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To fabricate effective and stable OER electrode in water electrolysis, self-doped TiO2 nanotube arrays which has a higher electrical conductivity than pristine TiO2 nanotube arrays was used as the support for loading IrO2. The self-doped TNTA was fabricated by a simple electrochemical reduction of TNTA in neutral electrolyte solution, and then IrO2 nano particles were deposited by pulse electro-deposition method. The cyclic voltammetric behavior, electrical conductivity and micro structure of self-doped TNTA prepared at different reduction potential were characterized to obtain an optimal performance, and self-doped TNTA prepared under −1.9 V (vs. Ag/AgCl) shows the best electrochemical performance. After depositing IrO2, the OER activity and stability of new electrodes were also determined. Due to the enhanced electrical conductivity of support, the mass activity of IrO2/self-doped TNTA are 50 times higher than IrO2/TNTA. The OER stability of new electrode was evaluated under constant current of 5 mA/cm2, IrO2/TNTA and IrO2/Ti were also tested for comparison. A higher stability of IrO2/self-doped TNTA electrode is observed than the other two electrodes, and XPS studies indicate a lower oxidation state of Ir in IrO2/self-doped TNTA, this shows a possible interactions between IrO2 and the new support.

This work offers a typical understanding of the factors that govern the nanostructures of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine) (P4VP-b-PS-b-P4VP) block copolymers (BCs) in dioxane/water, in which water is a selective solvent for the P4VP block. It is achieved through an investigation of the amphiphilic triblock copolymer micelles by variation of three different factors, including water content (above CWC but under the immobile concentration), temperature (ranging from 20 °C to 80 °C), and copolymer composition (low and high PS block length). Transition of bead-like micelles to vesicles is observed with the increase of water content due to the increase of interfacial energy between the copolymer and the solvent. Effect of temperature superposed on that of water content results in various morphologies, such as beads, fibers, rods, capsules, toroids, lamellae, and vesicles. The interfacial tension between the BC and the solvent increases with the increase of water content but decreases with the increase of temperature, indicating that the micellar morphologies are resulted from the competitive interplay between the temperature and the water content and always change in a direction that decreases the interfacial energy. Based on the micellar structures obtained in this work and the effects of temperature superposed on water concentration, a diagram of phase evolution of different micellar morphologies is illustrated here, covering the temperature range from 20 °C to 80 °C and the water content changing from 20 vol% to 35 vol%. For the investigation of BC composition, morphological transition of vesicle-to-fiber, for high PS length, is observed as compared with bead-to-capsule for low PS length, as the temperature changes from 20 °C to 80 °C. Our research complements the protocols to control over the morphologies and the phase diagram describing P4VP-b-PS-b-P4VP micellar nanostructures in aqueous solution.

A series of Cu-X/?-Al2O3 (X = Fe, Co, Ni) catalysts were synthesized by a rapid intermittent microwave irradiation method for hydrogen generation from dimethyl ether steam reforming. Different parameters, such as the promoters of X (X = Fe, Co, Ni), microwave irradiation procedure and the ratio of metal to ?-Al2O3, were investigated. The results show that 2Cu-Fe/72?-Al2O3 has the best performance, for which the agglomeration is prevented, CuO is well dispersed and the catalytic activity is improved. Promoter iron oxide in 2Cu-Fe/9?-Al2O3 facilitates the watergas shift reaction, which lead to an increase in the conversion of CO to CO2 and hydrogen yield. Particularly, the 2Cu-Fe/72?-Al2O3 catalyst, with the best molar ratio of metal to ?-Al2O3, shows a dimethyl ether conversion of >99% and a hydrogen yield of >98% and produces the lowest CO content of 1.4%, indicating that the synergism between dimethyl ether hydrolysis and methanol reforming requires an appropriate balance between the metallic Cu-Fe and the acid ?-Al2O3. The intermittent microwave irradiation technique provides a simple but effective method of the Cu-Fe/?-Al2O3 synthesis with a good catalyst performance for the dimethyl ether steam reforming.

This work offers an effective size-controlled synthesis of platinum nanoparticle (Pt NP) arrays for electrocatalyst through self-assembled nanopatterns of block copolymers on titanium (Ti) wafers. Size, spacing and uniformity of Pt NP with loading of Pt to a minimum were investigated to be controlled and adjusted in order to improve the electrochemically active surface area (ECSA) and ECSA stability, and Pt concentration in copolymer/chloroplatinic acid (H2PtCl6) solution was verified to be one of the most important factors to control the arrays’ structure. In our case, the Pt NPs with predictable size of 5–16.5 nm could be obtained when the Pt concentration is larger than 0.05 mg ml−1, which the dominant diameter is proved to be proportional to one-third power of the Pt concentration according to the linear relation of templates’ Pt/N mass ratio versus Pt concentration, and the Pt NPs remain highly ordered arrays with predictable spacing when the Pt concentration is larger than 0.125 mg ml−1. Decrease in Pt concentration from 2 to 0.125 mg ml−1 is an effective method to improve the ECSA and durability simultaneously. The Pt NP arrays exhibit not only a remarkable initial ECSA value of 106.2 m2 g−1, but also a pseudo-zero particle aggregation possibility during 3000-cycle voltammetry, which is attributed to the high Pt NP dispersion and the ordered arrays that improve the Pt utilization and lower the possibility of aggregation.

Sorption enhanced steam reforming of acetic acid over sorbent assisted catalyst of Ni-CaO-La2O3 were investigated for high-purity H2 production. Ni-CaO-La2O3 with 8, 16 and 20 wt% Ni were developed by sol-gel combustion synthesis and were characterized by TG, TPR, BET, SEM, XRD and XPS. The catalytic activities and stability of the catalysts were tested in a fixed reactor. H2 yield and H2 concentration through Ni-CaO-La2O3 with 20 wt% Ni reaches 86.02% and 92.24% during pre-breakthrough period, respectively, which is attributed to sufficient Ni active sites on the surface and good Ni dispersion. Catalytic activities of Ni-CaO-La2O3 with 20 wt% Ni maintain stable during sorption-enhanced steam reforming reaction, but CO2 sorption capacity slightly decreases due to blockage of pores and size increase of CaO particles within nine sorption/desorption cycles.

Porous silica coated Ni/CeO 2 ZrO 2 catalysts were synthesized for steam reforming of acetic acid. The silica coated Ni/CeO 2 ZrO 2 catalyst showed a significantly enhanced activity (95% acetic acid conversion) than the Ni/CeO 2 ZrO 2 catalysts (62% acetic acid conversion) at a low temperature (550 °C). Interaction between Ni/CeO 2 ZrO 2 and silica layer was proved to be a crucial role on enhancing of catalytic activities. Further characterization (XPS, H 2 -TPR) indicates this interaction facilitates the steam reforming reaction and raises the selectivity of CO by modifying the surface Ni electronic structure. In addition, the coated catalyst also exhibited a good stability and no obvious deactivation was detected at 550 °C and 600 °C within 30 h.

This contribution focuses on the impact of shear flow on size and nanostructure of PS-based amphiphilic block copolymer (BC) micelles by varying the stirring rate and copolymer composition. The results show that the vesicles formed from diblock copolymer (di-BC) of PS-b-PAA remain with vesicular morphology, although the average size decreases, with the increase of stirring rate. However, the multi-compartment micelles (MCMs) formed from tri-block copolymer (tri-BC) of PS-b-P2VP-b-PEO are quite intricate, in which the copolymer first self-assembles into spheres, then to clusters, to large compound micelles (LCMs), and finally back to spheres, as stirring rate increases from 100 r/min to 2200 r/min. Formation mechanism studies manifest that vesicles form simultaneously as water is added to the di-BC solution, termed as directassembly, and remain with vesicular structure in the flowing process. While for the PS-b-P2VP-b-PEO copolymer, spherical micelles at initial stage can further assemble into clusters and LCMs, termed as second-assembly, due to the speeding-up-aggregation of the favorable stirring. As a result, an invert V-relationship between tri-BC micelle dimension and stirring rate is observed in contrast to the non-linear decreasing curve of di-BC vesicles. It is by investigating these various amphiphilic BCs that the understanding of shear dependence of size and morphology of micelles is improved from self-assembly to second-assembly process.

IrO2 was electro-deposited on hydrogenated TiO2 nanotube arrays (TNTA) to form IrO2/H-TNTA for oxygen evolution reaction (OER). Hydrogenation by calcining in H2 atmosphere was conducted to improve the electric conductivity, which was owing to partially reduce of Ti4+ in TNTA. It was found that hydrogenated TiO2 can facilitate the electro-deposition of IrO2, and elevate the OER activity compared to that of non-calcined and air-calcined TNTA, which would be due to the improved conductivity of H-TNTA. IrO2/H-TNTA shows a five-fold higher activity than IrO2/air-TNTA with the same loading amount. The coverage of IrO2 on the surface of hydrogenated TNTA is crucial to the stability of catalyst and with the increased loading amount of IrO2, IrO2/H-TNTA shows much higher stability.

This work contributes to a new protocol of patterning gold nanoparticles (NPs) via secondary phase-separation of micelle template of PS- b -P2VP- b -PEO block copolymer. The immiscibility between hydrophobic PS and hydrophilic P2VP and PEO leads to a bulk phase-separation in large compound micelles (LCMs) when heated at the temperature of 130 °C. The bulk-separated template then constitutes an ideal precursor for Au NPs loading by an immersion in an aqueous solution bath of chloroauric acid such that the primed P2VP domains would coordinate to the charged [AuCl 4 ] − through electrostatic interactions. With the following treatment of air plasma, pseudo-hexagonal nanopatterns are created with Au NPs on P2VP matrix.

For a typical Proton exchange membrane (PEM) water electrolysis system, reducing the amount of Ir loading at the anode in membrane electrode assembly (MEA), while maintaining the performance, is still a big challenge. Here, to improve the performance of catalyst layer for oxygen evolution reaction (OER) in an acidic medium, vertical aligned IrOx nanoarrays (IrOx NAs) were synthesized by electrodeposition with TiO2 nanotube arrays (TNTA) as template. By tuning the scan rate in the electrodeposition process, IrOx open-end nanotube arrays with tunable length ranged from 500 nm to 1400 nm and hollow nanorod arrays were obtained due to a diffusion-controlled deposition process. By constructing 3-D electrode of 1-D catalyst with enhanced ion transfer, IrOx NAs performed almost the same current density of OER with 1/20 Ir loading amount compared with commercial IrO2 nanoparticles, which could significantly reduce the cost of catalyst in PEM water electrolyser. Moreover, no apparent current decrease was observed even after 10 h’ anodic polarization under 1.55 V, which exhibit excellent OER durability.

Ordered electrode is believed to be the next generation of MEA. One-dimensional-arrays material possesses high surface area, oriented electron transfer pathway and facile mass transfer pathway, which shows great potential as electrocatalyst. For OER electrode, IrO2 is still the irreplacable choice at present status. To construct IrOx based nanotube/nanowire arrays could increase the performance of OER electrode with reduced loading amount of Iridium. Titanium oxide nanotube arrays (TNTA) is a promising candidate for the preparation of 1-D arrays electrode as its prominent stability, ordered structure and sufficient conductivity with simple modification. In order to achieve the open-end nanotube structure for the fully utilization of noble metal catalyst, controlled electrochemical deposition is applied. In our previous work, IrOx nanotube arrays performs similar current density with 1/20 loading amount of commercial IrO2 nanoparticle at the same potential. To achieve the length control of IrOx nanotube arrays, the electrodeposition of IrOx on TNTA with cyclic voltametry method was studied. By altering the scan rate, continuous IrOx nanotube arrays with different length ranged from 500 nm to 1400 nm was achieved. This phenomenon may probably due to that the deposition in the tube is diffusion controlled, while the deposition at the mouth of TNTA keeps constant due to sufficient supplement of precursor form the bulk electrolyte. In a single cycle, as the depositing goes on, the concentration gradient along the tube forms and results in uneven deposition. Different scan rate results in different duration of depositing in a single cycle. And longer duration means more uneven deposition, and leads to shorter nanotube. At present, to obtain IrOx nanotube arrays with uniform tube wall, control deposition with pulsed potential deposition method is studied. By altering the relaxation and deposition time, IrOx with uniform thickness and tunable length can be achieved. And the thickness of IrOx tube wall can be controlled, too. By achieving uniform and thinner tube wall, the utilization rate of Iridium can be further increased.

Zhida Wang,1 Pei Chu,2 Wenjin Wang2 1Comprehensive Clinical Skill Training Center, The First Hospital of Lanzhou University, Lanzhou 730030, China; 2Department of Emergency, The First Hospital of Lanzhou University, Lanzhou 730030, China Background: Rifaximin and lactulose are common effective agents for hepatic encephalopathy (HE). Whether a combination of rifaximin and lactulose improves the efficacy and mortality in patients with HE compared with lactulose alone needs to be analyzed. Methods: A systematic search was performed in electronic databases and other sources for possible studies focusing on combination therapy of rifaximin and lactulose for HE between January 2000 and February 2018. A meta-analysis was performed by the method recommended by the Cochrane Collaboration, and estimated effect size was presented as risk difference (RD), 95% CI, and the number needed to treat (NNT). Subgroup analysis, sensitivity analysis, and Trial Sequence Analysis were comprehensively performed to indicate the source of heterogeneity and risk of bias. Results: Five randomized and five observational studies involving 2,276 patients were included. Combination therapy had a significant advantage in both clinical efficacy increase (RD 0.26, 95% CI 0.19–0.32, NNT 5) and mortality decrease (RD -0.16, 95% CI -0.20–0.11, NNT 9) in overall analysis. In the pooled analysis of randomized studies, combination therapy showed similar results in clinical efficacy (RD 0.25, 95% CI 0.16–0.35, NNT 4) and mortality (RD -0.22, 95% CI -0.33–0.12, NNT 5). Compared with lactulose, hospital stay was also reduced in combination therapy, and there was no significant difference in treatment-related adverse events between the two groups. Conclusion: Combination of rifaximin and lactulose has beneficial effects on HE. Compared with lactulose alone, additional rifaximin increases clinical efficacy and decreases mortality. However, its effects on different types of HE are still uncertain. Keywords: rifaximin, lactulose, combination therapy, HE, meta-analysis

A series of Ni-based catalysts supported on Ce–Zr–O were synthesized via impregnation and applied in the reverse water gas shift reaction (RWGS). BET, XRD, TPR, SEM, TEM and XPS were employed as the characterization of catalysts. Catalytic activities of Ni/Ce–Zr–O with different Ni contents were evaluated in RWGS under atmospheric pressure and at the temperature range of 550–750 °C in a fixed-bed quartz reactor. CO2 conversion reaches 49.66% and maintains stable after 80 h of reaction over 3 wt% Ni/Ce–Zr–O. CO selectivity can reach 99.65% for the catalyst with 10 wt% Ni at 750 °C. The Ni/Ce–Zr–O catalyst provides high activity, stability and selectivity in the conversion of CO2 to CO at high temperature. Ce–Zr–O solid solution is formed by co-precipitation and Ni is able to be incorporated into the Ce–Zr–O lattice via impregnation. The Ni species on catalyst surface can be considered as the active site for RWGS.

The effect of various strain rates on the tensile behavior of a single crystal nickel-base superalloy was studied. Single crystals with (001) crystal orientation were tested at 800 and 1000 degrees C under three kinds of strain rate of 10(-3), 10(-4) and 6x10(-5) s(-1). The yield strength increased with the increase of strain rate, while the configuration of the stress-strain curves was independent of strain rate. Additionally, fracture surface was related to strain rate at two temperatures. At 800 degrees C the amount of cleavage surface was different at three strain rates, which resulted from the difference of activated slip systems. The elongation increased with the decrease of strain rate, which was influenced by the heterogeneous ductile deformation. At 1000 degrees C the difference of fracture Surface was attributed to the microvoid at higher strain Fate, while the gamma/gamma' interfaces also played an important role at lower strain rate; elongation rate was independent of strain rate. (c) 2008 Elsevier B.V. All rights reserved.

A Ni-base single crystal superalloy was transient liquid phase (TLP) bonded using a Ni-Cr-B amorphous foil at 1230 degrees C for 8 h. Stress rupture tests of the TLP joint and a matrix sample were carried out at 982 degrees C/248 MPa and 1010 degrees C/248 MPa. The microstructures and fracture surfaces were studied using scanning electron microscopy (SEM). Transmission electron microscopy (TEM) investigations were performed after creep rupture testing to examine the deformation substructures. The results show that the stress rupture ductility of TLP joints is significantly decreased compared to the matrix sample. This reduction of the ductility of TLP joints can be attributed to solid solution strengthening by boron atoms, subgrain boundaries formed in the bonding zone and the concentration of creep cavities formed during the last stage of the stress rupture test. (c) 2006 Elsevier Inc. All rights reserved.

The shape of bridge deck sections used for long-span suspension bridges has evolved through the years, from the compact box deck girders, to twin box and multi-box decks sections, which proved to have better aerodynamic behaviour, and to bring economic advantages on the construction material usage side. This thesis presents a study of a new type of multi-box bridge deck for the Megane Bridge, consisting of two side decks for traffic lanes, and two middle decks for railway traffic, connected using stabilizing beams. Aerodynamic static force coefficient measurements were performed on a section model with a scale of 1:80, for Reynolds numbers up to 5.1 × 105 under angles of attack from -10° to 10°. Also there-dimensional CFD simulations were performed by employing a Large Eddy Simulation (LES) algorithm with a standard Smagorinsky subgrid-scale model, for Re = 9.3 × 107 and angles of attack 𝛼= -4°, -2°, 0°, 2° and 4°. The experimental and numerical results were compared with respect to accuracy, sensitivity, and practical suitability. Furthermore, the aerodynamic character for each individual decks including static coefficients, wind flow pattern and pressure distribution were studied through CFD simulation. ILS (Iterative Least Squares) method was applied to extract the flutter derivatives of Megane section model based on the results obtained from free vibration tests for evaluating the flutter stability. A comparison of the flutter derivatives was carried out between bridges with different deck configurations and the results are included in this thesis.