A new method to synthesize very active and stable supported metal Pt catalysts: thermo-destabilization of microemulsions

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A new technique to deposit nanoparticles synthesized in reverse micellar microemulsions onto support material without agglomeration is named thermal destabilization of microemulsion. The multifaceted Pt crystals, mostly truncated octahedra, were produced inside reverse micelles with an average size of 2.5 nm and a narrow size distribution. After deposition, the Pt crystals were found to be well dispersed on the support with an average size of 2.5 nm. After testing with hydrogenation of α-methyl styrene, the produced Pt-catalyst showed higher activity (6 times higher) and stability than commercial ones. The advantages of this synthesis route of nanoparticles include simple operation, and the ease of controlling the size and shape of nanoparticles without using capping agents.DFG, EXC 314, Unifying Concepts in Catalysi

Overexpression of RRM2 decreases thrombspondin-1 and increases VEGF production in human cancer cells in vitro and in vivo: implication of RRM2 in angiogenesis

<p>Abstract</p> <p>Background</p> <p>In addition to its essential role in ribonucleotide reduction, ribonucleotide reductase (RNR) small subunit, RRM2, has been known to play a critical role in determining tumor malignancy. Overexpression of RRM2 significantly enhances the invasive and metastatic potential of tumor. Angiogenesis is critical to tumor malignancy; it plays an essential role in tumor growth and metastasis. It is important to investigate whether the angiogenic potential of tumor is affected by RRM2.</p> <p>Results</p> <p>We examined the expression of antiangiogenic thrombospondin-1 (TSP-1) and proangiogenic vascular endothelial growth factor (VEGF) in two RRM2-overexpressing KB cells: KB-M2-D and KB-HURs. We found that TSP-1 was significantly decreased in both KB-M2-D and KB-HURs cells compared to the parental KB and mock transfected KB-V. Simultaneously, RRM2-overexpressing KB cells showed increased production of VEGF mRNA and protein. In contrast, attenuating RRM2 expression via siRNA resulted in a significant increased TSP-1 expression in both KB and LNCaP cells; while the expression of VEGF by the two cells was significantly decreased under both normoxia and hypoxia. In comparison with KB-V, overexpression of RRM2 had no significant effect on proliferation in vitro, but it dramatically accelerated in vivo subcutaneous growth of KB-M2-D. KB-M2-D possessed more angiogenic potential than KB-V, as shown in vitro by its increased chemotaxis for endothelial cells and in vivo by the generation of more vascularized tumor xenografts.</p> <p>Conclusion</p> <p>These findings suggest a positive role of RRM2 in tumor angiogenesis and growth through regulation of the expression of TSP-1 and VEGF.</p

Creation of Brønsted acid sites on Sn-based solid catalysts for the conversion of biomass

Hydroxyl-attached Sn species are highly dispersed on the surface of mesoporous silica (SBA-15) by the grafting of dimethyldichlorostannane followed by calcination to transform the methyl groups into hydroxyl groups (S–Sn–OH). S–Sn–OH has both Lewis and Brønsted acidic sites, resulting in superior catalytic activities in the acetalisation of glycerol

Histone H2a mRNA interacts with Lin28 and contains a Lin28-dependent posttranscriptional regulatory element

Lin28 has been shown to block the processing of let-7 microRNAs implicated in the regulation of cell growth and differentiation. Here, we show that Lin28 also specifically associates with ribonucleoprotein particles containing the replication-dependent histone H2a mRNA in mouse embryonic stem cells. We further show that the coding region of H2a mRNA harbors high affinity binding sequences for Lin28 and that these sequences stimulate the expression of reporter genes in a Lin28-dependent manner. We suggest that a key function of Lin28 in the maintenance of pluripotency is to promote the expression of the H2a gene (and perhaps also other replication-dependent histone genes) at the posttranscriptional level in order to coordinate histone production with the unique proliferative properties of embryonic stem cells