ΔΔCT values. (C) The expression of miR-1228* in 3 gastric cancer cell lines and one immortalized normal gastric mucosal epithelial cell line (GES-1) was carried out by real-time PCR and normalized to RNU6B. Results are means ± SEM, n  =  3.</p

Regulation of NF-κB activity and CK2A2 expression by miR-1228*.

<p>(A) SGC-7901-miR-1228* and SGC-7901-miR-NC were transfected with the NF-κB reporter construct, respectively. 48 hours after transfection, the luciferase activity was measured. The luciferase activity was normalized to Renilla luciferase activity. Results are means ± SEM, n  =  3. (B) Schematic graph of the putative binding site of miR-1228* in the CK2A2 predicted by miRanda. (C) Western blot analysis revealed that protein level of CK2A2 in miR-1228* stable overexpression SGC-7901 cells was significantly decreased compared with miR-NC. The level of GAPDH was used as a loading control. (D) miR-1228* significantly reduced the luciferase reading when co-transfected with pMIR-CK2A2 3’UTR plasmid, indicating interaction between miR-1228* and CK2A2 3’UTR at this site. The luciferase activity was normalized to Renilla luciferase activity expressed by pRL-TK. Data were expressed as means ± SEM, n  =  3.</p

Relationship between miR-1228* expression and clinicopathologic features of patients with gastric cancer (n = 50).

<p>Relationship between miR-1228* expression and clinicopathologic features of patients with gastric cancer (n = 50).</p

miR-1228* restoration inhibits xenograft tumor formation of gastric cancer cells.

<p>(A) miR-1228* was more than ten-fold changes in miR-1228* stable transfected SGC-7901 compared with NC. Results are means ± SEM, n  =  3. (B) Increased miR-1228* expression suppresses xenograft tumor growth. Stable transfection of SGC-7901 cells with miR-1228* or miR-NC were injected subcutaneously into nude mice. The volume of each tumor was measured twice each week. The average volume of tumors developed in nude mice is shown as means ± SEM, n  =  6 per treatment group. The statistical differences between samples were determined by the two-way ANOVA. (C) Compared with the control, the xenografts with miR-1228* overexpression were significantly smaller. The mice were sacrificed 5 weeks after inoculation. Two groups’ photograph of tumors is shown. (D) Tumors from each group were weighed immediately after removal. The tumor weight is indicated as means ± SEM, n  =  6.</p

Effect of miR-1228* on EMT in SGC-7901 cells.

<p>(A) Western blot analysis of epithelial marker (E-cadherin) and mesenchymal markers (Vimentin, β-catenin, Snail, Slug, and ZEB1/2) in miR-1228* stable transfected SGC-7901 cells and control. (B) Transwell migration assay showed that SGC-7901 cells stable transfected with miR-1228* had lower migratory potential in compare with miR-NC (×100). (C) The relative level of cell migration is presented as the mean ± SEM, based on three independent experiments. (D) Expression of EMT-related markers in xenograft tumor. Immunohistochemical staining indicated decreased Vimentin and increased E-cadherin expression in miR-1228* xenograft tumor compared to the control (×400).</p

Two-Stripper/Flash/Distillation Column System Design, Operation, and Control for Separating 2‑Pentanone/4-Heptanone/Water Azeotropic Mixture via Navigating Residue Curve Maps and Balancing Total Annual Cost and Product Loss

A novel method for the synergetic production of 2-pentanone and 4-heptanone has been explored recently at the Institute of Coal Chemistry, Chinese Academy of Sciences (ICC, CAS). The collected mixture, containing mainly 2-pentanone/4-heptanone/water/carbon dioxide, presents heterogeneous azeotropes. The separation of this quaternary mixture is the main problem urgently to be effectively solved. In this work, a two-stripper/flash/column flow sheet is proposed to achieve the separation, in which the heterogeneity of the system is fully utilized by using an overhead vapor–liquid–liquid (VLL) flash. A general total annual cost (GTAC) for balancing total annual cost (TAC) and product loss (PL) is proposed as an optimization function, and several optimization sequences are presented to facilitate the optimization. Four candidate sequences (S1, S2, S3, and S4) are derived from <i>navigating</i> the ternary and residue curve maps, of which the S4 cuts the GTAC with a marked margin (83.9%) compared with the S1. The rigorous economic design and optimum operation of the flow sheet are further investigated in detail. Moreover, several control structures (TCS1, TCS2, and DTCS, CTCS, C&TCS) are successively explored with consideration of ordinary-purity and high-purity separations. Dynamic control shows that whereas the flow sheet can be controlled by controlling one tray temperature in each stripper/column for ordinary-purity separation, an expensive and high-maintenance online composition control should be considered for high-purity separation