Nonlinear propagation model for ultrasound hydrophones calibration in the frequency range up to 100 MHz

To facilitate the implementation and verification of the new ultrasound hydrophone calibration techniques described in the companion paper (somewhere in this issue) a nonlinear propagation model was developed. A brief outline of the theoretical considerations is presented and the model's advantages and disadvantages are discussed. The results of simulations yielding spatial and temporal acoustic pressure amplitude are also presented and compared with those obtained using KZK and Field II models. Excellent agreement between all models is evidenced. The applicability of the model in discrete wideband calibration of hydrophones is documented in the companion paper somewhere in this volume.     

Spin accumulation and domain wall magnetoresistance in 35 nm Co wires

An enhancement of the resistance due to the presence of only one or two isolated domain walls is clearly evidenced by transport measurements in 35 nm epitaxial Co wires, 20 &mgr;m long. The deduced relative change in the resistivity is at least 1 order of magnitude larger than the one predicted from a model based on the mixing of spin channels occurring over the length scale of the domain wall width [P. M. Levy and S. Zhang, Phys. Rev. Lett. 79, 5110 (1997)]. This inconsistency can be resolved by taking the effect of spin accumulation into account, which scales in the case of Co over the much larger distance of the spin diffusion length.     

A phase I, randomized study of combined IL-2 and therapeutic immunisation with antiretroviral therapy

Background  

Fully functional HIV-1-specific CD8 and CD4 effector T-cell responses are vital to the containment of viral activity and disease progression. These responses are lacking in HIV-1-infected patients with progressive disease. We attempted to augment fully functional HIV-1-specific CD8 and CD4 effector T-cell responses in patients with advanced chronic HIV-1 infection.     

Microstructure and morphology of self‐assembling multiblock poly(ethylene‐1‐butene)‐n copolymers in solution studied by wide‐Q small‐angle neutron scattering and microscopy

Multiblock ethylene‐1‐butene copolymers (PEB‐n) with graded ethylene content (where n is the number of ethyl branches per 100 backbone carbons) represent efficient cold filter plugging point (CFPP) depressants for crude oils and middle distillates. The aggregation behavior and the interaction with wax molecules of a tetrablock PEB‐2.6/PEB‐6.0/PEB‐10.9/PEB‐13.2 and triblock PEB‐6.5/PEB‐8.9/PEB‐10.1 copolymers in decane solutions were investigated over a wide temperature range by combining different small‐angle neutron scattering techniques and optical microscopy. The experimental results revealed in the decrease of temperature formation and evolution of multisized structural levels showing a hierarchical organization on the length scale from 1 nm up to 10 μm. One‐dimensional polymer aggregates arising as initial structures associate and branch that lead to the occurrence of complex macroaggregates with diffusive interfaces and sizes of several microns. The one‐dimensional copolymer structure shows longitudinal density modulation and micellar‐like substructures in neat polymer solutions. When wax is added, this structure becomes more homogeneous in decrease of temperature as a consequence of the cocrystallization of wax and copolymer. The wax crystallization in board‐like objects of much smaller size than required by the CFPP criterion of oil and refinery industry (filter mesh size of 45 μm) is templated and controlled by the assembling features of the crystalline–amorphous PEB‐n multiblock copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Shear banding in reaction-diffusion models

Shear banding occurs in the flow of complex fluids: various types of shear thinning and shear thickening micelle solutions and liquid crystals. In order to cope with the strongly inhomogeneous interface between the bands, constitutive models used in standard rheology must be supplemented by non-local terms. This leads rather generally to non-linear partial differential equations of the reaction-diffusion type. We use this formalism in order to explain some observed experimental features and as a guide for future research in this field. Received: 17 May 1999/Accepted: 3 August 1999     

The best quadrature formula based on Hermite information for the class KW~2[a,b]

The best quadrature formula has been found in the following sense:for afunction whose norm of the second derivative is bounded by a given constant and thebest quadrature formula for the approximate evaluation of integration of that function canminimize the worst possible error if the values of the function and its derivative at certainnodes are known.The best interpolation formula used to get the quadrature formula aboveis also found.Moreover,we compare the best quadrature formula with the open compoundcorrected trapezoidal formula by theoretical analysis and stochastic experiments.     

Effect of boundary layer losses on 2D detonation cellular structures

We evaluate the effect of boundary layer losses on two-dimensional H2/O2/Ar cellular detonations obtained in narrow channels. The experiments provide the details of the cellular structure and the detonation speed deficits from the ideal CJ speed. We model the effect of the boundary layer losses by incorporating the flow divergence in the third dimension due to the negative boundary layer displacement thickness, modeled using Mirels’ theory. The cellular structures obtained numerically with the resulting quasi-2D formulation of the reactive Euler equations with two-step chain-branching chemistry are found in excellent agreement with experiment, both in terms of cell dynamics and velocity deficits, provided the boundary layer constant of Mirels is modified by a factor of 2. A significant increase in the cell size is found with increasing velocity deficit. This is found to be very well captured by the induction zone increase in slower detonations due to the lower temperatures in the induction zone.     

静电陀螺仪MUM小角度读取的相关技术研究

讨论了同步解调法实现静电陀螺仪质量不平衡调制（MUM，Mass-Unbalanced Modulation）小角度读取的原理，分析了影响读取分辨率的各种因素，并对其实施方案中的相关技术进行了探讨。研究表明，尽管MUM读取方案非常适用于实心转子静电陀螺仪，但前提是将其小角度读取的分辨率提高到可与光电方法相比的水平（角秒级）。要实现这一目标，首先要保证转子和电极的机械特性达到一定要求；在此基础上，还要在支承系统的结构、转子位移测量电路设计等方面进行精心设计。     

Amperometric Hydrogen Peroxide Biosensor Based on Multiwall Carbon Nanotubes and Cadmium Sulfide Quantum Dots

<正>A novel third-generation hydrogen peroxide(H_2O_2) biosensor(Hb/CdS/MWNTs/GCE) was fabricated through hemoglobin(Hb) adsorbed onto the mercaptoacetic acid modified CdS QDs/carboxyl multiwall carbon nanotubes'(MWNTs) films.Cyclic voltammogram of Hb/CdS/MWNTs/GCE showed a pair of well-defined and quasi-reversible redox peaks with a formal potential(E~0) of-0.230 V(vs.Ag/AgCl) in 0.1 mol/L pH=8.0 phosphate buffer solution(PBS),which was the characteristic of the Hb heme Fe(Ⅲ)/Fe(Ⅱ) redox couple.The biosensor shows an excellent electrocatalytic activity to the reduction of H_2O_2.The response time of the designed biosensor to H_2O_2 at a potential of -0.30 V was less than 2 s and linear relationships were obtained in the concentration ranges of 2.0×10~(-6)—2.7×10~(-3) mol/L and 2.7×10~(-3)—7.7×10~(-3) mol/L with a detection limit of 3.0×10~(-7)mol/L(S/N=3).The apparent Michaelis-Menten constant K_m was estimated to be 1.324 mmol/L that illustrated the excellent biological activity of the fixed Hb.     

Fe-ZSM-5 分子筛催化剂上N2O一步氧化苯制苯酚的积炭动力学

 采用等温固定床反应器和热重分析相结合的方法研究了 Fe-ZSM-5 分子筛上 N2O 一步氧化苯制苯酚的积炭行为, 考察了反应时间、温度和原料配比对积炭量的影响. 依据实验现象和积炭物组分分布的气相色谱-质谱分析结果, 提出了 Fe-ZSM-5 分子筛上 N2O 一步氧化苯制苯酚的积炭机理. 结果表明, Fe-ZSM-5 分子筛上的积炭物种主要来源于氧化产物苯酚的深度氧化, 属连串失活. 基于所提出的积炭机理和实验结果, 建立了 Fe-ZSM-5 分子筛催化剂的积炭动力学模型, 统计检验和残差分布检验表明, 所建模型与实验结果相容, 可靠性强.