三值脉冲式JKL触发器设计

锁存器和触发器是时钟系统的基本元件.由于具有硬边沿、低延时等特点,脉冲式触发器比主从触发器越来越受到关注.很多文献对二值脉冲式触发器进行了研究,但是目前对三值CMOS脉冲式触发器的研究并不多.本文从脉冲式触发器的特点出发,提出了单边沿、双边沿三值脉冲式JKL触发器的设计,进一步丰富和完善了多值脉冲式触发器的设计.HSPICE模拟结果表明,提出的三值脉冲式JKL触发器具有正确的逻辑功能和功耗低、延时小的特点.与从传统的主从型和维持阻塞型三值JKL触发器相比,所设计的三值脉冲式JKL触发器电路结构简单,节省了近54.5%的能耗.     

Ultra‐Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein‐Rich Biomedia

Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface‐enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt‐induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time‐window of a few minutes. Here, we present an emulsion templated method which allows formation of densely‐packed quasi‐spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein‐rich bio‐solutions where conventional aggregated colloids fail.     

Inflation with hyperbolic potential in the braneworld model

In this paper we study inflationary dynamics with a scalar field in an inverse coshyperbolic potential in the braneworld model. We note that a sufficient inflation may be obtained with the potential considering slow-roll approximation in the high energy limit. We determine the minimum values of the initial inflaton field required to obtain sufficient inflation and also determine the relevant inflationary parameters. The numerical values of spectral index of the scalar perturbation spectrum are determined by varying the number of e-foldings for different initial values of the inflaton field. The result obtained here is in good agreement with the current observational limits.      

Raman and surface‐enhanced Raman studies of α‐aminophosphinic inhibitors of metalloenzymes

Here, we report the nature of new di‐α‐amino (L¹–L³) and α‐amino‐α‐hydroxyphosphinic (L⁴–L⁶) acids, which are considered potential inhibitors of the aminopeptidase N, adsorbed on a colloidal silver surface by means of surface‐enhanced Raman scattering (SERS) spectroscopy. In order to reveal the adsorption mechanism of these species from their SERS spectra, Fourier‐transform Raman (FT‐RS) spectra of these nonadsorbed molecules were measured. By examining the enhancement, shift in wavenumbers, and changes in breadth of the SERS bands due to the adsorption process, we revealed that the tilted compounds interact with the colloidal silver substrate mainly through the benzene ring, amino group, and phosphinic moiety in the following way. The benzene ring of L² and L³ is ‘standing up’ on the colloidal silver surface, and the C N bond is almost vertical to it, while the tilt angle between the O PO bond and this surface is greater than 45°. On the other hand, for L¹, L⁴, and L⁵, the aromatic ring and C N bond are arranged more or less tilted, and the tilt angle between the O PO bond and the silver substrate is smaller than 45°. The elongation of the bond to the benzene ring, the L⁶ case, produces an almost horizontal orientation of the benzene ring and the O PO bond on the silver nanoparticles. For these ligands, the complement inhibition IC₅₀ tested in vitro using porcine kidney leucine aminopeptidase was correlated mainly with the behavior of the O PO and C CH N fragments on the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison of adsorption mechanism on colloidal silver surface of alafosfalin and its analogs

This study reports the Raman (FT‐RS) and absorption infrared (FT‐IR) spectra, based on calculated wavenumbers and normal modes of vibrations, of the following compounds: L ‐Ala‐L ‐NH‐CH(Me)‐PO₃H₂ (alafosfalin, A1), L ‐Ala‐D ‐NH‐CH(Me)‐PO₃H₂ (A2), L ‐Ala‐L ‐NH‐CH(Et)‐PO₃H₂ (A3), D ,L ‐Ala‐D,L ‐NH‐CH(Et)‐PO₃H₂ (A4), L ‐Ala‐D ‐NH‐CH(iPr)‐PO₃H₂ (A5), L ‐Ala‐D,L ‐NH‐CH(iPr)‐PO₃H₂ (A6), L ‐Ala‐D,L ‐NH‐CH(tBu)‐PO₃H₂ (A7), L ‐Ala‐D,L ‐NH‐CH(iBu)‐PO₃H₂ (A8), L ‐Ala‐D,L ‐NH‐CH(cBu)‐PO₃H₂ (A9), L ‐Ala‐D,L ‐NH‐CH(nPA)‐PO₃H₂ (A10), β‐Ala‐D ‐NH‐CH(Me)‐PO₃H₂ (A11), and D,L ‐Ala‐NH‐C(Me,Me)‐PO₃H₂ (A12). The equilibrium geometries and vibrational wavenumbers are calculated using density functional theory (DFT) at the B3LYP; 6–31 + + G** level of theory using Gaussian'03, GaussSum 0.8, and GAR2PED software. We briefly compare and analyze the experimental and calculated vibrational wavenumbers in the range of 3600–400 cm⁻¹. In addition, Raman wavenumbers are compared to those from surface‐enhanced Raman scattering (SERS) for the phosphonodipeptides of alanine (Ala) adsorbed on a colloidal silver surface. The geometry of these molecules etched on the silver surface is deduce from the observed changes in both the intensity and breadth of Raman bands in the spectra of the bound vs free species. For example, A7, A8, A1, A3, and A4 appear to adsorb onto the colloidal silver particles mainly through the phosphonate terminus, and for A3 and A4, through the  C‐NH₂ and  CONH fragments. The most dominant SERS bands of A5, A6, A9, A10, and A11 are due to the amide bond vibrations, as well as to the vibrations of the  C‐NH₂ group (A9 and A10) and the C C group (A6 and A11). The differences recorded for the A5, A6, A9, A10, and A11 and those of A2 and A12 are due to interactions between the amine and methyl groups with the silver surface, and they reflect vibrational characteristic of these groups. Copyright © 2008 John Wiley & Sons, Ltd.     

Theory of lateral and flip-flop phase separations in bilayer biomembranes and surfactants

In this work, we consider bilayer biomembranes or surfactants made of two amphiphiles A and B. Under a variation of a suitable parameter, such as temperature or difference of lengths of hydrophobic chains, these systems undergo a phase separation from a homogeneous liquid-phase to two distinct liquid-phases. Two physical situations can be distinguished: (1) The amphiphiles A and B prefer to jump from a monolayer to the other (flip-flop transition), (2) the mixture phase separates on each monolayer, and there is no jump from one sheet towards the second one (lateral transition). To investigate the associated critical phase behavior, we first introduce a field theory, constructed with two order parameters (or fields) φ and ψ, which are nothing else but the composition fluctuations relative to the monolayers. Beside the usual terms proportional to φ², ψ², φ⁴ and ψ⁴, the free energy contains an extra one, −Cφψ, which describes the lowest order coupling between the two monolayers. The coupling constant C is positive for the lateral phase separation, and negative for the vertical one. We show that its sign results from a competition between the chemical segregation of amphiphiles and the curvature asymmetry. With the help of this free energy, we first identify the liquid-phases, and show the existence of a critical point, T_c, of which the location depends naturally on the value of the coupling constant C. In particular, for those bilayer biomembranes or surfactants made of amphiphiles of the same chemical nature but with different lengths, and at fixed temperature, we show the existence of a critical line in the -plane, along which the bilayer undergoes a phase separation. Here, and account for the curvature gap and the length difference, respectively. Second, we determine the behavior of the composition fluctuations, φ and ψ, and the total one, Φ=φ+ψ, upon temperature, T, and chemical potential difference, , in the critical region. Third, we determine the critical behavior of the partial compressibilities, κ_φφ, κ_ψψ and κ_φψ, and the overall one, . Finally, we remark that the flip-flop phase separation shows some analogy with the classical para-ferrimagnetic transition of coupled paramagnetic materials of Curie-Weiss type.     

基于低密度奇偶校验码的超强前向纠错码设计

光纤中的传输效应(如色散、偏振模色散(PMD)和非线性效应等)会严重影响传输速率和传输距离的进一步提高。因而有必要研究性能更好的新超强前向纠错(Super-FEC) 码型,使其在光通信系统中获得更高的编码增益和更好的纠错性能。简单介绍了低密度奇偶校验(LDPC)码, 然后提出光通信系统中一种基于LDPC码的超强前向纠错(Super-FEC)码型,构造了冗余度为6.68%的新颖LDPC(3969,3720)码, 并给出超强FEC码型的仿真结果。通过与RS(255,239)及BCH(3860,3824)+BCH(2040,1930)进行对比分析, 还分析与探讨了新LDPC码型的编译码电路的设计实现问题。通过理论分析与仿真结果表明这种超强 FEC 码型具有良好的性能, 可以节省硬件开销, 比较适用于光通信系统中, 可作为超强 FEC 码型的候选码。     

The vectorial angular-spectrum representation and Rayleigh–Sommerfeld diffraction formulae

The equivalence of the vectorial angular-spectrum representation and Rayleigh–Sommerfeld (RS) diffraction formulae is studied. Based on the angular-spectrum representation and the Weyl representation of a spherical wave, the vectorial RS diffraction formulae of the first and second kinds are derived in a simple way. Numercial results of diffracted divergent spherical waves are given to illustrate the application of the two vectorial RS diffraction formulae.     

Characterization of carbon nanotubes and analytical methods for their determination in environmental and biological samples: A review

In the present paper, a critical overview of the most commonly used techniques for the characterization and the determination of carbon nanotubes (CNTs) is given on the basis of 170 references (2000–2014). The analytical techniques used for CNT characterization (including microscopic and diffraction, spectroscopic, thermal and separation techniques) are classified, described, and illustrated with applied examples. Furthermore, the performance of sampling procedures as well as the available methods for the determination of CNTs in real biological and environmental samples are reviewed and discussed according to their analytical characteristics. In addition, future trends and perspectives in this field of work are critically presented.