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.     

Optimization of pump absorption in MOF lasers via multi-long-period gratings: design strategies

Different strategies for designing optical couplers, optimized to enhance the pump absorption in the rare-earth-doped core of microstructured fiber lasers, are illustrated. Three kinds/configurations of optical couplers have been designed and compared as examples of the different design strategies which can be followed. Their effectiveness to enhance the performance of an ytterbium-doped, double cladding, microstructured optical fiber laser has been accurately simulated. They consist of a suitable cascade of multiple long-period gratings (MLPGs) inscribed in the fiber core region. The characteristics of the MLPG couplers have been simulated via a homemade computer code based on both rate equations and an extended coupled mode theory. The proposed MLPG couplers seem particularly useful in the case of low rare-earth concentration but, even for a middle-high ytterbium concentration, as N(Yb)=5×10(25) ions/m(3), the slope efficiency S can be increased up to 20%, depending on the fiber length.     

Numerical integration of a pressure‐dependent,non‐linear kinematic hardening constitutive model for large strain cyclic plasticity of metals

A Gurson‐based constitutive model is presented, which includes non‐linear mixed isotropic–kinematic hardening and creep, and allows the analysis of problems involving arbitrarily large plastic strains. This model was developed with the main objective of allowing, on the basis of a single set of material parameters, the numerical simulation of all the main features of cold metal forming processes, which usually imply severe loading–unloading cycles with very large plastic strains, difficult to be correctly reproduced numerically. A suitable integration scheme of the rate equations is described and implemented into a finite element code. The results obtained are compared with some reference experimental ones; an application of the model for the simulation of wire drawing processes is also presented. Copyright © 2011 John Wiley & Sons, Ltd.     

A low-delay MAC solution for MIMO ad hoc networks

Beamforming is regarded as a key element for multiantenna ad hoc networks. However, it cannot simultaneously provide the omnidirectional and long-range coverage required by broadcast transmissions [1]–[4], a problem known as the Asymmetry in Gain. We propose a scheme for control packet exchange over an extended radio coverage based on a Space Time Code technique. This solution is shown to solve the Asymmetry in Gain issue, and is proposed as part of a MAC protocol for MIMO ad hoc networks, whose performance benefits include increased throughput and reduced delay and energy consumption.     

Energy conservation in wireless sensor networks: A survey

In the last years, wireless sensor networks (WSNs) have gained increasing attention from both the research community and actual users. As sensor nodes are generally battery-powered devices, the critical aspects to face concern how to reduce the energy consumption of nodes, so that the network lifetime can be extended to reasonable times. In this paper we first break down the energy consumption for the components of a typical sensor node, and discuss the main directions to energy conservation in WSNs. Then, we present a systematic and comprehensive taxonomy of the energy conservation schemes, which are subsequently discussed in depth. Special attention has been devoted to promising solutions which have not yet obtained a wide attention in the literature, such as techniques for energy efficient data acquisition. Finally we conclude the paper with insights for research directions about energy conservation in WSNs.