Roberto Guerrieri

Numerical simulation of polycrystalline-Silicon MOSFET's

In this paper we investigate polycrystalline-silicon MOSFET operation by means of a two-dimensional device-analysis program developed at the University of Bologna. The grain-boundary model used in this study allows for both donor and acceptor states at the interface, and assumes a drift-diffusion transport mechanism, consistently with the general structure of the code. Results achieved thus far allow us to interpret the increased threshold voltage experimentally observed in polycrystalline-silicon MOSFETs and the device transconductance in strong inversion; on the other hand, the current increase occurring at negative gate voltages is not justified by the numerical model so far implemented. It is believed that field-enhanced emission rates and impact ionization are possible mechanims to interpret the above conduction increase.

α-Tocopheryl succinate promotes selective cell death induced by vitamin K3 in combination with ascorbate

Background:A strategy to reduce the secondary effects of anti-cancer agents is to potentiate the therapeutic effect by their combination. A combination of vitamin K3 (VK3) and ascorbic acid (AA) exhibited an anti-cancer synergistic effect, associated with extracellular production of H2O2 that promoted cell death.Methods:The redox-silent vitamin E analogue α-tocopheryl succinate (α-TOS) was used in combination with VK3 and AA to evaluate their effect on prostate cancer cells.Results:Prostate cancer cells were sensitive to α-TOS and VK3 treatment, but resistant to AA upto 3.2u2009mM. When combined, a synergistic effect was found for VK3–AA, whereas α-TOS–VK3 and α-TOS–AA combination showed an antagonist and additive effect, respectively. However, sub-lethal doses of AA–VK3 combination combined with a sub-toxic dose of α-TOS showed to induce efficient cell death that resembles autoschizis. Associated with this cell demise, lipid peroxidation, DNA damage, cytoskeleton alteration, lysosomal–mitochondrial perturbation, and release of cytochrome c without caspase activation were observed. Inhibition of lysosomal proteases did not attenuate cell death induced by the combined agents. Furthermore, cell deaths by apoptosis and autoschizis were detected.Conclusion:These finding support the emerging idea that synergistic combinations of some agents can overcome toxicity and other side-effects associated with high doses of single drugs creating the opportunity for therapeutically relevant selectivity.

Alpha-Tocopheryl Succinate Inhibits Autophagic Survival of Prostate Cancer Cells Induced by Vitamin K3 and Ascorbate to Trigger Cell Death

Background The redox-silent vitamin E analog α-tocopheryl succinate (α-TOS) was found to synergistically cooperate with vitamin K3 (VK3) plus ascorbic acid (AA) in the induction of cancer cell-selective apoptosis via a caspase-independent pathway. Here we investigated the molecular mechanism(s) underlying cell death induced in prostate cancer cells by α-TOS, VK3 and AA, and the potential use of targeted drug combination in the treatment of prostate cancer. Methodology/Principal Findings The generation of ROS, cellular response to oxidative stress, and autophagy were investigated in PC3 prostate cancer cells by using drugs at sub-toxic doses. We evaluated whether PARP1-mediated apoptosis-inducing factor (AIF) release plays a role in apoptosis induced by the combination of the agents. Next, the effect of the combination of α-TOS, VK3 and AA on tumor growth was examined in nude mice. VK3 plus AA induced early ROS formation associated with induction of autophagy in response to oxidative stress, which was reduced by α-TOS, preventing the formation of autophagosomes. α-TOS induced mitochondrial destabilization leading to the release of AIF. Translocation of AIF from mitochondria to the nucleus, a result of the combinatorial treatment, was mediated by PARP1 activation. The inhibition of AIF as well as of PARP1 efficiently attenuated apoptosis triggered by the drug combination. Using a mouse model of prostate cancer, the combination of α-TOS, VK3 and AA was more efficient in tumor suppression than when the drugs were given separately, without deleterious side effects. Conclusions/Significance α-TOS, a mitochondria-targeting apoptotic agent, switches at sub-apoptotic doses from autophagy-dependent survival of cancer cells to their demise by promoting the induction of apoptosis. Given the grim prognosis for cancer patients, this finding is of potential clinical relevance.

A Four-Shell Diffusion Phantom of the Head for Electrical Impedance Tomography

A four-shell head phantom has been built and characterized. Its structure is similar to that of nonhomogeneous concentric shell domains used by numerical solvers that better approximate current distribution than phantoms currently used to validate electrical impedance tomography systems. Each shell represents a head tissue, namely, skin, skull, cerebrospinal fluid, and brain. A novel technique, which employs a volume conductive impermeable film, has been implemented to prevent ion diffusion between different agar regions without affecting current distribution inside the phantom. Comparisons between simulations and phantom measurements performed over four days are given to prove both the adherence to the model in the frequency range between 10 kHz and 1 MHz and its long-term stability.

Active electrode IC combining EEG, electrical impedance tomography, continuous contact impedance measurement and power supply on a single wire

The IC presented integrates the front-end for EEG and Electrical Impedance Tomography acquisition on the electrode, together with contact impedance monitoring, so as to improve signal quality and functional integration of the two techniques for brain imaging applications. Only 4 wires connect the electrode to the back-end. The readout circuit consumes 1 mW, while the input referred noise for EEG signal acquisition is 0.45 μVRMS between 0.5 and 100 Hz, doubling when both EEG and EIT are acquired simultaneously.

Triangular Matrix Inversion on Heterogeneous Multicore Systems

Dense matrix inversion is a basic procedure in many linear algebra algorithms. Any factorization-based dense matrix inversion algorithm involves the inversion of one or two triangular matrices. In this work, we present an improved implementation of a parallel triangular matrix inversion for heterogeneous multicore CPU/dual-GPU systems.

The biocompatibility of materials used in printed circuit board technologies with respect to primary neuronal and K562 cells

Printed circuit board (PCB) technology can be used for producing lab-on-a-chip (LOAC) devices. PCBs are characterized by low production costs and large-scale development, both essential elements in the frame of disposable applications. LOAC platforms have been employed not only for diagnostic and/or analytical purposes, but also for identification and isolation of eukaryotic cells, including cancer and stem cells. Accordingly, the compatibility of the employed materials with the biological system under analysis is critical for the development of LOAC devices to be proposed for efficient and safe cell isolation. In this study, we analyzed the in-vitro compatibility of a large set of materials and surface treatments used for LOAC development and evaluation with quasi-standard PCB processes. Biocompatibility was analyzed on hippocampal primary cells (a model of attached cell cultures), in comparison with the reference K562 cell line (a model of cells growing in suspension). We demonstrate here that some of the materials under study alter survival, organization, morphology and adhesion capacity of hippocampal cells, and inhibit growth and differentiation of K562 cells. Nonetheless, a subset of the materials tested did not negatively affect these functions, thus demonstrating that PCB technology, with some limitations, is suitable for the realization of LOAC devices well compatible at least with these preparations.

Electronic Microsystems for Handling of Rare Cells

This review paper summarizes some of the most challenging issues regarding the development of electronic microsystems for the isolation, manipulation, and characterization of rare cells. Two relevant areas, namely, immunology for cancer therapy and monitoring of microbial contaminants in water, are presented as example applications which require handling of rare cells. Starting from these applications, the state of the art in electronic microsystem research is presented, and various solutions are discussed, highlighting the advantages and disadvantages of each technology and suggesting the need to integrate multiple solutions to meet the application requirements.

EIT Forward Problem Parallel Simulation Environment with Anisotropic Tissue and Realistic Electrode Models

Electrical impedance tomography (EIT) is an imaging technology based on impedance measurements. To retrieve meaningful insights from these measurements, EIT relies on detailed knowledge of the underlying electrical properties of the body. This is obtained from numerical models of current flows therein. The nonhomogeneous and anisotropic electric properties of human tissues make accurate modeling and simulation very challenging, leading to a tradeoff between physical accuracy and technical feasibility, which at present severely limits the capabilities of EIT. This work presents a complete algorithmic flow for an accurate EIT modeling environment featuring high anatomical fidelity with a spatial resolution equal to that provided by an MRI and a novel realistic complete electrode model implementation. At the same time, we demonstrate that current graphics processing unit (GPU)-based platforms provide enough computational power that a domain discretized with five million voxels can be numerically modeled in about 30 s.

Chip-to-chip communication based on capacitive coupling

This paper presents a review of the solutions proposed for chip-to-chip communication based on capacitive coupling. Circuit designs, assembly options and various different test cases are presented in this work. It is shown that this 3D technology is capable of transferring digital data between two dies at high-speed with low power consumption, and likewise analog signals without the need for any extra-wafer processing. The results presented highlight the key features of capacitive coupling when compared to other 3D interconnections and justify the effort to overcome some open issues and make it a marketable technology.