Adaptive smooth multicast protocol for multimedia transmission: Implementation details and performance evaluation

In this paper we propose a new single‐rate multicast congestion control scheme named Adaptive Smooth Multicast Protocol (ASMP), for multimedia transmission over best‐effort networks. The smoothness lays in the calculation and adaptation of the transmission rate, which is based on dynamic estimations of protocols' parameters and dynamic adjustment of the ‘smoothness factor’, as well. ASMP key attributes are: (a) TCP‐friendly behavior, (b) adaptive scalability to large sets of receivers, (c) high bandwidth utilization, and finally (d) smooth transmission rates, which are suitable for multimedia applications. We evaluate the performance of ASMP and investigate its behavior under various network conditions through extensive simulations conducted with the network simulator software (ns2). Simulation results show that ASMP can be regarded as a serious competitor of TFMCC and PGMCC. In many cases, ASMP outperforms TFMCC in terms of TCP‐friendliness and smooth transmission rates, while PGMCC presents lower scalability than ASMP. We have implemented ASMP on top of RTP/RTCP protocols in ns2 by adding all the RTP/RTCP protocol's attributes that are defined in RFC 3550 and related to quality of service metrics. Copyright © 2009 John Wiley & Sons, Ltd.     

Non‐Toxic Dry‐Coated Nanosilver for Plasmonic Biosensors

The plasmonic properties of noble metals facilitate their use for in vivo bio‐applications such as targeted drug delivery and cancer cell therapy. Nanosilver is best suited for such applications as it has the lowest plasmonic losses among all such materials in the UV‐visible spectrum. Its toxicity, however, can destroy surrounding healthy tissues and thus, hinders its safe use. Here, that toxicity against a model biological system (Escherichia coli) is “cured” or blocked by coating nanosilver hermetically with a about 2 nm thin SiO₂ layer in one‐step by a scalable flame aerosol method followed by swirl injection of a silica precursor vapor (hexamethyldisiloxane) without reducing the plasmonic performance of the enclosed or encapsulated silver nanoparticles (20–40 nm in diameter as determined by X‐ray diffraction and microscopy). This creates the opportunity to safely use powerful nanosilver for intracellular bio‐applications. The label‐free biosensing and surface bio‐functionalization of these ready‐to‐use, non‐toxic (benign) Ag nanoparticles is presented by measuring the adsorption of bovine serum albumin (BSA) in a model sensing experiment. Furthermore, the silica coating around nanosilver prevents its agglomeration or flocculation (as determined by thermal annealing, optical absorption spectroscopy and microscopy) and thus, enhances its biosensitivity, including bioimaging as determined by dark field illumination.     

Study of emulsions and foams stabilized with Phaseolus vulgaris or Phaseolus coccineus with the addition of xanthan gum or NaCl

The properties of oil/water emulsions stabilized with 1% w/v common bean (Phaseolus vulgaris L.) or scarlet runner bean (P. coccineus L.) proteins, extracted by isoelectric precipitation or ultrafiltration, at pH 7.0 and 5.5 were studied. The stability of emulsions, evaluated on the basis of droplet size, creaming, viscosity and protein adsorption measurements, is increased by the addition of xanthan (0.1 and 0.25% w/v). This is probably due to the increase in the continuous phase viscosity and the creation of a network, which prevents the oil droplets from coalescing. Also, the ability and stability of 1 or 2% w/v foams was studied. Xanthan (0.25% w/v) does not enhance foam formation, but promotes foam stability, possibly owing to the increased viscosity of the aqueous phase, making it more difficult for air to enter the system and create a satisfactory foam volume. The addition of NaCl destabilizes emulsions by lowering the energy barrier and therefore increasing the tendency of the oil droplets to aggregate. However, NaCl at a certain concentration seems to promote the emulsion stability and foaming ability and foam stability. This could be attributed to the alteration of the protein molecule configuration leading to the building of a rigid and viscoelastic protein film around the droplet. Copyright © 2006 Society of Chemical Industry     

On a generalized approach to manufacturing energy efficiency

Energy efficiency has become a very significant factor, requiring its inclusion in the manufacturing decision-making attributes. This paper proposes a generalized approach to manufacturing energy efficiency. The basic element of the approach is the division of energy efficiency definition and study into four manufacturing levels, namely process, machine, production line, and factory. Process-level definitions are provided for the majority of manufacturing processes. A machine-level study indicates and solves difficulties, generated by the workpiece geometry, and points out the interaction with the process level through factors, such as the process time. Moreover, machine tool peripherals are responsible for a significant portion of the consumed energy, and classification based on the dependence of their consumption on process variables is required. Studies made on the production line and factory levels show that energy efficiency, at these levels, is heavily dependent on production planning and scheduling and can be improved through the appropriate utilization of machines, with the inclusion of shutdown and eco-modes. Finally, a case study is presented, showing that many of the difficulties towards the optimization of energy efficiency can be dealt with successfully, using the proposed generalized approach.     

Development of a comprehensive mathematical model for free radical suspension polymerization of methyl methacrylate

In this work a detailed mathematical model for free radical suspension polymerization of methyl methacrylate (MMA) in water is developed. This model is based on sound principles such as the free volume theory to account for the diffusion limited reactions in suspension polymerization. Additionally, the complex polymerization kinetics process of the aqueous suspension polymerization of MMA is studied as a one‐dimensional numerical experiment. For this purpose, the polymerization process is modeled as a moving boundary mass transfer problem coupled with polymerization reactions. The Galerkin finite element method is used to simultaneously solve the nonlinear governing equations. The model predictions for conversion and average molecular weights vs. time were found to be in close agreement with laboratory data. It is believed that this work, as it provides fundamental understanding of the process, it might contribute to a more rational design of polymerization reactors. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Tuning the Stability of Graphene Layers by Phthalocyanine‐Based oPPV Oligomers Towards Photo‐ and Redoxactive Materials

In contrast to pristine zinc phthalocyanine (1), zinc phthalocyanine based oPPV‐oligomers (2–4) of different chain lengths interact tightly and reversibly with graphite, affording stable and finely dispersed suspensions of mono‐ to few‐layer graphene—nanographene (NG)—that are photoactive. The p‐type character of the oPPV backbones and the increasing length of the oPPV backbones facilitate the overall π–π interactions with the graphene layers. In NG/2, NG/3, and NG/4 hybrids, strong electronic coupling between the individual components gives rise to charge transfer from the photoexcited zinc phthalocyanines to NG to form hundreds of picoseconds lived charge transfer states. The resulting features, namely photo‐ and redoxactivity, serve as incentives to construct and to test novel solar cells. Solar cells made out of NG/4 feature stable and repeatable photocurrent generation during several ‘on‐off’ cycles of illumination with monochromatic IPCE values of around 1%.     

Physical characterization of thermally induced networks of lupin protein isolates prepared by isoelectric precipitation and dialysis

Summary Protein isolates of Lupinus albus were obtained from full fat and defatted lupin flour using isoelectric precipitation or dialysis. Calorimetric tests demonstrated that the main protein fractions of the isolates denature well below 100 °C. Mechanical spectra of isolate dispersions obtained at 80 °C indicated the formation of a 'pseudogel' whose cohesion increased during cooling to 10 °C. Subsequent heating to 90 °C encouraged extensive formation of disulphide bonds as it produced gels that were insoluble in sodium dodecyl sulphate and urea solutions. Dialysis produced isolates of lower gelling concentrations, which also formed networks of a stronger relative elastic character. The presence of NaCl at concentrations up to 0.5 m had a reinforcing effect on networks. Protein over-aggregation caused the opposite effect at higher salt levels. Finally, a comparison with results in the literature on soybean protein gelation suggested similar denaturation temperatures and a common pattern of structure formation for the two legume proteins.