546 research outputs found
Short-range Charge and Spin Superstructures in Doped Layered Co Perovskites
We have investigated cobaltite relatives of the layered perovskite cuprates
and nickelates, PrCaCoO () and
LaSrCoO (), using elastic neutron scattering. We have
discovered doping-dependent incommensurate short-range ordering of charges and
magnetic moments, which in cobaltites occur in the range of heavy doping, . The charge order exists already at room temperature
and shows no change on cooling. The incommensurability of its propagation
vector, , roughly scales with the concentration
of Co ions, . Magnetic order is only established
at low T K and has twice larger periodicity, indicating a dominant
antiferromagnetic correlation between the nearest Co spins.Comment: 4 pages 4 figure
Effects of curcumin in an orthotopic murine bladder tumor model
Cigarette smoking (CS) is the main risk factor for bladder cancer development. There are more than 100 carcinogens present in cigarette smoke. Among the potential mediators of CS-induced alterations is nuclear factor-kappa (NF-κB), which is responsible for the transcription of genes related to cell transformation, tumor promotion, angiogenesis, invasion and metastasis. Curcumin is a polyphenol compound derived from Curcuma longa that suppress cellular transformation, proliferation, invasion, angiogenesis, and metastasis by down regulating NF-κB and its regulated genes. The aim of our study was to assess the effects of curcumin in bladder urothelial carcinoma. We studied the effects of curcumin in vitro and in vivo using the orthotropic syngeneic bladder tumor animal model MB49. Curcumin promotes apoptosis of bladder tumor cells in vitro. In vivo tumors of animals treated with curcumin were significantly smaller as compared to controls. Using immunohistochemistry, we demonstrated a decrease in the expression of Cox-2 by 8% and Cyclin D1 by 13% in the animals treated with curcumin; both genes regulated by NF-κB and related to cell proliferation. In this study, we showed that curcumin acts in bladder urothelial cancer, possibly dowregulating NF-κB-related genes, and could be an option in the treatment of urothelial neoplasms. The results of our study suggest that further research is warranted to confirm our findings
Polymer brushes in solid-state nanopores form an impenetrable entropic barrier for proteins
Polymer brushes are widely used to prevent the adsorption of proteins, but the mechanisms by which they operate have remained heavily debated for many decades. We show conclusive evidence that a polymer brush can be a remarkably strong kinetic barrier towards proteins by using poly(ethylene glycol) grafted to the sidewalls of pores in 30 nm thin gold films. Despite consisting of about 90% water, the free coils seal apertures up to 100 nm entirely with respect to serum protein translocation, as monitored label-free through the plasmonic activity of the nanopores. The conclusions are further supported by atomic force microscopy and fluorescence microscopy. A theoretical model indicates that the brush undergoes a morphology transition to a sealing state when the ratio between the extension and the radius of curvature is approximately 0.8. The brush-sealed pores represent a new type of ultrathin filter with potential applications in bioanalytical systems
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