Magnetic core nanoparticles coated by titania and alumina for water and wastewater remediation from metal contaminants

Nanomaterials have been widely used for remediation of contaminated streams. However, using nanomaterials within water and wastewater might be dangerous since fate and health impact of nanoparticles is still unknown. Therefore, it is mandatory to avoid contamination by removing all the nanoparticles from the treated stream. This can be performed by immobilizing the nanoparticles on supports, although this approach leads to lower efficiency values. Another possibility is to use suspended nanoparticles: in this case, efficiency of the treatment process is enhanced. If nanomaterials have a magnetic core-shell, then suspended nanoparticles can be removed in a safe and easy was by using magnetic traps. In the present study, new nanomaterials based on magnetic core-shell structure were developed: the magnetic core guarantees a complete removal from the treated water and wastewater streams, whereas the shell (coating) is functionalized to eliminate specific classes of pollutants. A first experimental step allowed to produce the magnetic nanoparticles and perform a coating with SiO2 in order to electrically isolate the core from the ambient and to avoid degradation. This procedure is well established and the production of SiO2 coated magnetic nanoparticles are nowadays a validated procedure by using a spinning disk reactor.In a successive step, the silica shell magnetic cores were coated by titania and/or activated alumina particles with the aim of removing metals by adsorption. In the present study, the arsenic adsorption capacity of silica shell magnetic cores nanoparticles coated by titania and/or activated was investigated through kinetic experiments. All the tested adsorbents performed very well showing very rapid rates of the adsorption process. Among them, the best performing media were found to be those with titania coating. The best fitting kinetic model was found to be the pseudo-second order one for all of the adsorbents

The mass accretion rate of galaxy clusters: a measurable quantity

We explore the possibility of measuring the mass accretion rate (MAR) of galaxy clusters from their mass profiles beyond the virial radius $R_{200}$. We derive the accretion rate from the mass of a spherical shell whose inner radius is $2R_{200}$, whose thickness changes with redshift, and whose infall velocity is assumed to be equal to the mean infall velocity of the spherical shells of dark matter halos extracted from $N$-body simulations. This approximation is rather crude in hierarchical clustering scenarios where both smooth accretion and aggregation of smaller dark matter halos contribute to the mass accretion of clusters.Nevertheless, in the redshift range $z=[0,2]$, our prescription returns an average MAR within $20-40 \%$ of the average rate derived from the merger trees of dark matter halos extracted from $N$-body simulations. The MAR of galaxy clusters has been the topic of numerous detailed numerical and theoretical investigations, but so far it has remained inaccessible to measurements in the real universe. Since the measurement of the mass profile of clusters beyond their virial radius can be performed with the caustic technique applied to dense redshift surveys of the cluster outer regions, our result suggests that measuring the mean MAR of a sample of galaxy clusters is actually feasible. We thus provide a new potential observational test of the cosmological and structure formation models.Comment: 11 pages, 7 figures, 5 tables, minor text modifications to match the published version, typos correcte

Multi-function ESD protection circuit for UHF RFID devices in CMOS technology

The design and implementation of an electrostatic discharge protection suitable for UHF RFID devices in CMOS technology is presented. The circuit implements three fundamental functions for the RF interface: power limiting, backscatter modulation and electrostatic discharge protection. Since all functions are achieved by the same MOS device the additional shunt capacitance at the RF inputs is limited. Therefore the maximum reading distance of the RFID device is improved without sacrificing the electrostatic protection level

Power Management Circuits for Low-Power RF Energy Harvesters

The paper describes the design and implementation of power management circuits for RF energy harvesters suitable for integration in wireless sensor nodes. In particular, we report the power management circuits used to provide the voltage supply of an integrated temperature sensor with analog-to-digital converter. A DC-DC boost converter is used to transfer efficiently the energy harvested from a generic radio-frequency rectifier into a charge reservoir, whereas a linear regulator scales the voltage supply to a suitable value for a sensing and conversion circuit. Implemented in a 65 nm CMOS technology, the power management system achieves a measured overall efficiency of 20%, with an available power of 4.5 μW at the DC-DC converter input. The system can sustain a temperature measurement rate of one sample/s with an RF input power of −28 dBm, making it compatible with the power levels available in generic outdoor environments

Synthetic character fidelity through non-verbal behaviour in computer games

Artificial Intelligence in games has historically focused on providing a challenging opponent for a player and narrative development. Scope exists to increase the fidelity of synthetic characters throughout the game to create a more immersive game play experience. This requires both visual and behavioural fidelity, and while graphics are nearing photorealism, synthetic characters' behaviour is still unrealistic. Non-verbal behaviour of synthetic characters has to date received little attention and so the scope and participants of non-verbal behaviour requires identification. We review the range of spatial and task scenarios relevant in a game context, then identify categories of non-verbal behaviour and go on tot summarise their role in communication and propose their incorporation in the design of non-player characters. Finally we review how non-verbal behaviour of synthetic agents might increase immersion for a player and identify interaction techniques that might facilitate non-verbal communication with players and non-players characters alike

Terrestrial Laser Scanner for Surveying and Monitoring Middle Age Towers

We had the opportunity to make surveying of some middle age towers located in Emilia Romagna region (Italy): Ghirlandina tower (Modena), \u201cDella Sagra\u201d tower (Carpi, Modena) , Asinelli tower (Bologna). Those towers are very interesting by architectural and artistic point of view; Ghirlandina and Asinelli are Cultural Heritage site of UNESCO.Terrestrial laser scanner (TLS) instrument has been used with an accuracy at 1 cm level in order to obtain good restitution in absolute coordinates, even with a precise topographic determination of GCP (Ground Control Points). Tridimensional restitution of the towers is here presented; we would like to point out the attention on the way that we use the TLS for enhancing the geometrical characteristics, particularly the height of the towers and the axis development that were determined through the trajectory of barycenter of transversal sections.The determination of actual geometry is essential for the study of the buildings and it is a first fundamental step for monitoring the towers

A Low-Power Sigma-Delta Modulator for Healthcare and Medical Diagnostic Applications

This paper presents a switched-capacitor Sigma-Delta modulator designed in 90-nm CMOS technology, operating at 1.2-V supply voltage. The modulator targets healthcare and medical diagnostic applications where the readout of small-bandwidth signals is required. The design of the proposed A/D converter was optimized to achieve the minimum power consumption and area. A remarkable performance improvement is obtained through the integration of a low-noise amplifier with modified Miller compensation and rail-to-rail output stage. The manuscript also presents a set of design equations, from the small-signal analysis of the amplifier, for an easy design of the modulator in different technology nodes. The Sigma-Delta converter achieves a measured 96-dB dynamic range, over a 250-Hz signal bandwidth, with an oversampling ratio of 500. The power consumption is 30 μW, with a silicon area of 0.39 mm²