Metal–metal oxide nanostructure supported on graphene oxide as a multifunctional electro-catalyst for simultaneous detection of hydrazine and hydroxylamine

A ruthenium/iridium/iridium oxide nanohybrid supported on graphene oxide (RuIrOx_GO) was prepared via a new protocol. The activity of the nanohybrid towards the simultaneous detection of hydrazine (HY) and hydroxylamine (HA) was evaluated in phosphate-buffered saline solution (pH 7.0). Differential pulse voltammetry was used for the measurements, with a pulse amplitude of 50 mV and a scan rate of 0.04 V s−1. Using the modified electrode, the oxidation peak potentials for HY and HA can be easily distinguished, with a large peak separation of 0.36 V. Very low LOD values of 2.1 μM and 1.6 μM were found for HY and HA, respectively. The selectivity of the electrode and its stability were also studied The tolerance limits in the presence of different interfering compounds were evaluated. After five weeks, a deviation from the expected results of ~2% was observed for both HA and HY determinations. Keywords: Ir and Ru active phases, New synthesis protocol, Hydrazine, Hydroxylamine, Low detection limi

Active and stable graphene supporting trimetallic alloy-based electrocatalyst for hydrogen evolution by seawater splitting

The hydrogen evolution reaction (HER), adopting seawater as an electrolyte solution, is a promising and more sustainable alternative for the production of hydrogen, yet requiring more economic, highly efficient and stable electrocatalysts than the current ones. Herein, the synthesis of a Ni, Ru, Ir-based and graphene-supported nano-structured catalyst through an easily scalable, cost-effective, surfactant-free approach has been proposed. XRD, SEM, TEM images and EDX maps showed the formation of trimetallic NiRuIr alloy nanoparticles (average diameter: 8 nm) supported on a few-layer graphene. After characterization, the HER stability and activity of the sample were tested in a 0.5 M H2SO4, in a KCl neutral solution as well as in real seawater. In the acidic electrolyte environment a 0.06 V overpotential was maintained even after 11,000 cycles and the Tafel slope recorded was very low (28 mV/dec). In the neutral solution a very low overpotential (0.10 V) and a low Tafel slope (72 mV/dec) were also obtained. Furthermore, in real seawater the sample exhibits a Tafel slope of 48 mV/dec, maintains a low overpotential of 0.08 V for 250 cycles and a constant current density for 200 h of test without significant losses and with almost a 100% hydrogen production efficiency. The results obtained proved the remarkable HER performance of the synthesized electrocatalyst, especially in real seawater in virtue of synergistic alloying effects and the presence of the graphene support. Keywords: Trimetallic alloy, NiRuIr alloy, Seawater, Hydrogen evolution reaction, High stability, High H2 productio

Numerical computation of a confined sediment-water mixture in uniform flow

The purpose of this paper is to simulate a laminar mud flow confined in a narrow rectangular open channel. The flow bed is an erodible layer made up of the same material involved in the flow; the equilibrium condition between the moving and non moving layer is assumed. The mud mixture under consideration is ruled by Herschel-Bulkley’s shear thickening rheological law. It is supposed that the local volumetric concentration is linearly increasing with the depth and it is constantly equal to its maximum value where the local velocity is smaller than a threshold value. Relations among rheological parameters and concentration are obtained through laboratory rheometric tests. Turbulence effects and Coulombian stresses are ignored. To get the flow velocity, the momentum equation has to be integrated along the flow cross section. Unfortunately, it is very difficult to integrate this equation using H-B rheological law, since there are different stress functions and it is not possible to know a priori the sub-domains of them (plug, non plug and bed regions). In the present work a modified rheological law, continuous over the whole domain of integration is employed and the momentum equation is integrated numerically. This modified law is obtained by adding a constant correcting the denominator in the H-B stress functions: strictly speaking, there are not dead zones or plug any more. However it is noteworthy that, using a small constant, the model produces a good simulation of plug and dead zone: that is velocity gradient is very small there. The mathematical model has two parameters: maximum concentration and threshold velocity. These parameters are adjusted by back-analysis with measurements from laboratory flume experiments in uniform flow conditions

Agopuntura comunitaria. Una strategia abitativa per Vila Nova Esperança

I numerosi programmi di slum upgrading in atto nello Stato di São Paulo perseguono l’integrazione socio-spaziale attraverso la rigenerazione delle realtà informali, per far sì che gli abitanti possano avere accesso a beni e servizi primari e raggiungere così, in maniera reale, standard di vita cittadini. Tali interventi sono diversificati: risentono del luogo, della storia della comunità, della sua permanenza nell’area, della presenza o assenza di zone di rischio. Tra le tante strategie percorribili, il nostro contributo intende presentare un’ipotesi di intervento per insediamenti informali. Si tratta di un progetto sperimentale per abitazioni unifamiliari verificato in Vila Nova Esperança, piccola favela ricadente in parte nel Comune di São Paulo e in parte in quello di Taboão da Serra, e per la quale attualmente non sono previsti interventi di rigenerazione. Lo studio, condotto attraverso sopralluoghi e interviste ai favelados, ha consentito una mappatura dell’area, alla luce degli obiettivi della ricerca. Il fine è stato quello di definire un progetto di abitazioni di base minima, la cui realizzazione potesse avvenire in tempo breve, prevedendo al contempo anche un’espansione programmata tanto dell’impianto quanto del sistema-casa. La caratteristica principale della strategia proposta è infatti la volontà di fornire una possibile metodologia di intervento a lungo termine, potenzialmente capace di incidere gradualmente sull’assetto della comunità. L’elaborazione si basa sulla volontà di conservare la ricchezza sociale riscontrata nella comunità, incidendo sulle condizioni di vita e di convivenza attraverso il progetto dell’abitare quale motore per attivare il miglioramento e contribuire allo sviluppo dell’area. Così, partendo da considerazioni urbano-architettoniche ampie ed articolate, si è ragionato sulle modalità di recupero e riconfigurazione degli spazi aperti. Mentre il progetto di architettura, calato nel tessuto consolidato del caso di studio, ha parallelamente previsto la definizione di luoghi a carattere collettivo destinati ad accrescere la coesione comunitaria già riscontrata nella favela

Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects

A review on potentials and challenges of nanolubricants as promising lubricants for electric vehicles

AbstractThe most remarkable difference between electric vehicles (EVs) and conventional ones is the fuel burning dependency of the internal combustion engine, while the emerging EVs operate on electric motors. These alternations create staggering shifts in both lubricants' market demand and performance specifications. Lubricants for electrical powertrain constitutes greases, transmission oils, and lubricants for auxiliary systems and do not rely on engine oils as internal combustion vehicles. The new standards will be more focused on lubricants' electrical properties such as breakage voltage and conductivity, coupled with tribological performance under high rpm, corrosion resistance and thermal management benchmarks. This paper thematically reviews the different studies performed with nanolubricants, and how they match EVs' operational requirements. Conclusions from this study can be considered as guidelines for the potential application of nanolubricants in EVs and possible future research that can be accomplished on the topic

Prenatal screening and counseling for genetic disorders

Introduction: The carriers of the same autosomal recessive disorder are usually unaware of onset of the genetic diseases in the children even if screenings are available for many of these disorders. In this paper, we report the experience of the Prenatal Diagnosis Center of AOU Federico II and we discuss the role of the screening for beta-thalassemia (BT), cystic fibrosis (CF) and for other rare genetic disorders. Materials and Methods: We analyzed retrospectively the indication for Prenatal Diagnosis (PD) of all the couples referred to our center from January 1993 to May 2013. We divided our sample into three groups: couples at high risk for BT, for CF and for other rare genetic disorders. Results: From January 1993 to May 2013, we performed 1269 PD for genetic disorders. There are still couples who discovered to be carriers of BT by screening after the birth of the affected child (n=51 (11,3%)); the majority of the people were screened for CF carrier after the birth of an affected child (n=155 (80,7%)) or through the cascade screening (n=28 (14,6%)). Large-scale screenings for rare genetic conditions are not available and people were screened only if they have a positive familial history. Conclusion: Parental screening is available for many severe and rare diseases whose genetic origin is known. The proportion of patients referred for very high-risk indications increased over time with an higher demand for rare disease. An adequate counseling is fundamental to identify women at risk for having affected child. Screening, counseling and PD of genetic diseases is a complex matter and needs for a continuous update

Mechanical characterization of individual polycrystalline carbon tubes for use in electrical nano-interconnects

Polycrystalline carbon tubes were generated by CVD inside electrochemically prepared nano-porous anodic aluminium oxide membranes. This method produced nano-tubes without catalyst, featuring polycrystalline and a few layer thick walls. Individual tubes could be isolated and suspended on microfabricated substrates such that they formed single-side clamped beams. These beams were then used to investigate their mechanical properties employing electrostatic forces for bending the tubes beyond their mechanical stability where pull-in occurs, which could be detected by monitoring the current flowing from the tube to the substrate

Water-Mediated Nanostructures for Enhanced MRI: Impact of Water Dynamics on Relaxometric Properties of Gd-DTPA

Recently, rational design of a new class of contrast agents (CAs), based on biopolymers (hydrogels), have received considerable attention in Magnetic Resonance Imaging (MRI) diagnostic field. Several strategies have been adopted to improve relaxivity without chemical modification of the commercial CAs, however, understanding the MRI enhancement mechanism remains a challenge. Methods: A multidisciplinary approach is used to highlight the basic principles ruling biopolymer-CA interactions in the perspective of their influence on the relaxometric properties of the CA. Changes in polymer conformation and thermodynamic interactions of CAs and polymers in aqueous solutions are detected by isothermal titration calorimetric (ITC) measurements and later, these interactions are investigated at the molecular level using NMR to better understand the involved phenomena. Water molecular dynamics of these systems is also studied using Differential Scanning Calorimetry (DSC). To observe relaxometric properties variations, we have monitored the MRI enhancement of the examined structures over all the experiments. The study of polymer-CA solutions reveals that thermodynamic interactions between biopolymers and CAs could be used to improve MRI Gd-based CA efficiency. High-Pressure Homogenization is used to obtain nanoparticles. Results: The effect of the hydration of the hydrogel structure on the relaxometric properties, called Hydrodenticity and its application to the nanomedicine field, is exploited. The explanation of this concept takes place through several key aspects underlying biopolymer-CA's interactions mediated by the water. In addition, Hydrodenticity is applied to develop Gadolinium-based polymer nanovectors with size around 200 nm with improved MRI relaxation time (10-times). Conclusions: The experimental results indicate that the entrapment of metal chelates in hydrogel nanostructures offers a versatile platform for developing different high performing CAs for disease diagnosis