Effect of a plated Fe-Cr-Ni alloy layer for rapid nitriding of invar

The nitriding rate in a plated invar with an Fe-Ni-Cr alloy (face-centred cubic) layer were compared by optical microscopy with the rate in an unplated invar. In the plated invar rapid nitrogen diffusion was discovered. The plated layer plays a role in enhancing the nitriding rate. The result gives a solution for an abnormal enhancement nitriding rate in austenitic stainless steels. The enhancement is explained from the viewpoint of non-equilibrium thermodynamics.     

The "Swedish" mutation of the amyloid precursor protein (APPswe) dissociates components of object-location memory in aged Tg2576 mice.

Aged Tg2576 mice show abnormalities in hippocampal morphology and physiology and display behavioral deficits in spatial navigation tasks consonant with a deficit in the functional properties of the hippocampus. However, the nature of the spatial representations disrupted by the "Swedish" mutation of the amyloid precursor protein (APPswe) is unclear. In an effort to characterize the memory deficits in Tg2576 mice, the spontaneous object exploration paradigm was used to interrogate spatial and object memory in mice. With object arrays of comparable size, 16-month-old Tg2576 mice showed a normal object familiarity/novelty effect but impaired memory for the location of objects when 2 objects exchanged locations (topological transformation; Experiment 1). In contrast, Tg2576 mice showed preferential exploration of familiar objects when they were moved to previously unoccupied locations (Experiment 2), irrespective of whether the transformation altered the metric properties of the object array (Experiments 3). These results suggest that Tg2576 mice are able to form representations of the identity of objects and a memory of the spatial organization of objects in an arena. In contrast, conjunctive memory for specific object-location associations is severely impaired in aged Tg2576 mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of sintering on the corrosion behavior of a Ti‐6Al‐4V alloy

This work studies the influence of the sintering conditions of a Ti‐6Al‐4V alloy on its corrosion performance. The alloy was vacuum sintered in different conditions of time and temperature. The density and microstructure (designating phase distribution) are evaluated. Corrosion resistance through electrochemical techniques (EIS) in 2 N and 6 N hydrochloric acid solutions, and oxidation resistance at 900, 1000 and 1100°C are appraised, and corrosion is studied by microstructural and X‐ray diffraction.     

Altered Fatty Acid Metabolism-Related Gene Expression in Liver from Morbidly Obese Women with Non-Alcoholic Fatty Liver Disease

Lipid accumulation in the human liver seems to be a crucial mechanism in the pathogenesis and the progression of non-alcoholic fatty liver disease (NAFLD). We aimed to evaluate gene expression of different fatty acid (FA) metabolism-related genes in morbidly obese (MO) women with NAFLD. Liver expression of key genes related to de novo FA synthesis (LXRα, SREBP1c, ACC1, FAS), FA uptake and transport (PPARγ, CD36, FABP4), FA oxidation (PPARα), and inflammation (IL6, TNFα, CRP, PPARδ) were assessed by RT-qPCR in 127 MO women with normal liver histology (NL, n = 13), simple steatosis (SS, n = 47) and non-alcoholic steatohepatitis (NASH, n = 67). Liver FAS mRNA expression was significantly higher in MO NAFLD women with both SS and NASH compared to those with NL (p = 0.003, p = 0.010, respectively). Hepatic IL6 and TNFα mRNA expression was higher in NASH than in SS subjects (p = 0.033, p = 0.050, respectively). Interestingly, LXRα, ACC1 and FAS expression had an inverse relation with the grade of steatosis. These results were confirmed by western blot analysis. In conclusion, our results indicate that lipogenesis seems to be downregulated in advanced stages of SS, suggesting that, in this type of extreme obesity, the deregulation of the lipogenic pathway might be associated with the severity of steatosis.     

Encapsulation of magnetic nanoparticles in a pH-sensitive poly(4-vinyl pyridine) polymer: a step forward to a multi-responsive system

A multiresponsive system that consists on pH-responsive polymer microspheres with encapsulated iron oxide magnetic nanoparticles that rendered the core magnetic to enable externally controlled actuation under magnetic induction has been developed. The inorganic nanoparticles were first prepared and, then, further encapsulated in a pH-sensitive poly(4-vinylpyridine). These spheres have been obtained by a modification of the simple, rapid and high-reproducible nanoprecipitation method. Magnetic measurements showed that the iron oxide nanoparticles are superparamagnetic and, therefore, able to undergo a local increase of the temperature when an oscillating magnetic field is applied. Magnetically triggered heating and pH sensitivity can be useful for biomedical applications.     

Delivery of chemotropic proteins and improvement of dopaminergic neuron outgrowth through a thixotropic hybrid nano-gel

Chemotropic proteins guide neuronal projections to their final target during embryo development and are useful to guide axons of neurons used in transplantation therapies. Site-specific delivery of the proteins however is needed for their application in the brain to avoid degradation and pleiotropic affects. In the present study we report the use of Poly (ethylene glycol)-Silica (PEG-Si) nanocomposite gel with thixotropic properties that make it injectable and suitable for delivery of the chemotropic protein semaphorin 3A. PEG-Si gel forms a functional gradient of semaphorin that enhances axon outgrowth of dopaminergic neurons from rat embryos or differentiated from stem cells in culture. It is not cytotoxic and its properties allowed its injection into the striatum without inflammatory response in the short term. Long term implantation however led to an increase in macrophages and glial cells. The inflammatory response could have resulted from non-degraded silica particles, as observed in biodegradation assays.