Rayleigh-like instability in the ion-shaping of Au-Ag alloy nanoparticles embedded within a silica matrix

We have studied how spherical 23 ± 3 nm Au(45)Ag(55) nanoparticles embedded within a silica matrix transform into prolate nanorods and nanowires by irradiating them with swift heavy ions. Samples were irradiated at room temperature and normal incidence with 74 MeV Kr and 36 MeV S ions for fluences up to 1.0 × 10(15) cm(-2). We demonstrate the existence of two regimes: (i) below a critical fluence, ～ 2.0 × 10(14) cm(-2), the transformation of the spherical nanoparticle into a nanorod is an individual process, i.e. each nanoparticle transforms into a single nanorod; (ii) for larger fluences the transformation from nanorod to nanowire becomes a collective process, i.e. the break up and dissolution of unstable nanorods contribute to the growth of long nanowires. The passage from the first to the second regime can be interpreted in terms of a Rayleigh-like instability under irradiation. The latter becomes active when the diameter of the nanowire approaches its saturation width under irradiation. Furthermore, we show that the composition of the alloy is only slightly modified during the ion-shaping process. Finally, the energy and the fluence thresholds for deformation and the deformation strain-rate are estimated.     

Communication via Mobile Vesicles in Brane Calculi

P systems and Brane calculi are two (families of) computational models inspired by the structure and the functioning of living cells. Although they have different goals there is a recent growing of interests in results that bridge the two research areas.Here we consider an important kind of communication based on the natural budding of mobile membranes (e.g., Golgi apparatus) that is already defined for P systems and we show how to construct an analogous communication in the basic Phago/Exo/Pino Brane calculus.     

Viscosimetric studies on 2-methoxyethanol + 1,2-dimethoxyethane binary mixtures from −10 to 80°c

The kinematic viscosities (v) were measured for nine binary solvent mixtures of 2-methoxyethanol (ME) + 1,2-dimethoxyethane (DME) at nineteen temperatures ranging from ?10 to +80°C. The experimental data have been used to test some empirical equations of the type v = v(T), v = v(X₁) and v = v(T, X₁). The viscosities of all the mixtures increase from the values of pure DME to that of ME as the mole fraction of ME increases, and always yield a negative excess property (v^E) at all the investigated temperatures. Furthermore, thermodynamic parameters of viscous flow have been evaluated on the basis of the Eyring theory. The excess free energy of activation of viscous flow (ΔG^E) vs X₂ plot suggests the presence of a stable hetero-adduct, having ME : DME = 1 : 1 stoichiometric ratio.     

Fingerprint Clustering with Bounded Number of Missing Values

The problem of clustering fingerprint vectors with missing values is an interesting problem in Computational Biology that has been proposed in Figueroa et al. (J. Comput. Biol. 11(5):887–901, 2004). In this paper we show some improvements in closing the gaps between the known lower bounds and upper bounds on the approximability of variants of the biological problem. Moreover, we have studied two additional variants of the original problem proposed in Figueroa et al. (Proc. 11th Computing: The Australasian Theory Symposium (CATS), CRPIT, vol. 41, pp. 57–60, 2005). We prove that all such problems are APX-hard even when each fingerprint contains only two unknown positions and we present a greedy algorithm that has constant approximation factors for these variants. Despite the hardness of these restricted versions of the problem, we show that the general clustering problem on an unbounded number of missing values such that they occur for every fixed position of an input vector in at most one fingerprint is polynomial time solvable.     

Reliability of RF MEMS switches due to charging effects and their circuital modelling

The reliability of RF MEMS switches is typically reduced by charging effects occurring in the dielectrics. The aim of this paper is to discuss these effects, and to propose analytical and equivalent circuit models which account for most of the physical contributions present in the structure.     

Development of virtual data acquisition systems based on multimedia internetworking

This paper proposes a novel approach centered on multimedia internetworking for the development of Distributed Virtual Instruments (DVI). Multimedia internetworking refers to network infrastructures, protocols, models, applications and techniques being currently deployed over the Internet to support multimedia applications, e.g., videoconferencing, video-on-demand, shared workspaces. It is applied to broaden the concept of virtual instrument and enable new measurement patterns leveraging efficiency and interactivity. A DVI is a virtual instrument split into possibly multiple and independent parts, sender and receiver, which are linked by real-time continuous media and control streams. Senders and receivers are built by using open, composable and modular components based on a time sensitive actor framework and glued by multimedia middleware. A prototype is described to demonstrate the potential and the benefits of the proposed approach.     

Optimisation of a thick-film 10–400 N force sensor

The ring-on-ring bending principle allows the fabrication of simple, low-cost thick-film piezoresistive sensors for compressive forces in the 10–400 N range. However, some imperfections are encountered in its basic embodiment, such as relatively high force-signal hysteresis and nonrepeatability (up to ca. 5%). These shortcomings were studied in this work, and major improvements have been achieved. Hysteresis was found to be mainly due to friction at the outer support ring, and was considerably reduced by inserting a compliant silicone glue ring. The same glue ring was used to permanently bond the sensor to a rigid base, thereby giving well-defined and constant boundary conditions and also considerably improving the repeatability of the sensitivity. Overall, hysteresis and repeatability error were reduced down to a level of ca. 1%.     

Chemical and biological variability of hot pepper fruits (Capsicum annuum var. acuminatum L.) in relation to maturity stage

The aim of the present work was to evaluate the chemical composition and the radical-scavenging and antioxidant activities of hot pepper fruits (Capsicum annuum L. var. acuminatum) at three maturity stages (small green, green and red). GC–MS analysis of n-hexane and chloroform fractions showed a different composition between the three stages of ripening. The first stage of maturation (small green) showed the highest radical-scavenging activity (IC₅₀ of 129 μg/ml). Using the bovine brain peroxidation assay, the methanolic extract of green pepper showed significant antioxidant activity (IC₅₀ of 522 μg/ml). Addition of methanolic extract of red and green pepper inhibited oxidation of linoleic acid. Methanolic extract of red pepper showed greater antioxidative potency than the others (IC₅₀ of 3 μg/ml). The different composition of lipophilic compounds and the various amount of phenolics, showed in the three stage of ripening of C. annuum var. acuminatum fruits, modifies the antioxidant activity.     

Isolation of a hydroxytyrosol-rich extract from olive leaves (<Emphasis Type="Italic">Olea Europaea</Emphasis> L.) and evaluation of its antioxidant properties and bioactivity

In this research, a phenol extract of high hydroxytyrosol (OLPE) content was obtained from olive leaves (Olea europaea L.), and subsequently tested under different contexts. The method used to obtain the OLPE basically involved two steps: the use of strongly-acid aqueous steam, generated from 10% HCl (v/v) at 100°C, to directly hydrolyse the native complex phenols from integral olive leaves, and OLPE recovery by liquid–liquid extraction with ethyl acetate. Hydrolysis time was 1 h. Finally, the dried extract was dissolved in distilled water. The OLPE total phenols were determined by Folin–Ciocalteu’s method and by HPLC analysis. Hydroxytyrosol was about 92% of the total phenols present in OLPE, and the yield was about 0.2% on fresh leaves. OLPE showed antioxidant effects on different food lipids and did not inhibit lactic acid bacteria growth; however, it showed cytotoxicity on NIH/3T3 fibroblasts and human umbilical vein endothelial cells at concentrations higher than 0.32 mM (as hydroxytyrosol).