Understanding Mechanical Response of Elastomeric Graphene Networks

Ultra-light porous networks based on nano-carbon materials (such as graphene or carbon nanotubes) have attracted increasing interest owing to their applications in wide fields from bioengineering to electrochemical devices. However, it is often difficult to translate the properties of nanomaterials to bulk three-dimensional networks with a control of their mechanical properties. In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features. The porous networks made of large reduced graphene oxide flakes (>20 μm) are superelastic and exhibit high energy absorption, showing much enhanced mechanical properties than those with small flakes (<2 μm). A better restoration of the graphitic nature also has a considerable effect. In comparison, microstructural differences, such as the foam architecture or the cell size have smaller or negligible effect on the mechanical response. The recoverability and energy adsorption depend on density with the latter exhibiting a minimum due to the interplay between wall fracture and friction during deformation. These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls

Printing in three dimensions with graphene

Responsive graphene oxide sheets form non‐covalent networks with optimum rheological properties for 3D printing. These networks have shear thinning behavior and sufficiently high elastic shear modulus (G′) to build self‐supporting 3D structures by direct write assembly. Drying and thermal reduction leads to ultra‐light graphene‐only structures with restored conductivity and elastomeric behavior

Graphene Oxide: An All-in-One Processing Additive for 3D Printing

Many 3D printing technologies are based on the development of inks and pastes to build objects through droplet or filament deposition (the latter also known as continuous extrusion, robocasting, or direct ink writing). Controlling and tuning rheological behavior is key for successful manufacturing using these techniques. Different formulations have been proposed, but the search continues for approaches that are clean, flexible, robust and that can be adapted to a wide range of materials. Here, we show how graphene oxide (GO) enables the formulation of water-based pastes to print a wide variety of materials (polymers, ceramics, and steel) using robocasting. This work combines flow and oscillatory rheology to provide further insights into the rheological behavior of suspensions combining GO with other materials. Graphene oxide can be used to manipulate the viscoelastic response, enabling the formulation of pastes with excellent printing behavior that combine shear thinning flow and a fast recovery of their elastic properties. These inks do not contain other additives, only GO and the material of interest. As a proof of concept, we demonstrate the 3D printing of additive-free graphene oxide structures as well as polymers, ceramics, and steel. Due to its amphiphilic nature and 2D structure, graphene oxide plays multiple roles, behaving as a dispersant, viscosifier, and binder. It stabilizes suspensions of different powders, modifies the flow and viscoelasticity of materials with different chemistries, particle sizes and shapes, and binds the particles together, providing green strength for manual handling. This approach enables printing complex 3D ceramic structures using robocasting with similar properties to alternative formulations, thus demonstrating the potential of using 2D colloids in materials manufacturing

SiC porous structures obtained with innovative shaping technologies

SiC structures with porosities ranging between 20–60% have been fabricated using two methods emulsification and freeze casting. While emulsification results in foam-like isotropic materials with interconnected pores, freeze casting can be used to fabricate highly anisotropic materials with characteristic layered architectures. The parameters that control the pore size and final porosity have been identified (solid content in the initial suspensions, emulsification times or speed of the freezing front). We have found that liquid state sintering (suing Al2O3 and Y2O3 as additives) at 1800 °C on a powder (SiC/Al2O3) bed provides optimum consolidation for the porous structures. The mechanical strength of the materials depends on their density. Freeze casted materials fabricated with bimodal particle size distributions (a controlled mixture of micro and nanoparticles) exhibit higher compressive strengths that can reach values of up to 280 MPa for materials with densities of 0.47

RM en el diagnóstico y control evolutivo de la degeneración combinada subaguda. A propósito de un caso

A deficit of vitamin B12, generally resulting from pernicious anaemia, can give rise to disorders of the spinal cord, brain, optic and peripheral nerves. The principal neurological syndrome is subacute combined degeneration of the spinal cord (SCD), which can cause progressive motor and/or sensitive alterations, instability and incontinency, due to the demyelination of the posterior horn of the spinal cord. The identification by magnetic resonance (MR) of signal hyperintensity in T2 weighted sequences at the level of the posterior horns of the spinal and/or cervical cord can be of great use in diagnosising the patient with SCD, above all when the symptoms are mild or nonspecific, and the patient does not have haematological or gastrointestinal alterations. Besides, the evolution of the altered signal of the posterior horns in MR can be of use in evaluating the efficacy of treatment, since their normalization is related to clinical improvemen

BDNF and NGF Signalling in Early Phases of Psychosis: Relationship with Inflammation and Response to Antipsychotics after 1 Year

Previous studies have indicated systemic deregulation of the proinflammatory or anti-inflammatory balance in individuals with first-episode psychosis (FEP) that persists 12 months later. To identify potential risk/protective factors and associations with symptom severity, we assessed possible changes in plasma levels of neurotrophins (brain-derived neurotrophic factor BDNF] and nerve growth factor NGF]) and their receptors in peripheral blood mononuclear cells (PBMCs). Expression of the 2 forms of BDNF receptors (active TrkB-FL and inactiveTrkB-T1) in PBMCs of FEP patients changed over time, TrkB-FL expression increasing by 1 year after diagnosis, while TrkB-T1 expression decreased. The TrkB-FL/TrkB-T1 ratio (hereafter FL/T1 ratio) increased during follow-up in the nonaffective psychosis group only, suggesting different underlying pathophysiological mechanisms in subgroups of FEP patients. Further, the expression of the main NGF receptor, TrkA, generally increased in patients at follow-up. After adjusting for potential confounders, baseline levels of inducible isoforms of nitric oxide synthase, cyclooxygenase, and nuclear transcription factor were significantly associated with the FL/T1 ratio, suggesting that more inflammation is associated with higher values of this ratio. Interestingly, the FL/T1 ratio might have a role as a predictor of functioning, a regression model of functioning at 1 year suggesting that the effect of the FL/T1 ratio at baseline on functioning at 1 year depended on whether patients were treated with antipsychotics. These findings may have translational relevance; specifically, it might be useful to assess the expression of TrkB receptor isoforms before initiating antipsychotic treatment in FEPs

BDNF and NGF signalling in early phases of psychosis: relationship with inflammation and response to antipsychotics after a 1 year

Previous studies have indicated systemic deregulation of the proinflammatory or anti-inflammatory balance in individuals with first-episode psychosis (FEP) that persists 12 months later. To identify potential risk/protective factors and associations with symptom severity, we assessed possible changes in plasma levels of neurotrophins (brain-derived neurotrophic factor [BDNF] and nerve growth factor [NGF]) and their receptors in peripheral blood mononuclear cells (PBMCs). Expression of the 2 forms of BDNF receptors (active TrkB-FL and inactiveTrkB-T1) in PBMCs of FEP patients changed over time, TrkB-FL expression increasing by 1 year after diagnosis, while TrkB-T1 expression decreased. The TrkB-FL/TrkB-T1 ratio (hereafter FL/T1 ratio) increased during follow-up in the nonaffective psychosis group only, suggesting different underlying pathophysiological mechanisms in subgroups of FEP patients. Further, the expression of the main NGF receptor, TrkA, generally increased in patients at follow-up. After adjusting for potential confounders, baseline levels of inducible isoforms of nitric oxide synthase, cyclooxygenase, and nuclear transcription factor were significantly associated with the FL/T1 ratio, suggesting that more inflammation is associated with higher values of this ratio. Interestingly, the FL/T1 ratio might have a role as a predictor of functioning, a regression model of functioning at 1 year suggesting that the effect of the FL/T1 ratio at baseline on functioning at 1 year depended on whether patients were treated with antipsychotics. These findings may have translational relevance; specifically, it might be useful to assess the expression of TrkB receptor isoforms before initiating antipsychotic treatment in FEP

Pro-/antiinflammatory dysregulation in early psychosis: Results from a 1-year follow-Up study

Background: Previous studies indicated a systemic deregulation of the pro-/antiinflammatory balance in subjects after 6 months of a first psychotic episode. This disruption was reexamined 12 months after diagnosis to identify potential risk/ protective factors and associations with symptom severity. Methods: Eighty-five subjects were followed during 12 months and the determination of the same pro-/antiinflammatory mediators was carried out in plasma and peripheral blood mononuclear cells. Multivariate logistic regression analyses were used to identify risk/protective factors. Multiple linear regression models were performed to detect the change of each biological marker during follow-up in relation to clinical characteristics and confounding factors. Results: This study suggests a more severe systemic pro-/antiinflammatory deregulation than in earlier pathological stages in first psychotic episode, because not only were intracellular components of the inflammatory response increased but also the majority of soluble elements. Nitrite plasma levels and cyclooxygenase-2 expression in peripheral blood mononuclear cells are reliable potential risk factors and 15d-prostaglandin-J2 plasma levels a protection biomarker. An interesting relationship exists between antipsychotic dose and the levels of prostaglandin-E2 (inverse) and 15d-prostaglandin-J2 (direct). An inverse relationship between the Global Assessment of Functioning scale and lipid peroxidation is also present. Conclusions: Summing up, pro-/antiinflammatory mediators can be used as risk/protection biomarkers. The inverse association between oxidative/nitrosative damage and the Global Assessment of Functioning scale, and the possibility that one of the targets of antipsychotics could be the restoration of the pro-/antiinflammatory balance support the use of antiinflammatory drugs as coadjuvant to antipsychotics

Impact of renal retransplantation on graft and recipient survival

The aim of this study was to evaluate the influence of retransplantation in graft and recipient survival. METHODS: We carried out a retrospective study in 419 renal transplants and studied the influence of retransplantation in graft and patient survival. A homogeneity study was performed between the two groups with a Student`s T and a chi-square tests. Graft survival analysis was performed with Kaplan-Meyer and log rank tests. RESULTS: Of 419 transplants, 370 (88.3%) were first transplantations, 45 (10.7%) second transplantations and 4(1%) third ones. Mean follow-up of the whole group was 72.5 months (+/-54.1 SD). There were no differences in follow-up between groups (Mean Follow-up 73.1 months +/-54.4 SD in first transplantations vs. 61.6 months +/-51.2 SD in repeat transplantation. p >0.05). The actuarial graft survival showed no differences between patients with first transplantation and those with a repeat one. [3 and 5 year SV of 89% (95% CI: 87-91%) and 84%(95% CI: 82-86%) Vs 88% (95% CI; 83-93%) and 85% (95% CI:i; 80-90%) respectively]. After adjusting for all the heterogeneity variables we still did not find differences on graft survival. The actuarial recipient survival showed no differences between patients with first transplantation and those with a repeat one. [3 and 5 year SV of 98% and 96% Vs.97%]. CONCLUSIONS: There are no differences of graft and recipient survival between patients with a first transplantation and those with a repeat one

Smoking cessation improves clinical outcome in severe mental disorders and is modulated by genetic variability at CHRNA5 gene

Smoking has been traditionally tolerated for patients with mental disorders due to its hypothesized self-medication function (Schroeder and Morris, 2010).[...