Catalyst patterning methods for surface-bound chemical vapor deposition of carbon nanotubes

We present three different catalyst preparation and patterning techniques for plasma-enhanced chemical vapor deposition of carbon nanostructures from acetylene and ammonia mixtures. The different merits and potential areas of application are highlighted for each technique as compared to the benchmark of e-beam-lithography patterning. Maskless, focused ion beam written Pt can nucleate aligned carbon nanofibers, thereby allowing a sub-100 nm lateral resolution on non-planar substrate geometries combined with an in-situ monitoring. Ion beam milling additionally enables the pre-shaping and marking of the substrate, which is shown for the growth of individual nanofibers on the apex of commercial scanning probe tips. Pulsed electrochemical deposition was used to form Ni and Fe catalyst islands of controlled size and density. This is also demonstrated on complex substrate geometries such as carbon cloth. Nanocontact printing was employed to deposit a highly purified Co colloid in regular patterns with feature sizes down to 100 nm onto silicon wafers for low cost patterning over large areas. We analyze the catalyst restructuring upon exposure to elevated temperatures for each technique and relate this to the nucleated nanofiber dimensions and array densities. The flexibility in catalyst and substrate material allows a transfer of our achievements to catalyst-assisted growth of nanostructures in general facilitating their hierarchical device integration and future application. PACS 81.16.Rf; 81.16.Hc; 61.46.+w     

基于NbN，AIN技术的体声波器件研究

体声波滤波器由于其低插损、小尺寸、高带外抑制等特性，随着第三代移动通信以及蓝牙技术的发展而得到广泛研究，而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能．我们以单晶MgO作为器件衬底，MgO/NbN多层结构作为AIN薄膜体声波器件的反射器，NBN／AIN／NbN三层结构为谐振器．在这样的多层结构的设计中由于各种材料之间的晶格失配小，可以获得从几十纳米到几百纳米厚度不等的单晶AIN薄膜．通过控制AIN薄膜和NbN薄膜的不同厚度，可以获得不同频段范围的谐振器．压电薄膜的质量，以及体声波在多层结构界面上的能量损耗，直接影响到谐振器电学性能．基于AIN材料的压电性能，设计了NBN／AIN／NBN三层结构的谐振器，并进行了数值模拟．     

Optically detected electrophonon resonance effects in quantum wells

Optical detected electrophonon resonance (ODEPR) effects in quantum wells of n-GaAs materials are investigated for square potential and parabolic potential, respectively. We also obtain the ODEPR conditions as functions of confinement frequency in parabolic potential and well-width in square potential for the various photon frequencies, respectively. In particular, anomalous behaviors of the ODEPR lineshape such as the splitting of ODEPR peaks for incident photon frequency are discussed. Furthermore, we obtain the selection rules for transition in quantum wells of two different potentials, respectively.     

Simultaneous Analysis of Phosphorylated Peptides by MALDI-TOF-MS

Six peptides with various phosphorylation sensitivities for protein kinase A (PKA) were used for the simultaneous analysis of phosphorylated peptides using matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry. The mixture of six peptides was reacted with PKA and was analyzed by MALDI-TOF mass spectrometry. The intensity of all peaks except one phosphorylated peptide peak was very low (<20%). Moreover, we examined whether the addition of diammonium citrate to CHCA matrix at concentrations of 1–20 mg mL^?1 can increase the peak intensity of peptides and phosphorylated peptides. The addition of diammonium citrate increased the peak intensity of peptides and phosphorylated peptides, but an increase in the intensity was unsatisfactory. Our study strongly suggests that MALDI-TOF mass spectrometry is not suitable for the simultaneous analysis of phosphorylated peptides.     

Bidirectional WDM Self-Healing Ring Network for Hub/Remote Nodes

We demonstrate a bidirectional WDM self-healing ring network for hub/remote nodes with one fiber. In this network, self-healing can be achieved within 8 ms. The transmission capacity can be doubled in the operating state.     

Path Collapse for an Inhomogeneous Random Walk

On an open interval we follow the paths of a Brownian motion which returns to a fixed point as soon as it reaches the boundary and restarts afresh indefinitely. We determine that two paths starting at different points either cannot collapse or they do so almost surely. The problem can be modelled as a spatially inhomogeneous random walk on a group and contrasts sharply with the higher dimensional case in that if two paths may collapse they do so almost surely.     

Convergence and stability of the finite difference scheme for nonlinear parabolic systems with time delay

In this article, a class of nonlinear evolution equations – reaction–diffusion equations with time delay – is studied. By combining the domain decomposition technique and the finite difference method, the results for the existence, convergence and the stability of the numerical solution are obtained in the case of subdomain overlap and when the time-space is completely discretized. This revised version was published online in June 2006 with corrections to the Cover Date.     

Right Spread序的若干封闭性质

§1Introductionandmotivation Itisalwaysofinteresttocomparethevariabilityoftworandomvariablesinreliability theoryandeconomics.Thecomparisonsbasedonmomentssuchasvarianceandstandard deviationarenotveryinformativealthoughsuchmeasuresaresimpletouse.Meanwhile,sincethesecomparisonsarestaticones,andhencetheirapplicationsinsomefields,e.g.,reliabilityandfinance,arerestricted.Inthesefields,however,somedynamicalcomparisons areneeded.Asaresult,severalstochasticordersthataremorerefinedhavebeen establishedi…     

Use of Cu dopant and it's doping effects on polyaniline conducting system in water and tetrahydrofuran

The structural modification and properties of polymeric materials are of utmost importance in deciding their applications. In the present study, the synthesis of polyaniline (PANI) has been carried out via chemical oxidation in acidic medium by potassium-dichromate and the yield of synthesized polyaniline was found to be 75-80%. The copper per chlorate tetrabenzonitrile salt (CuClO₄·4BN) used for chemical doping in synthesized polyaniline is stable in organic solvent like acetonitrile (AN) and benzonitrile (BN). The effect of Cu⁺¹ oxidation state (dopant) in polyaniline has been characterized by FTIR. Electrical and dielectric measurements show the decrease in the intensity of the Cu⁺¹ salt signal and the appearance of a radical signal due to the formation of oxidative coupled in polymeric species. Electrical and dielectric properties of doped polyaniline samples show significant changes due to the effect of dopant (CuClO₄·4BN). It is observed that the conductivity is contributing both by formation of ionic complex and particularly dominated by electronic due to the mobility of charge carriers along the polyaniline chain.     

弱噪声极限下二维布朗运动的随机共振现象

在弱噪声极限下，应用多维Fokker-Planck方程的与时间有关问题方面的理论，推导了对称双稳势阱中二维布朗粒子的概率跃迁速率，并基于绝热近似理论研究了弱噪声极限下受小幅低频周期力驱动的二维布朗运动的随机共振现象.与以前的结果相比，所得到的信噪比与阻尼系数的大小无关.精确的数值模拟结果进一步说明了所得的信噪比的适用性. 关键词： 二维布朗运动 弱噪声极限 随机共振 信噪比