Coadsorption of water and CO molecules on Ru(0 0 1) at high CO coverages: comparisons with a Ru(0 0 1) electrode surface

The coadsorption of carbon monoxide (CO) and water molecules on a Ru(0 0 1) surface has been studied by infrared spectroscopy, LEED and STM. At high CO coverage phases, a 2×2-(2CO+D₂O) structure was observed on both UHV and electrode surfaces. Electrode potential dependent structures from CO and water adlayers on an electrode surface were reproduced on a UHV surface by controlling molecular orientations of the first layer and second over-layer water molecules. At lower CO coverages, a CO band center showed coverage dependent shift down to 1444 cm⁻¹ due to an electron transfer from a lone pair of a water molecule to CO 2π^*.     

磁致伸缩材料弱磁场响应特性的实验研究

针对磁致伸缩材料在弱磁场传感器领域的应用需要,采用迈克耳逊干涉原理实验测量了零应力条件下Tb-Dy-Fe材料和Fe-Ga合金的磁场响应灵敏度,以及不同应力下Fe-Ga合金的磁场响应特性和温度响应特性.实验结果表明：在零应力,外加磁场16 mT条件下,Fe-Ga合金的磁场响应灵敏度远高于Tb-Dy-Fe材料,更合适作为弱磁场传感器敏感材料;同时,在1.2 MPa预应力和26 mT偏置磁场下,Fe-Ga合金材料具有较好的磁场响应灵敏度和较大的饱和磁致伸缩系数,因而处在最佳工作状态.所得到的材料的磁场和温度响应曲线可作为弱磁场传感器参量设计的参考依据.     

Study on the denoising method for the electromagnetic ultrasonic echoes from multiple interfaces

The electromagnetic ultrasound is used in the detection of interfaces of the adhesive multilayer structures to solve the unstable coupling problem in ultrasonic testing by traditional piezoelectric transducers. Based on the analysis of the transforming mechanism of electromag-netic ultrasound energy and the resultant dead zone from mutual inductance of the transducer, the wavelet filtering by soft-thresholding and adaptive noise canceling methods are used simul-taneously to the detected electromagnetic ultrasonic signals to overcome the drawbacks of the low signal to noise ratio （SNR） and the wide intrinsic dead zone of the transducer. Processed results in the interface detection of a three layered adhesive sample of steel and rubber materials demonstrate that the wavelet filtering enhances the SNR about 12dB while the adaptive noise canceling narrows the dead zone effectively.     

Mathematical Analysis of a PDE System for Biological Network Formation

Motivated by recent physics papers describing rules for natural network formation, we study an elliptic-parabolic system of partial differential equations proposed by Hu and Cai [13 Hu , D. (2013). Optimization, Adaptation, and Initialization of Biological Transport Networks. Workshop on multiscale problems from physics, biology and material sciences. May 28–31st, 2014, Shanghai. Available at: http://math.sjtu.edu.cn/conference/multiscale2014/ (accessed 6 January 2015). [Google Scholar], 15 Hu , D. , Cai , D. ( 2013 ). Adaptation and optimization of biological transport networks . Phys. Rev. Lett. 111 : 138701 .[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. The model describes the pressure field thanks to Darcy's type equation and the dynamics of the conductance network under pressure force effects with a diffusion rate D ≥ 0 representing randomness in the material structure. We prove the existence of global weak solutions and of local mild solutions and study their long term behavior. It turns out that, by energy dissipation, steady states play a central role to understand the network formation capacity of the system. We show that for a large diffusion coefficient D, the zero steady state is stable, while network formation occurs for small values of D due to the instability of the zero steady state, and the borderline case D = 0 exhibits a large class of dynamically stable (in the linearized sense) steady states.     

Well/Ill Posedness for the Euler-Korteweg-Poisson System and Related Problems

We consider a general Euler-Korteweg-Poisson system in R ³, supplemented with the space periodic boundary conditions, where the quantum hydrodynamics equations and the classical fluid dynamics equations with capillarity are recovered as particular examples. We show that the system admits infinitely many global-in-time weak solutions for any sufficiently smooth initial data including the case of a vanishing initial density - the vacuum zones. Moreover, there is a vast family of initial data, for which the Cauchy problem possesses infinitely many dissipative weak solutions, i.e. the weak solutions satisfying the energy inequality. Finally, we establish the weak-strong uniqueness property in a class of solutions without vacuum. In this paper we show that, even in presence of a dispersive tensor, we have the same phenomena found by De Lellis and Székelyhidi.     

Synthesis,spectroscopic and crystal structure analysis of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)imidazo[2,1-b][1,3,4]thiadiazole and its morpholinomethyl derivative

The preparation of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)-5-morpholin-1-ylmethyl imidazo[2,1-b][1,3,4]thiadiazole via the intermediate 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)Imidazo[2,1-b][1,3,4] thiadiazole is described. Elemental analysis, IR spectrum, ¹H NMR and X-ray crystal structure analyses were carried out to determine the compositions and molecular structures of the two compounds. The crystal packing exhibits intermolecular C–H?O, C–H?N, C–H?F and π–π stacking interactions leading to the formation of the supramolecular network.     

Scanning Probe Microscopy beyond Imaging: A General Tool for Quantitative Analysis

A simple, fast and general approach for quantitative analysis of scanning probe microscopy (SPM) images is reported. As a proof of concept it is used to determine with a high degree of precision the value of observables such as 1) the height, 2) the flowing current and 3) the corresponding surface potential (SP) of flat nanostructures such as gold electrodes, organic semiconductor architectures and graphenic sheets. Despite histogram analysis, or frequency count (Fc), being the most common mathematical tool used to analyse SPM images, the analytical approach is still lacking. By using the mathematical relationship between Fc and the collected data, the proposed method allows quantitative information on observable values close to the noise level to be gained. For instance, the thickness of nanostructures deposited on very rough substrates can be quantified, and this makes it possible to distinguish the contribution of an adsorbed nanostructure from that of the underlying substrate. Being non‐numerical, this versatile analytical approach is a useful and general tool for quantitative analysis of the Fc that enables all signals acquired and recorded by an SPM data array to be studied with high precision.     

Equilibrium Topology and Partial Inversion of Janus Drops: A Numerical Analysis

The equilibrium topology of an aqueous Janus emulsion of two oils, O1 and O2, with water, W, [(O1+O2)/W], is numerically evaluated with the following realistic interfacial tensions (γ): γ_O2/W=5 mN m⁻¹, γ_O1/O2=1 mN m⁻¹, and γ_O1/W varies within the range 4–5 mN m⁻¹, which is the limiting range for stable Janus drop topology. The relative significance of the two independently pivotal factors for the topology is evaluated, that is, the local equilibrium at the line of contact between the three liquids and the volume fraction of the two dispersed liquids within the drop. The results reveal a dominant effect of the local equilibrium on the fraction of the O2 drop surface that is covered by O1. In contrast, for a constant volume of O2, the impact of the interfacial tension balance on the limit of the coverage is modest for an infinite volume of O1. Interestingly, when the O1 volume exceeds this value, an emulsion inversion occurs, and the O1 portion of the (O1+O2)/W topology becomes a continuous phase, generating a (W+O2)/O1 Janus configuration.