Proposal for a novel and simple WDM NRZ-DPSK system

A novel and simple non-return-to-zero differential phase shift keying (NRZ-DPSK) wavelength division multiplexing (WDM) system, which can simultaneously demultiplex and demodulate multiple wavelengths, is proposed and investigated in this paper.The phase-to-intensity demodulation principle is based on detuned filtering, which is achieved by using a single commercial array waveguide grating (AWG) in our scheme.By properly choosing appropriate AWG channels at the transmitter, the AWG at the receiver can act as both the demultiplexer and the demodulator of the DPSK signals.Simulations at 10, 20, and 40 Gbit/s show good flexibility and performance for the proposed system.     

Non‐Covalent Functionalization of Graphene Using Self‐Assembly of Alkane‐Amines

A simple, versatile method for non‐covalent functionalization of graphene based on solution‐phase assembly of alkane‐amine layers is presented. Second‐order Møller–Plesset (MP2) perturbation theory on a cluster model (methylamine on pyrene) yields a binding energy of ≈220 meV for the amine–graphene interaction, which is strong enough to enable formation of a stable aminodecane layer at room temperature. Atomistic molecular dynamics simulations on an assembly of 1‐aminodecane molecules indicate that a self‐assembled monolayer can form, with the alkane chains oriented perpendicular to the graphene basal plane. The calculated monolayer height (≈1.7 nm) is in good agreement with atomic force microscopy data acquired for graphene functionalized with 1‐aminodecane, which yield a continuous layer with mean thickness ≈1.7 nm, albeit with some island defects. Raman data also confirm that self‐assembly of alkane‐amines is a non‐covalent process, i.e., it does not perturb the sp² hybridization of the graphene. Passivation and adsorbate n‐doping of graphene field‐effect devices using 1‐aminodecane, as well as high‐density binding of plasmonic metal nanoparticles and seeded atomic layer deposition of inorganic dielectrics using 1,10‐diaminodecane are also reported.     

Selection criteria for the analysis of data-driven clusters in cerebral FMRI

Functional MRI (fMRI) may be possible without a priori models of the cerebral hemodynamic response. First, such data-driven fMRI requires that all cerebral territories with distinct patterns be identified. Second, a systematic selection method is necessary to prevent the subjective interpretation of the identified territories. This paper addresses the second point by proposing a novel method for the automated interpretation of identified territories in data-driven fMRI. Selection criteria are formulated using: 1) the temporal cross-correlation between each identified territory and the paradigm and 2) the spatial contiguity of the corresponding voxel map. Ten event-design fMRI data sets are analyzed with one prominent algorithm, fuzzy c-means clustering, before applying the selection criteria. For comparison, these data are also analyzed with an established, model-based method: statistical parametric mapping. Both methods produced similar results and identified potential activation in the expected territory of the sensorimotor cortex in all ten data sets. Moreover, the proposed method classified distinct territories in separate clusters. Selected clusters have a mean temporal correlation coefficient of 0.39+/-0.07 (n=19) with a mean 2.7+/-1.4 second response delay. At most, four separate contiguous territories were observed in 87% of these clusters. These results suggest that the proposed method may be effective for exploratory fMRI studies where the hemodynamic response is perturbed during cerebrovascular disease.     

Facile Synthesis of Red/NIR AIE Luminogens with Simple Structures,Bright Emissions,and High Photostabilities,and Their Applications for Specific Imaging of Lipid Droplets and Image‐Guided Photodynamic Therapy

Red/near‐infrared (NIR) fluorescent molecules with aggregation‐induced emission (AIE) characteristics are of great interest in bioimaging and therapeutic applications. However, their complicated synthetic approaches remain the major barrier to implementing these applications. Herein, a one‐pot synthetic strategy to prepare a series of red/NIR‐emissive AIE luminogens (AIEgens) by fine‐tuning their molecular structures and substituents is reported. The obtained AIEgens possess simple structures, good solubilities, large Stokes shifts, and bright emissions, which enable their applications toward in vitro and in vivo imaging without any pre‐encapsulation or ‐modification steps. Excellent targeting specificities to lipid droplets (LDs), remarkable photostabilities, high brightness, and low working concentrations in cell imaging application make them remarkably impressive and superior to commercially available LD‐specific dyes. Interestingly, these AIEgens can efficiently generate reactive oxygen species upon visible light irradiation, endowing their effective application for photodynamic ablation of cancer cells. This study, thus, not only demonstrates a facile synthesis of red/NIR AIEgens for dual applications in simultaneous imaging and therapy, but also offers an ideal architecture for the construction of AIEgens with long emission wavelengths.     

In-Plane Coupling of Light From InP-Based Photonic Crystal Band-Edge Lasers Into Single-Mode Waveguides

In this paper, we analyze the coupling of light from photonic-crystal band-edge lasers into single-mode waveguides. Both active and passive devices lie in the same plane and coupling of light is achieved by using parabolic and nanotapers in InP based epitaxial structures. Two- and three-dimensional finite-difference time-domain methods are employed to analyze these devices. Coupling efficiencies higher than 80% can be obtained with parabolic couplers. We also present laser configurations that can reduce multiwavelength coupling of light into single-mode waveguides, using structures that are similar to coupled cavity Fabry-Peacuterot lasers     

Bit error rate evaluation of linear equalization in FWA systems

The bit error rate performance of broadband wireless fixed access (FWA) systems over multipath fading channels is investigated in this paper. Linear MMSE equalization is examined theoretically for 16‐QAM and QPSK modulated FWA systems and shown to yield unsatisfactory performance. The theoretical analysis is validated by Monte‐Carlo simulations and proved to be reasonably accurate. It provides us an insight into the physical limitations imposed by the FWA channels and suggest solutions to improve the capacity and performance of future FWA systems. Copyright © 2006 John Wiley & Sons, Ltd.     

高级触摸感应技术普遍应用于玩家界面

正现在,消费性电子产品(最早是MP3播放器,现在则是智能手机、电子阅读器和平板电脑)上复杂精致的触摸屏互动应用日渐受到人们的青睐;它能使游戏机更加现代化,能吸引更年轻、更热衷高端技术的玩家。它能让玩家享受一系列功能和操作上的优势,同时使得开发商能够提供与其竞争对手截然不同的产品类型,在     

Modeling of spiking analog neural circuits using organic semiconductor thin film transistors with silicon oxide nitride semiconductor gates

This paper uses the results of the characterization of amorphous semiconductor thin film transistors (TFTs) with the quasi-permanent memory structure referred to as silicon oxide nitride semiconductor (SONOS) gates, to model spiking neural circuits. SONOS gates were fabricated and characterized. In addition, MOSFETs using organic copper phthalocyanine (CuPc) were fabricated with these SONOS gates to demonstrate proof of concept performance. Analog spiking circuits were then modeled using these low performance TFTs to demonstrate the general suitability of organic TFTs in neural circuits. The basic circuit utilizes a standard comparator with charge and discharge circuits. A simple Hebbian learning circuit was added to charge and discharge the SONOS device. The use of these elements allows for the design and fabrication of high-density 3-dimensional circuits that can achieve the interconnect density of biological neural systems.     

Fabricating Strong and Stiff Bioplastics from Whole Spirulina Cells

Since the 1950s, 8.3 billion tonnes (Bt) of virgin plastics have been produced, of which around 5 Bt have accumulated as waste in oceans and other natural environments, posing severe threats to entire ecosystems. The need for sustainable bio-based alternatives to traditional petroleum-derived plastics is evident. Bioplastics produced from unprocessed biological materials have thus far suffered from heterogeneous and non-cohesive morphologies, which lead to weak mechanical properties and lack of processability, hindering their industrial integration. Here, a fast, simple, and scalable process is presented to transform raw microalgae into a self-bonded, recyclable, and backyard-compostable bioplastic with attractive mechanical properties surpassing those of other biobased plastics such as thermoplastic starch. Upon hot-pressing, the abundant and photosynthetic algae spirulina forms cohesive bioplastics with flexural modulus and strength in the range 3–5 GPa and 25.5–57 MPa, respectively, depending on pre-processing conditions and the addition of nanofillers. The machinability of these bioplastics, along with self-extinguishing properties, make them promising candidates for consumer plastics. Mechanical recycling and fast biodegradation in soil are demonstrated as end-of-life options. Finally, the environmental impacts are discussed in terms of global warming potential, highlighting the benefits of using a carbon-negative feedstock such as spirulina to fabricate plastics.     

可编程定时器--终极定时解决方案

如今,通信、计算和先进消费型系统中的复杂设计越来越容易受到最后时刻的设计变更、性能要求的不断攀升以及相关标准演进的影响。设计师必须保持灵活性,以便能够将关键元件的选择推迟到开发过程的后期来进行。