CO2 hydrogenation over Fe-Co bimetallic catalysts with tunable selectivity through a graphene fencing approach.

Tuning CO2 hydrogenation product distribution to obtain high-selectivity target products is of great significance. However, due to the imprecise regulation of chain propagation and hydrogenation reactions, the oriented synthesis of a single product is challenging. Herein, we report an approach to controlling multiple sites with graphene fence engineering that enables direct conversion of CO2/H2 mixtures into different types of hydrocarbons. Fe-Co active sites on the graphene fence surface present 50.1% light olefin selectivity, while the spatial Fe-Co nanoparticles separated by graphene fences achieve liquefied petroleum gas of 43.6%. With the assistance of graphene fences, iron carbides and metallic cobalt can efficiently regulate C-C coupling and olefin secondary hydrogenation reactions to achieve product-selective switching between light olefins and liquefied petroleum gas. Furthermore, it also creates a precedent for CO2 direct hydrogenation to liquefied petroleum gas via a Fischer-Tropsch pathway with the highest space-time yields compared to other reported composite catalysts.

High-Precision 3D-DIC Measurement Method Based on Improved Forward Newton Iteration.

To solve the problems of the traditional 3D-DIC algorithm based on feature information or FFT search at the expense of accuracy in exchange for time, such as error-point extraction, mismatching of feature points, poor robustness, and accuracy loss caused by poor anti-noise performance, an improved high-precision 3D-DIC measurement method was proposed. In this method, the exact initial value is obtained by an exhaustive search. Then, the forward Newton iteration method is used for pixel classification, and the first-order nine-point interpolation is designed, which can quickly obtain the elements of Jacobian and Hazen matrix, and achieve accurate sub-pixel positioning. The experimental results show that the improved method has high accuracy, and its mean error and standard deviation stability and extreme value are better than similar algorithms. Compared with the traditional forward Newton method, the total iteration time of the improved forward Newton method is reduced in the subpixel iteration stage, and the computational efficiency is 3.8 times that of the traditional NR algorithm. The whole process of the proposed algorithm is simple and efficient, and it has application value in the precision occasions requiring high precision.

High-yield production of liquid fuels in CO2 hydrogenation on a zeolite-free Fe-based catalyst.

Catalytic conversion of CO2 to long-chain hydrocarbons with high activity and selectivity is appealing but hugely challenging. For conventional bifunctional catalysts with zeolite, poor coordination among catalytic activity, CO selectivity and target product selectivity often limit the long-chain hydrocarbon yield. Herein, we constructed a singly cobalt-modified iron-based catalyst achieving 57.8% C5+ selectivity at a CO2 conversion of 50.2%. The C5+ yield reaches 26.7%, which is a record-breaking value. Co promotes the reduction and strengthens the interaction between raw CO2 molecules and iron species. In addition to the carbide mechanism path, the existence of Co3Fe7 sites can also provide sufficient O-containing intermediate species (CO*, HCOO*, CO3 2*, and ) for subsequent chain propagation reaction via the oxygenate mechanism path. Reinforced cascade reactions between the reverse water gas shift (RWGS) reaction and chain propagation are achieved. The improved catalytic performance indicates that the KZFe-5.0Co catalyst could be an ideal candidate for industrial CO2 hydrogenation catalysts in the future.

Boosting the synthesis of value-added aromatics directly from syngas via a Cr2O3 and Ga doped zeolite capsule catalyst.

Even though the transformation of syngas into aromatics has been realized via a methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO2 coating was combined with the methanol synthesis catalyst Cr2O3 to boost the synthesis of value-added aromatics, especially para-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C-C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.

Selective Conversion of CO2 into para-Xylene over a ZnCr2 O4 -ZSM-5 Catalyst.

An oxide-zeolite (ZnCr2 O4 -ZSM-5) catalyst for directly converting CO2 to aromatics was designed and developed. It showed high PX/X (the C-mol ratio of p-xylene to all xylene) and PX/aromatics (the C-mol ratio of p-xylene to aromatics) ratios, which reached 97.3 and 63.9 %, respectively.

Direct and Oriented Conversion of CO2 into Value-Added Aromatics.

The oriented conversion of CO2 into target high-value chemicals is an effective way to reduce carbon emissions, but still presents a challenge. In this communication, we report the oriented conversion of CO2 into value-added aromatics, especially para-xylene, in a single pass by combining core-shell structured Zn-doped H-ZSM-5 (Zn-ZSM-5@SiO2 ) and a Cr2 O3 component. Through precise regulation of the acidity of Zn-ZSM-5@SiO2 , high para-xylene selectivity (38.7 % in the total products) at a CO2 conversion of 22.1 % was achieved. Furthermore, a CO2 -assisted effect in the synthesis of aromatics during the tandem process has been clarified through a control experiment. The CO2 reactant can act as a hydrogen acceptor to accelerate the dehydrogenation of alkenes, intermediates in the synthesis of aromatics, thereby increasing the driving force towards aromatics in the tandem reaction process.

Snail as a key regulator of PRL-3 gene in colorectal cancer.

The regulators of a key metastasis gene PRL-3 in colorectal cancer (CRC) are still largely unknown. We found three potential binding sites of Snail, a key transcriptional factor involved in the epithelial-mesenchymal transition (EMT), in the region of PRL-3 promoter (located at -642 to -383). Moreover, our results showed that one of the Snail binding sites (located at -624 to -619) was the key element to maintain promoter activity of human PRL-3 gene. The transcriptional activity of PRL-3 promoter was abolished after the Snail binding site (located at -624 to -619) was mutated. Both promoter activity and protein expression of PRL-3 in CRC cell lines could be regulated by Snail. In clinical samples of CRC and metastatic lymph node of CRC, expression of PRL-3 protein was correlated with expression of Snail protein. Functional studies using gene over-expression and knockdown methods indicated that Snail promoted proliferation, cell adhesion and migration of human CRC cells. In SW480 cells with PRL-3 stable knockdown, cell proliferation increased after Snail was up-regulated. Our data first reveal transcriptional factor Snail as a key regulator of PRL-3 in CRC. The link between Snail and PRL-3 suggests a new potential mechanism of Snail contributing to progression and metastasis of CRC.

Over-expression of CDH22 is associated with tumor progression in colorectal cancer.

CDH22, a member of the cadherins family, is highly expressed in the pituitary gland and the brain. It has been previously found that CDH22 is involved in morphogenesis and tissue formation in neural and non-neural cells of the brain and neuroendocrine organ. However, little is known about its role in colorectal cancer. Here the role of CDH22 in colorectal tumor was tested, and effects of inhibition of CDH22 expression on proliferation and metastasis were examined. We found that CDH22 was over-expressed at both transcriptional and translational levels in colorectal cancer and lymphatic metastasis of colorectal carcinoma, compared with normal colorectal mucosa. CDH22 over-expression was significantly associated with invasion and metastasis of colorectal cancer both at protein and mRNA levels. CDH22 knockdown partially blocked proliferation of colorectal cancer cells in vivo and in vitro. CDH22 knockdown was sufficient to attenuate invasion of colorectal cancer cells and inhibit tumor metastasis in a mouse model of colon surgical orthotopic implantation. Our results reveal for the first time a new role of CDH22 in progression of colorectal cancer.

PRL-3 promotes epithelial mesenchymal transition by regulating cadherin directly.

PRL-3 is a key gene associated with progression and metastasis of colorectal cancer. Recently PRL-3 was suggested to promote epithelial mesenchymal transition (EMT) by downregulating E-cadherin expression. But the mechanisms of EMT induced by PRL-3 remain largely unknown. Here we found that PRL-3 could also promote EMT in a colorectal cancer cell model SW480 with deficient E-cadherin expression in vivo and in vitro. PRL-3 stable overexpression or knockdown SW480 cells were injected subcutaneously into nude mice. Immunohistochemical analyses of tumor samples from nude mice showed that PRL-3 promoted upregulation of mesenchymal marker vimentin and downregulation of epithelial markers E-cadherin and cytokeratin. Glycogen synthase kinase-3beta inactivated by PRL-3 as assessed by phosphospecific antibodies was a key event in EMT induced by PRL-3. Inhibition of glycogen synthase kinase-3beta by lithium chloride, a highly selective inhibitor, leading to phosphorylation of glycogen synthase kinase-3beta increased Snail expression. In order to identify the direct effects of PRL-3, we isolated CDH22, one member of cadherin family, as a new candidate of interacting proteins of PRL-3 in yeast two-hybrid systems, and the interaction was confirmed in vitro by GST pull-down assay or in exogenous cell systems and endogenous colorectal cancer cells by co-immunoprecipitation assay and co-localization analysis. We observed that PRL-3 promoted downregulation of CDH22 expression. Interestingly, expression of E-cadherin was recovered in SW480 cells after PRL-3 was knocked-down. Our results first linked PRL-3 to cadherin directly. It provided new insights into the regulatory mechanisms of EMT induced by PRL-3.

[Expression of the zinc finger transcriptional factor Snail in colorectal carcinoma and its significance].

OBJECTIVE: To study expression of the zinc finger transcriptional factor Snail in colorectal carcinoma and its significance. METHODS: Expressions of Snail in colorectal carcinoma SW480 and SW620 cells were assayed by immunocytochemistry and immunofluorescent cytochemistry. The paraffin-embedded specimens from 68 cases of colorectal carcinoma and its corresponding adjacent tissues, 33 cases of adenoma and 35 cases of metastatic lymph nodes were also examined for Snail expressions using immunohistochemistry. RESULTS: Snail protein was located mainly in the cell nucleus of SW480 and SW620 cells. The expressions of PRL-3 protein in the specimens of colorectal carcinoma, normal mucosa, adenoma and metastatic lymph nodes were significantly different (Chi(2)=92.852, P=0.000). In the adenoma tissues, the expression was significantly higher than that in normal mucosa (Z=-2.902, P=0.004), the metastatic lymphnodes had significantly higher expressions than the primary colorectal carcinomas (Z=-4.951, P=0.000), which, in turn, showed significantly higher expression than the adenoma tissues (Z=-3.572, P=0.000). Significant correlation of Snail expression was found to the progression and metastasis of colorectal carcinoma (Z=-2.043, P=0.041). CONCLUSION: The expression of Snail is significantly correlated to genesis, progression and metastasis of colorectal carcinoma.