一种新型硫酸亚铁单液法调剖剂

本文提出用尿素作为ｐⅡ调节剂，加快硫酸亚铁单液法调剖剂中亚铁离子在地层温度下的沉淀，增大沉淀率，提高封堵效能。岩芯流动试验结果表明，１５％ＦｅＳＯ４．７ＩＩ ２Ｏ／５％尿素调剖剂体系的封堵能力比不含尿素的体系增大近一倍。     

Beam propagation analysis for tapered waveguides: taking account ofthe curved phase-front effect in paraxial approximation

A novel equivalent waveguide theory based on the conformal mapping method is employed to investigate the tapered waveguide with curved phase fronts. By using the theory, the curved phase fronts of a tapered waveguide would be transformed into the planar ones of its equivalent straight-liked structure. Therefore, the paraxial beam propagation method can be used to analyze the equivalent structures of tapered waveguides (even for wide-angle tapers). Two kinds of popular tapered waveguides, including the cross-sectional dimension tapering and the constant V-number tapering, are used to analyze by our combination of conformal mapping method and beam propagation method (BPM)     

Durable electrochromic coatings prepared from electronically conductive poly(3HT-co-3TPP)-silica hybrid materials

In this paper, a series of organic-inorganic hybrid materials, consisting of heterocyclic conjugated poly(3-hexylthiophene), P3HT, network, and silica particles, were successfully prepared for electrochromic studies. First, the heterocyclic co-polymer of poly[3-hexylthiophene-co-N-(3-trimethoxysilylpropyl) pyrrole], P(3HT-co-3TPP), containing trimethoxysilyl functional groups in the co-polymer backbone as the sol-gel precursor were prepared by conventional oxidative polymerization. Subsequently, P(3HT-co-3TPP)-silica hybrid sol-gel materials in the form of coatings were prepared by baking the microslides and ITO-coated electrodes that had been cast with homogeneous blending solutions containing co-polymer, acid-dopant, tetraethyl orthosilicate (TEOS), and a few drops of water. The microstructures of silica particles formed in the P(3HT-co-3TPP)-silica hybrid materials were investigated by transmission electron microscopy (TEM). The as-prepared hybrid coatings had improved adhesion capability on inorganic glass substrates relative to the pure P3HT on the basis of electrochemical cyclic voltammetric studies and Scotch tape test evaluations. During potential cycling, the film color of P(3HT-co-3TPP)-silica hybrid materials and P3HT coated on ITO electrode changed from orange yellow (i.e., reduced form) to dark blue (i.e., oxidized form) as the redox reactions proceeded. Effects of the material composition of P3HT along with hybrid materials on the electrochemistry, spectroelectrochemistry, thermal stability, and electrical conductivity were also studied.     

Comparatively electrochemical studies at different operational temperatures for the effect of layered silicate and spherical silica on the anticorrosion efficiency of PANI nanocomposite coatings

In this paper, a series of PANI nanocomposites have been successfully prepared by in situ oxidative polymerization. The as-prepared PANI nanocomposites were subsequently characterized by WAXRD patterns and TEM. It should be noted that the nanocomposite coating containing 3 wt-% of organophilic clay loading was found to exhibit an observable enhanced corrosion protection on cold-rolled steel (CRS) electrode at higher operational temperature of 50 degrees C, which was even better than that of uncoated and electrode-coated with PANI or PANI nanocomposites with 3 wt-% of amino-modified silica nanoparticles alone at room temperature of 30 degrees C based on the electrochemical parameter evaluations (e.g., E(corr), R(p), I(corr), R(corr) and impedance). The vapor permeability property at three different operational temperatures of PANI and PANI nanocomposite membranes were investigated by vapor permeability analyzer (VPA). Effect of material composition on the molecular weight, optical properties and surface hydrophobicity of neat PANI and PANI nanocomposite, in the form of membrane and solution, were studied by gel permeation chromatography (GPC), ultraviolet-visible absorption spectra and contact-angle measurements, respectively. Finally, electrical conductivity at three different operational temperatures of PANI and PANI nanocomposite powder-pressed pellets was also investigated through the measurements of standard four-point-probe technique.     

Energy minimization using multiple supply voltages

We present a dynamic programming technique for solving the multiple supply voltage scheduling problem in both nonpipelined and functionally pipelined data-paths. The scheduling problem refers to the assignment of a supply voltage level (selected from a fixed and known number of voltage levels) to each operation in a data flow graph so as to minimize the average energy consumption for given computation time or throughput constraints or both. The energy model is accurate and accounts for the input pattern dependencies, re-convergent fanout induced dependencies, and the energy cost of level shifters. Experimental results show that using three supply voltage levels on a number of standard benchmarks, an average energy saving of 40.19% (with a computation time constraint of 1.5 times the critical path delay) can be obtained compared to using a single supply voltage level     

Enhancement of corrosion protection effect of poly(o-ethoxyaniline) via the formation of poly(o-ethoxyaniline)-clay nanocomposite materials

A series of polymer-clay nanocomposite (PCN) materials that consisted of emeraldine base of poly(o-ethoxyaniline) (PEA) and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic MMT clay platelets in organic PEA matrix via in situ oxidative polymerization. Organic o-ethoxyaniline monomers were first intercalated into the interlayer regions of organophilic clay hosts and were followed by a one-step oxidative polymerization. The as-synthesized PCN materials were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM).PCN materials at low clay loading up to 3 wt% in the form of coating (e.g. 0.5 wt%) on cold-rolled steel (CRS) were found to exhibit much superior corrosion inhibition effect as compared to those of the bulk PEA by performing a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5 wt% aqueous NaCl electrolyte. Furthermore, it was found that a further increase of clay loading up to 3 wt% results in a slightly enhanced molecular barrier property of PCN materials. The molecular weights of PEA extracted from PCN materials and bulk PEA were determined by gel permeation chromatography (GPC) analysis with NMP as eluant. Effects of the material composition on the molecular barrier, thermal stability, electrical conductivity and optical properties of PEA along with a series of PCN materials, in the form of free-standing film, fine powder and solution, were also studied by molecular permeability measurements (GPA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), four-point probe technique and UV-vis spectra.     

Seamless Streaming Media for Heterogeneous Mobile Networks

As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access network, and thus the feasibility of the proposed architecture is demonstrated.

Tailoring of broadband dispersion-compensating photonic crystal fibre

This paper presents a broadband dispersion-compensating photonic crystal fibre (B-DCPCF) with a high compensation ratio of 30:1. We theoretically tailored the negative dispersion in a photonic crystal fibre (PCF) to nullify the positive dispersion in the transmission fibre over a bandwidth range of as wide as possible. The numeric results indicate that the effective dispersion within ±0.64 ps/nm/km over a bandwidth range of 226 nm (from 1338 to 1564 nm), cover the E + S + C wavelength bands. Finally, the confinement loss and the modal properties were examined to verify that the proposed B-DCPCF with extremely low confinement loss and should be operated in single mode throughout the operating band.     

Performance characteristic studies of glucose biosensors modified by (3-mercaptopropyl)trimethoxysilane sol–gel and non-conducting polyaniline

The materials (3-mercaptopropyl)trimethoxysilane (MPTMS) sol–gel and non-conducting polyaniline (PAn) were prepared for coating on two different amperometric biosensors fabricated by the immobilization of glucose oxidase (GOx) in conducting polyaniline (PA) as permselective membranes. A few performance characteristics of the MPTMS and the PAn-modified glucose sensors are comparable. In detecting 1 mM glucose, the biosensors’ response times were 11 and 12 s, respectively, and results from the repeating measurements (N = 10) showed that R.S.D. = 2.09 and 1.70%, respectively. The detection linearity of the two biosensors was up to 12.5 mM with R = 0.9989 and 0.9969. When they were used to detect 0.5 mM of ascorbic acid (AA), uric acid (UA), and acetaminophen at an anodic potential of 0.4 V, current signals were either insignificant or invisible. The PAn-coated glucose sensor exhibited superior sensitivity at 18.91 μA/(mM cm²), and a maximum current density of 3.70 mA/cm². GOx in the MPTMS-modified biosensor presented a stronger affinity to glucose with K_m = 48.87. More importantly, the stability of this biosensor is superior to that of the PAn-modified biosensor and has lasted for almost 5 months.     

Comparative studies on the corrosion protection effect of DBSA-doped polyaniline prepared from in situ emulsion polymerization in the presence of hydrophilic Na-MMT and organophilic organo-MMT clay platelets

A series of polyaniline (PANI)/Na⁺-montmorillonite (MMT) clay and PANI/organo-MMT nanocomposite materials have been successfully prepared by in situ emulsion polymerization in the presence of inorganic nanolayers of hydrophilic Na⁺-MMT clay or organophilic organo-MMT clay with DBSA and KPS as surfactant and initiator, respectively. The as-synthesized Na⁺-PCN and organo-PCN materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).Na⁺-PCN materials in the form of coatings with low loading of Na⁺-MMT clay (e.g., 3 wt.%, CLAN3) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of organo-PCN materials with same clay loading based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5 wt.% aqueous NaCl electrolyte. The molecular weights of PANI extracted from PCN materials and neat PANI were determined by gel permeation chromatography (GPC) with NMP as eluant. Effects of material composition on the gas permeability, optical properties and electrical conductivity of neat PANI and a series of PCN materials, in the form of free-standing film, solution and powder-pressed pellet, were also studied by gas permeability analyzer (GPA), ultraviolet-vis spectra and four-point probe technique, respectively.