Matrix Addressing of an Electronic Surface Switch Based on a Conjugated Polyelectrolyte for Cell Sorting

Spatial control of cell detachment is potentially of great interest when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes. Here, selective detachment and cell sorting of human primary keratinocytes and fibroblasts is achieved using thin films of a conjugated polymer. Upon electrochemical oxidation, the polymer film swells, cracks, and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography to fabricate a cross‐point matrix with polymer pixels that can be individually addressed and thus detached. Detachment occurs above a well‐defined threshold of +0.7 V versus Ag/AgCl, allowing the use of a relatively simple and easily manufactured passive matrix‐addressing configuration, based on a resistor network, to control the cell‐sorting device.     

Functional nanocomposites with graphene-DNA hybrid fillers: Synthesis and surface properties under UV irradiation

In this work, nanocomposites containing assemblies of graphene nanoplatelets (GNP) and double-stranded DNA are investigated as UV-sensitive materials, as they show good electrical properties combined with the chemical sensitivity of DNA to UV radiation, particularly to the more energetic UV-C band. Nanocomposite films were prepared by drop-casting technique after embedding the graphene-DNA fillers in a flexible polydimethylsiloxane (PDMS) matrix using a suitable solvent. The synthesis was optimized in order to improve the dispersion of the graphene-DNA elements in the polymer matrix, as the sensing properties of the nanocomposite materials are highly affected by the amount and homogeneity of the filler dispersion. The electrical and thermal properties of the GNP-DNA/PDMS films, as well as their surface morphology and wettability, were investigated before and after exposure to UV-C radiation using complementary techniques. Results give information on the potential applications of these novel functional nanocomposites for radiation monitoring in environments that are characterized by high levels of biologically-damaging UV radiation.     

Engineering Energy Efficient Visual Sensor Network Applications Using Skeletons

Visual sensor networks (VSNs) perform complex scene analysis algorithms that require significant computations and communications. Under this respect, the use of skeletons contributes to reduce the complexity of VSN programming and may ensure an easier and better optimization of the code. In this context, we propose INS, a stencil based skeleton targeted for wireless/visual sensor networks (W/VSNs) and give a preliminary analysis of its benefits using tracking as a case study. INS abstracts a distributed approximation schema in which the estimation of a given metric is organized in a sequence of steps. Each step includes collecting estimates from some neighbor nodes and local computation of a new approximation. In particular, INS takes inspiration from some stencil based skeletons proposed for parallel computation and merges it with the classical event driven model typical of sensor programming. As a result, the execution of each step is triggered by the detection of a relevant event in the environment. Tracking consists in periodically predicting position and velocity of one or more mobile targets. We discuss how INS can be instantiated to a distributed version of Kalman filtering. As energy efficiency is central in W/VSNs, we derive analytic models for energy dissipation of the INS skeleton depending on different concepts of neighborhood for the data exchanged at each step. Then, these models are used to guide the deployment of our tracking application on a real scenario.     

Free radicals and antioxidants in food and in vivo: What they do and how they work

A wide variety of oxygen free radicals and other reactive oxygen species can be formed in the human body and in food systems. Transition metal ions accelerate free‐radical damage. Antioxidant defenses, both enzymic and nonenzymic, protect the body against oxidative damage, but they are not 100% efficient, and so free‐radical damage must be constantly repaired. Nonenzymatic antioxidants are frequently added to foods to prevent lipid peroxidation. Several lipid antioxidants can exert prooxidant effects toward other molecules under certain circumstances, and so antioxidants for food and therapeutic use must be characterized carefully. Methods of measuring oxidative damage and trapping free radicals in vivo are briefly discussed. Such methods are essential in checking proposals that increased intake of food‐derived antioxidants (such as antioxidant vitamins) would be beneficial to humans.