In situ Characterization of SiO2 Nanoparticle Biointeractions Using BrightSilica

By adding a gold core to silica nanoparticles (BrightSilica), silica‐like nanoparticles are generated that, unlike unmodified silica nanoparticles, provide three types of complementary information to investigate the silica nano‐biointeraction inside eukaryotic cells in situ. Firstly, organic molecules in proximity of and penetrating into the silica shell in live cells are monitored by surface‐enhanced Raman scattering (SERS). The SERS data show interaction of the hybrid silica particles with tyrosine, cysteine and phenylalanine side chains of adsorbed proteins. Composition of the biomolecular corona of BrightSilica nanoparticles differs in fibroblast and macrophage cells. Secondly, quantification of the BrightSilica nanoparticles using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) micromapping indicates a different interaction of silica nanoparticles compared to gold nanoparticles under the same experimental conditions. Thirdly, the metal cores allow the investigation of particle distribution and interaction in the cellular ultrastructure by cryo nanoscale X‐ray tomography (cryo‐XT). In 3D reconstructions the assumption is confirmed that BrightSilica nanoparticles enter cells by an endocytotic mechanism. The high SERS intensities are explained by the beneficial plasmonic properties due to agglomeration of BrightSilica. The results have implications for the development of multi‐modal qualitative and quantitative characterization in comparative nanotoxicology and bionanotechnology.     

A comprehensive approach to the analysis of contrast enhanced cardiac MR images

Current magnetic resonance imaging (MRI) technology allows the determination of patient-individual coronary tree structure, detection of infarctions, and assessment of myocardial perfusion. Joint inspection of these three aspects yields valuable information for therapy planning, e.g., through classification of myocardium into healthy tissue, regions showing a reversible hypoperfusion, and infarction with additional information on the corresponding supplying artery. Standard imaging protocols normally provide image data with different orientations, resolutions and coverages for each of the three aspects, which makes a direct comparison of analysis results difficult. The purpose of this work is to develop methods for the alignment and combined analysis of these images. The proposed approach is applied to 21 datasets of healthy and diseased patients from the clinical routine. The evaluation shows that, despite limitations due to typical MRI artifacts, combined inspection is feasible and can yield clinically useful information.     

Sensitivity to signal quantization of 43 Gb/s and 107 Gb/s optical 16-QAM OFDM transmission with coherent detection

The sensitivity of optical orthogonal-frequency division multiplexing (OFDM) transmission to the finite resolutions of the digital-to-analog (DAC) and analog-to-digital converters (ADC) has been analyzed using numerical simulations. We show that for back-to-back configuration the requirements regarding the number of quantization bits for the DACs are similar to the ones of the ADCs. After transmission over metro and long-haul distances a higher resolution of the DAC/ADC is required compared to back-to-back configuration. We show that after transmission it is sufficient to enhance either the ADC resolution or the DAC resolution by 1 bit.     

Disruption tolerant networking by Smart Caching

Future mobile radio networks will aim at achieving ‘broadband access for all’, anywhere. The performance of a radio network vitally depends on the characteristics of the transmission path between the user terminal and the access point and the degree of network coverage. In urban areas, full broadband radio coverage is difficult to provide, causing a high variation in the link quality and making broadband services hard to realize. In rural regions, massive deployment costs prevent a full broadband coverage. Most of the time users have to settle for UMTS‐like wide area networks. For mobile users accessing services, such as video streaming, which require continuous broadband connectivity, it virtually results in intermittent network connectivity. The frequent disruption of the broadband link and its replacement with no or only low‐performance connections is a problem that should be addressed. This article introduces a new technique called Smart Caching (SC), which is able to mitigate variations in the network performance so that non‐real‐time and non‐interactive services' quality is substantially improved. SC supports pre‐fetching from a server and buffering data at the edge of the core network, in the so‐called Smart Cache. It transmits data with extremely high speed to be buffered in the mobile terminal when it is in the service range of an access point. This allows for the provisioning of data‐intensive services even in the case of patchy wireless broadband network coverage and intermittent connectivity. The performance of the SC service is evaluated with two different sophisticated queuing models, both based on the Markov arrival process. The benefit of the new technique is discussed and dimensioning issues are outlined. Furthermore, a comparison with legacy network setups is given. Copyright © 2009 John Wiley & Sons, Ltd.     

30-40-GHz drain-pumped passive-mixer MMIC fabricated on VLSI SOI CMOS technology

In this paper, a passive down mixer is proposed, which is well suited for short-channel field-effect transistor technologies. The authors believe that this is the first drain-pumped transconductance mixer that requires no dc supply power. The monolithic microwave integrated circuit (MMIC) is fabricated using digital 90-nm silicon-on-insulator CMOS technology. All impedance matching, bias, and filter elements are implemented on the chip, which has a compact size of 0.5 mm/spl times/0.47 mm. The circuit covers a radio frequency range from 30 to 40 GHz. At a RF frequency of 35 GHz, an intermediate frequency of 2.5 GHz and a local-oscillator (LO) power of 7.5 dBm, a conversion loss of 4.6 dB, a single-sideband (SSB) noise figure (NF) of 7.9 dB, an 1-dB input compression point of -6 dBm, and a third-order intercept point at the input of 2 dBm were measured. At lower LO power of 0 dBm, a conversion loss of 6.3 dBm and an SSB NF of 9.7 dB were measured, making the mixer an excellent candidate for low power-consuming wireless local-area networks. All results include the pad parasitics. To the knowledge of the authors, this is the first CMOS mixer operating at millimeter-wave frequencies. The achieved conversion loss is even lower than for passive MMIC mixers using leading edge III/V technologies, showing the excellent suitability of digital CMOS technology for analog circuits at millimeter-wave frequencies.     

HIAWSC： An Immune Algorithm Based Heuristic Web Service Composition Framework

The introduction of of web services has led to web service composition being a focus of many researchers. Composing web services using workflows is seen as the most realistic method from an industrial viewpoint. Amongst other method, the use of natural computing methods has been proposed previously to automate web service composition. The need for a fast response when computing the most suitable sequence of services is addressed in this paper. In particular, we propose a novel heuristic immune algorithm with an efficient encoding and mutation method. The algorithm involves two steps： an immune selection operation, which is maintaining antibody population diversity and the clonal selection. The use of a vaccine during the evolution provides heuristic information that accelerates the convergence. Our experimental results illustrate that the proposed heuristic immune algorithm is very effective in improving the convergence speed. We also provide a schema analysis for this method.     

The E3 architecture: enabling future cellular networks with cognitive and self‐x capabilities

Future mobile networks are expected to be complex heterogeneous systems. On the one hand this will enable users to take advantage of a number of different access technologies. On the other hand it will seriously affect network management procedures since more extensive operations and decisions will have to be dealt with. To tackle these challenges a number of new dynamic mechanisms need to be designed. It is imperative that certain network management tasks have to be performed without human intervention to reduce the OPEX costs and achieve faster responses in different events. To achieve this goal, the introduction of self‐x functionalities, combined with cognitive mechanisms and the ability to reconfigure network entities and terminals, is required. Moreover, the introduction of a new pilot channel needs to be considered to assist the terminals in selecting the most suitable radio access technology according to their requirements. We present the functional architecture of an evolved network that was designed in the context of the EU‐funded IP project ‘E³: End‐to‐End Efficiency’. This architecture aims to enhance existing procedures usually performed in traditional operation and maintenance systems (e.g. spectrum management, network planning, configuration actions). We explain the rationale of our design and provide specific examples to illustrate the role of the different functional entities and their interfaces. A considerable part of this architecture has recently been approved as a feasibility study by the ETSI Committee Reconfigurable Radio System. Copyright © 2010 John Wiley & Sons, Ltd.     

Morphology Transformation Pathway of Block Copolymer-Directed Cooperative Self-Assembly of ZnO Hybrid Films Monitored In Situ during Slot-Die Coating

Cooperative self-assembly (co-assembly) of diblock copolymers (DBCs) and inorganic precursors that takes inspiration from the rich phase separation behavior of DBCs can enable the realization of a broad spectrum of functional nanostructures with the desired sizes. In a DBC assisted sol–gel chemistry approach with polystyrene-block-poly(ethylene oxide) and ZnO, hybrid films are formed with slot-die coating. Pure DBC films are printed as control. In situ grazing-incidence small-angle X-ray scattering measurements are performed to investigate the self-assembly and co-assembly process during the film formation. Combining complementary ex situ characterizations, several distinct regimes are differentiated to describe the morphological transformations from the initially solvent-dispersed to the ultimately solidified films. The comparison of the assembly pathway evidences that the key step in the establishment of the pure DBC film is the coalescence of spherical micelles toward cylindrical domains. Due to the presence of the phase-selective precursor, the formation of cylindrical aggregates in the solution is crucial for the structural development of the hybrid film. The pre-existing cylinders in the ink impede the domain growth of the hybrid film during the subsequent drying process. The precursor reduces the degree of order, prevents crystallization of the PEO block, and introduces additional length scales in the hybrid films.     

Chemical vapor deposition synthesis of self-aligned carbon nanotube arrays

A procedure for producing arrays of self-aligned carbon nanotubes (CNTs) using standard chemical vapor deposition (CVD) is reported. Using UV photolithography, silicon substrates are patterned with a thin layer of thermally evaporated iron as a CNT catalyst. The CVD synthesis was carried out over a small temperature range (700°C–800°C) using acetylene and methane gasses, producing aligned CNT towers. Scanning electron microscopy (SEM) analysis shows a relationship between CNT tower height and synthesis time. Additionally, results show that impurity particles dramatically effect CNT tower growth. These results indicate that aligned CNTs can be produced in a desired pattern with height control.