The effect of vanadium alloying on the wear resistance of pearlitic rails

Due to the increasing demand on pearlitic rails to support heavier loads and higher speeds, grooved rails for tramways and light rail transit (LRT) require strengthening via alloying or heat treatment, i.e. accelerated cooling after hot-rolling. In this study, the wear performance of five different commercial grades is compared using unlubricated twin-disc testing and detailed microstructural characterisation. Results indicate that the vanadium-alloyed steel experiences less than half the wear rate of a heat-treated grade with a similar hardness. This is attributed to the increased stability and toughness of vanadium-containing cementite, as compared to pure cementite. The evidence suggests that vanadium partitions into the cementite lamellae during the formation of pearlite. This improvement in wear resistance due to vanadium could enable an approximately two-fold reduction in the maintenance and life cycle costs relative to heat-treated rail alternatives.regarded as transition-phases relative to mixtures of cementite and ferrite.ArcelorMittal Research Collaboration Agreement number 6085701156

Cuban Land Use and Conservation, from Rainforests to Coral Reefs

Cuba is an ecological rarity in Latin America and the Caribbean. Its complex political and economic history shows limited disturbances, extinctions, pollution, and resource depletion by legal or de facto measures. Vast mangroves, wetlands, and forests play key roles in protecting biodiversity and reducing risks of hazards caused or aggravated by climate change. Cuba boasts coral reefs with some of the region’s greatest fish biomass and coral cover. Although Cuba has set aside major protected areas that safeguard a host of endemic species, its environment is by no means pristine. Its early history is one of deforestation and agricultural production for colonial and neo-colonial powers. Using remote sensing, we find Cuba’s land today is 45% devoted to agricultural, pasturage, and crop production. Roughly 77% of Cuba’s potential mangrove zone is presently in mangrove cover, much outside legal protection; this is likely the most intact Caribbean mangrove ecosystem and an important resource for coastal protection, fish nurseries, and wildlife habitat. Even the largest watersheds with the most agricultural land uses have a strong presence of forests, mangroves, and wetlands to buffer and filter runoff. This landscape could change with Cuba’s gradual reopening to foreign investment and growing popularity among tourists—trends that have devastated natural ecosystems throughout the Caribbean. Cuba is uniquely positioned to avoid and reverse ecosystem collapse if discontinuities between geopolitical and ecosystem functional units are be addressed, if protection and conservation of endemic species and ecosystems services accompany new development, and if a sound ecological restoration plan is enacted

Caveolin-1 is a risk factor for postsurgery metastasis in preclinical melanoma models

Melanomas are highly lethal skin tumours that are frequently treated by surgical resection. However, the efficacy of such procedures is often limited by tumour recurrence and metastasis. Caveolin-1 (CAV1) has been attributed roles as a tumour suppressor, although in late-stage tumours, its presence is associated with enhanced metastasis. The expression of this protein in human melanoma development and particularly how the presence of CAV1 affects metastasis after surgery has not been defined. CAV1 expression in human melanocytes and melanomas increases with disease progression and is highest in metastatic melanomas. The effect of increased CAV1 expression can then be evaluated using B16F10 murine melanoma cells injected into syngenic immunocompetent C57BL/6 mice or human A375 melanoma cells injected into immunodeficient B6Rag1−/− mice. Augmented CAV1 expression suppresses tumour formation upon a subcutaneous injection, but enhances lung metastasis of cells injected into the tail vein in both models. A procedure was initially developed using B16F10 melanoma cells in C57BL/6 mice to mimic better the situation in patients undergoing surgery. Subcutaneous tumours of a defined size were removed surgically and local tumour recurrence and lung metastasis were evaluated after another 14 days. In this postsurgery setting, CAV1 presence in B16F10 melanomas favoured metastasis to the lung, although tumour suppression at the initial site was still evident. Similar results were obtained when evaluating A375 cells in B6Rag1−/− mice. These results implicate CAV1 expression in melanomas as a marker of poor prognosis for patients undergoing surgery as CAV1 expression promotes experimental lung metastasis in two different preclinical models

Magnetically recoverable photocatalysts based on metal oxide nanostructures (Fe and Zn)

The synthesis of y-Fe203&ZnO hybrid nanocomposites has been carried out by a solvothermal process at low temperature evaluating the influence of different experimental parameters and conditions. Several techniques such as X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (HR-TEM), Vibrating Sample Magnetometry (VSM), Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Dynamic Light Dispersion (DLS), Thermogravimetric Analysis (TGA) and UV-Vis Spectroscopy have been used to characterize the size, shape, structure, chemical composition, purity, crystalline phase and spectroscopic, magnetic, and finally the photocatalytic properties of nanocomposites prepared. Based on the results obtained, under irradiation ofUV-Vis light, the nanocomposites of y-Fe203-ZnO synthesised both at 6 hand 12 hat 120°C demonstrate a high photocatalytic activity (PCA) compared to pure y-Fe203 and ZnO samples for the degradation of methylene blue (MB), used as a cationic dye model. The percentage of degradation obtained for both cases was much higher than that obtained for the pure compounds of y-Fe203 and ZnO (85% and 81% vs 51% and 46%, respectively). Also, the study of stability, magnetic recovery and recyclability in MB dye degradation was carried out. For this purpose, photocatalytic tests were performed by reusing these hybrid nanocomposites during successive cycles. It has been verified that the PCA of these nanocomposites is maintained after several cicles of experiments with new MB solutions demonstrating their high photocatalytic stability. In conclusion, y-Fe203-ZnO hybrid nanostructures are a suitable candidate for its use in environmental applications, and to solve problems of removal of organic contaminants in the wastewater treatments as a magnetically recoverable photocatalyst

Optical binding-driven micropatterning and photosculpting with silver nanorods

Controlling the nano- and micropatterning of metal structures is an important requirement for various technological applications in photonics and biosensing. This work presents a method for controllably creating silver micropatterns by laser-induced photosculpting. Photosculpting is driven by plasmonic interactions between pulsed laser radiation and silver nanorods (AgNRs) in aqueous suspension; this process leads to optical binding forces transporting the AgNRs in the surroundings, while electronic thermalization results in photooxidation, melting, and ripening of the AgNRs into well-defined 3D structures. This work call these structures Airy castles due to their structural similarity with a diffraction-limited Airy disk. The photosculpted Airy castles contain emissive Ag nanoclusters, allowing for the visualization and examination of the aggregation process using luminescence microscopy. This work comprehensively examines the factors that define the photosculpting process, namely, the concentration and shape of the AgNRs, as well as the energy, power, and repetition rate of the laser. Finally, this work investigates the potential applications by measuring the metal-enhanced luminescence of a europium-based luminophore using Airy castles

The Caveolin-1 Connection to Cell Death and Survival

Nunez, S (Nunez, S.)[ 1,4 ] 1. Fac Med, CEMC, Lab Comunicac Celulares, Santiago, Chile. 4. Univ Talca, Fac Hlth Sci, Talca, ChileCaveolins are a family of membrane proteins required for the formation of small plasma membrane invaginations called caveolae that are implicated in cellular trafficking processes. In addition to this structural role, these scaffolding proteins modulate numerous intracellular signaling pathways; often via direct interaction with specific binding partners. Caveolin-1 is particularly well-studied in this respect and has been attributed a large variety of functions. Thus, Caveolin-1 also represents the best-characterized isoform of this family with respect to its participation in cancer. Rather strikingly, available evidence indicates that Caveolin-1 belongs to a select group of proteins that function, depending on the cellular settings, both as tumor suppressor and promoter of cellular traits commonly associated with enhanced malignant behavior, such as metastasis and multi-drug resistance. The mechanisms underlying such ambiguity in Caveolin-1 function constitute an area of great interest. Here, we will focus on discussing how Caveolin-1 modulates cell death and survival pathways and how this may contribute to a better understanding of the ambiguous role this protein plays in cancer