Analysis of nitride storage non-volatile memories with HfSiOx blocking dielectric and TiN metal gate for low power embedded applications

Nitride storage non-volatile memories with hafnium silicate (HfSiO_x) blocking dielectric and titanium nitride (TiN) metal gate aimed at low power embedded applications beyond the 45 nm node, have been fabricated and investigated. In addition to presenting the typical figures of merit of flash memories, the scalability of the devices has been assessed. We have also investigated the physical origin of the observed memory features.     

Experimental Electron Mobility in ZnO: A Reassessment Through Monte Carlo Simulation

The low-field electron mobility in bulk ZnO has been the object of extensive experimental studies, mainly through measurement of the temperature-dependent Hall effect. In this work, we reassess the experimental results through direct simulations of Hall measurements, performed with a Monte Carlo transport model and taking into account all the major scattering mechanisms. The deformation potentials required to compute acoustic and optical phonon scattering are derived from first-principles computations, and an original theory for charged-dislocation-line scattering is proposed and implemented. Monte Carlo results for the electron mobility and the Hall factor are compared with analytical expressions derived with the relaxation-time approximation, which is found to be adequate at low temperatures where inelastic scattering effects due to optical phonons are negligible.     

Post-Impact Mechanical Characterisation of Glass and Basalt Woven Fabric Laminates

Two woven fabric laminates, one based on basalt fibres, the other on E-glass fibres, as a reinforcement for vinylester matrix, were compared in terms of their post-impact performance. With this aim, first the non-impacted specimens were subjected to interlaminar shear stress and flexural tests, then flexural tests were repeated on laminates impacted using a falling weight tower at three impact energies (7.5, 15 and 22.5J). Tests were monitored using acoustic emission analysis of signal distribution with load and with distance from the impact point. The results show that the materials have a similar damage tolerance to impact and also their post-impact residual properties after impact do not differ much, with a slight superiority for basalt fibre reinforced laminates. The principal difference is represented by the presence of a more extended delamination area on E-glass fibre reinforced laminates than on basalt fibre reinforced ones.     

Microfluidic devices modulate tumor cell line susceptibility to NK cell recognition

This study aims to adoptively reduce the major histocompatibility complex class I (MHC-I) molecule surface expression of cancer cells by exposure to microfluid shear stress and a monoclonal antibody. A microfluidic system is developed and tumor cells are injected at different flow rates. The bottom surface of the microfluidic system is biofunctionalized with antibodies (W6/32) specific for the MHC-I molecules with a simple method based on microfluidic protocols. The antibodies promote binding between the bottom surface and the MHC-I molecules on the tumor cell membrane. The cells are injected at an optimized flow rate, then roll on the bottom surface and are subjected to shear stress. The stress is localized and enhanced on the part of the membrane where MHC-I proteins are expressed, since they stick to the antibodies of the system. The localized stress allows a stripping effect and consequent reduction of the MHC-I expression. It is shown that it is possible to specifically treat and recover eukaryotic cells without damaging the biological samples. MHC-I molecule expression on treated and control cell surfaces is measured on tumor and healthy cells. After the cell rolling treatment a clear reduction of MHC-I levels on the tumor cell membrane is observed, whereas no changes are observed on healthy cells (monocytes). The MHC-I reduction is investigated and the possibility that the developed system could induce a loss of these molecules from the tumor cell surface is addressed. The percentage of living tumor cells (viability) that remain after the treatment is measured. The changes induced by the microfluidic system are analyzed by fluorescence-activated cell sorting and confocal microscopy. Cytotoxicity tests show a relevant increased susceptibility of natural killer (NK) cells on microchip-treated tumor cells.     

Results of Measuring the Influence of Casimir Energy on Superconducting Phase Transitions

The ALADIN experiment aims at observing how the critical magnetic field of a superconducting aluminum film is modified, when it constitutes one of the reflecting surfaces of a Casimir cavity. If successful, such an observation would reveal the influence of vacuum energy on the superconducting phase transition. In this paper, a rigorous analysis of experimental data is reported, the results are discussed and compared with theoretical predictions based on Lifshitz theory of dispersion forces, and the BCS formula for the optical conductivity of superconductors. Thanks to this rigorous analysis, it can now be asserted that in the region of energy where it is expected that Casimir energy is comparable with condensation energy and the deviations of critical field from BCS formula to be not negligible, an anomalous behavior is found.     

Tribological Characterization of WC–Co Plasma Sprayed Coatings

Atmospheric plasma spraying of WC coatings is typically characterized by increased decarburization, with a consequent reduction of their wear resistance. Indeed, high temperature and oxidizing atmosphere promote the appearance of brittle crystalline and amorphous phases. However, by using a high helium flow rate in a process gas mixture, plasma spraying may easily be optimized by increasing the velocity of sprayed particles and by reducing the degree of WC dissolution. To this purpose, a comparative study was performed at different spray conditions. Both WC–Co powder and coating phases were characterized by X-ray difraction. Their microstructure was investigated by scanning electron microscopy. Mechanical, dry sliding friction, and wear tests were also performed. The wear resistance was highly related to both microstructural and mechanical properties. The experimental data confirmed that high-quality cermet coatings could be manufactured by using optimized Ar–He mixtures. Their enhanced hardness, toughness, and wear resistance resulted in coatings comparable to those sprayed by high velocity oxygen-fuel.     

Morphology Modification of Polyethylene/Clay Nanocomposite Samples under Convergent Flow

The morphology of PE/CL nanocomposite samples subjected to convergent flows is studied. Elongational flow – the typical flow involved in spinning and film‐blowing processing operations – significantly increases with the reduction of the capillary diameter. The values of the convergent extensional stress (calculated by Cogswell's formula) for the PE/CL systems, for all the adopted capillary geometries, are greater than the calculated values for pure polyethylene. The applied convergent flow, at the entrance of the capillary, is able to change the clay morphology and consequently the final material properties on the PE/CL system with limited affinity between the matrix and organo‐modified clay particles.

     

Synthesis and Characterization of BaTiO3-Based Foams with a Controlled Microstructure

BaTiO₃ foams were synthesized via the direct foaming method using commercial powders. In order to control the microstructure and by extension the properties, synthesis parameters such as foaming agent, composition, sintering time, and sintering temperature were varied to determine their influence. The effect of each parameter on the microstructure was measured and characterized using scanning electron microscopy, image analysis, helium pycnometry, and mercury porosimetry. Microstructure was classified in terms of strut characteristics, average grain size, average cell window size, porosity, and grain boundary integrity. For example, foams with 30% ceramic volume were synthesized using a laboratory-developed and a commercial polyurethane (PU) system, both silicon (Si) free. When sintered at 1400°C for 8 h, they produced thick, dense struts and uniform pore-size distributions, although with different characteristics. The foam prepared with the laboratory-synthesized PU had a porosity of 90%, an average grain size of 44.4 μm, and an average cell window size of 66.7 μm, while the foam prepared with the commercial PU had a porosity of 87%, an average grain size of 20 μm, and an average cell window size of 99 μm.