Development of a disposable sensor for electrocatalytic detection of guanine and ss-DNA using a modified sol-gel screen-printed carbon electrode

The electrocatalytic oxidation of guanine and DNA is demonstrated on a sol-gel coated carbon screen printed electrode modified with {MeReO(edt)}₂ using cyclic and differential pulse voltammetric techniques. An oxidation peak at 370 mV was found, but no corresponding reduction peaks could be detected in the negative scan, which indicates that the oxidation of guanine is completely irreversible process. The oxidation peak potentials are shifted to more negative values with increasing pH. The utility of applying the sensor for determination of guanine and ss-DNA were investigated. The linear ranges were 0.19-10.8 and 0.45-7.8 μg ml⁻¹ for guanine and DNA, respectively. Detection limits of 0.1 and 0.32 μg ml⁻¹ were obtained for guanine and ss-DNA, respectively.     

Ultra‐selective epoxidation of styrene on pure Cu{111} and the effects of Cs promotion

Styrene undergoes efficient epoxidation to styrene epoxide on the Cu{111} surface. At the optimum condition (Θ_o = 0.03 ML) ∼20% of the styrene is converted to the epoxide with almost 100% selectivity. Comparison with Ag{111} shows that the epoxidation activity and selectivity of Cu greatly exceed those of Ag. Incipient oxidation of the Cu{111} surface does not suppress the adsorption of styrene, but the oxidised metal is catalytically inert. Submonolayer amounts of Cs enhance styrene uptake and increase conversion to the epoxide without adversely affecting epoxidation selectivity. This effect is due to inhibition of Cu oxidation by Cs. Our findings are discussed in the light of current understanding of Ag‐catalysed alkene epoxidation. This revised version was published online in July 2006 with corrections to the Cover Date.     

3-N-丙酰基-1，3，4-噁唑啉类化合物的合成

4-甲氧基苯甲酰肼（1）与芳醛反应得到相应的酰腙（2a～2j），2a～2j分别与丙酸酐脱水环化成了3-N-丙酰基-1，3，4-嗯唑啉类化合物（3a～3j），通过元素分析、IR、1^HNMR和MS对化合物3a～3j的结构进行了表征。     

Refueling-station costs for metal hydride storage tanks on board hydrogen fuel cell vehicles

Refueling costs account for much of the fuel cost for light-duty hydrogen fuel-cell electric vehicles. We estimate cost savings for hydrogen dispensing if metal hydride (MH) storage tanks are used on board instead of 700-bar tanks. We consider a low-temperature, low-enthalpy scenario and a high-temperature, high-enthalpy scenario to bracket the design space. The refueling costs are insensitive to most uncertainties. Uncertainties associated with the cooling duty, coolant pump pressure, heat exchanger (HX) fan, and HX operating time have little effect on cost. The largest sensitivities are to tank pressure and station labor. The cost of a full-service attendant, if the refueling interconnect were to prevent self-service, is the single largest cost uncertainty. MH scenarios achieve $0.71–$0.75/kg-H₂ savings by reducing compressor costs without incurring the cryogenics costs associated with cold-storage alternatives. Practical refueling station considerations are likely to affect the choice of the MH and tank design.     

Transition metal/carbon nanoparticle composite catalysts as platinum substitutes for bioelectrochemical hydrogen production using microbial electrolysis cells

Various metal nanoparticle catalysts supported on Vulcan XC-72 and carbon-nanomaterial-based catalysts were fabricated and compared and assessed as substitutes of platinum in microbial electrolysis cells (MECs). The metal-nanoparticle-loaded cathodes exhibited relatively better hydrogen production and electrochemical properties than cathodes coated with carbon nanoparticles (CNPs) and carbon nanotubes (CNTs) did. Catalysts containing Pt (alone or mixed with other metals) most effectively produced hydrogen in terms of overall conversion efficiency, followed by Ni alone or combined with other metals in the order: Pt/C (80.6%) > PtNi/C (76.8%) > PtCu/C (72.6%) > Ni/C (73.0%) > Cu/C (65.8%) > CNPs (47.0%) > CNTs (38.9%) > plain carbon felt (38.7%). Further, in terms of long-term catalytic stability, Ni-based catalysts degraded to a lesser extent over time than did the Cu/C catalyst (which showed the maximum degradation). Overall, the hydrogen generation efficiency, catalyst stability, and current density of the Ni-based catalysts were almost comparable to those of Pt catalysts. Thus, Ni is an effective and inexpensive alternative to Pt catalysts for hydrogen production by MECs.     

Investigation of Ni-coated-steel-meshes as alternative anode contact material to nickel in an SOFC stack

Solid oxide fuel cell is a promising technology to convert renewable energy sources to electricity electrochemically at high efficiencies, thus an important applied research topic worldwide. The in-house developed so-called F-stack-design aims at stationary applications and can achieve a very long lifetime. However, since production costs should be reduced, one research focus lies on finding suitable less expensive materials. Therefore, alternatives for the benchmark Ni-mesh as anode contacting element in the stack were studied. Several types of Ni-coated-steels were tested in a stack. After 3000 h of operation the different anode contact materials are compared with the Ni-mesh in terms of microstructure as well as chemical composition. A discussion of the results is given.     

MOFs in photoelectrochemical water splitting: New horizons and challenges

Growing energy consumption with the augmentation in universal population to more than nine billion by 2050 and exhausting fossil fuel reserves necessitates a harsh revolution from non-renewable energy reservoirs to renewable energy reservoirs with zero carbon emission. In the present scenario, solar energy prompted photoelectrochemical (PEC) water splitting or “Artificial Photosynthesis” via light gripping semiconductor material, originates out as the most promising methodology in accomplishing the global energy crisis. Recent studies have amply demonstrated the potential of metal-organic frameworks (MOF) towards PEC applications. They are porous crystalline coordination polymers assembled through an appropriate choice of metal ions and multidentate organic ligands. Owing to their structural regularity and synthetic tunability, MOFs integration with PEC is considered in terms of enhancing and broadening light absorption, providing active sites and directing charge transfer dynamics. Here, we have explored MOFs role in PEC and classified them into different categories such as photosensitizers, co-catalysts, counter electrode, template and also for imparting additional stability to the electrode system. MOFs mediated PEC water splitting is promising but is still rare and in its infancy. Therefore, it is pertinent and timely to take stock of the advancements made and develop insight on the use of MOFs, as an emerging solution for the problems encountered in PEC. This review covers the basics of MOF & mainly describes various case studies done during last 10 years and providing adequate impetus to researchers for critically assessing the recent advances and challenges that are faced by scientists and researchers at large.     

Semi-analytical modeling of productivity analysis for five-spot well pattern scheme in methane hydrocarbon reservoirs

Five-spot well pattern (FSWP) scheme has shown appealing potentialities to enhance the recovery of coal-bed methane (CBM) from methane hydrocarbon reservoirs (MHR). In this paper, a new framework aimed at systematically investigating productivity performance of FSWP scheme with inter-well pressure interference (IWPI) is presented. First, mathematical models which are used to characterize the fluid flow within MHR and hydraulic fractures (HFs) are separately derived. Second, Laplace transformation and Stehfest numerical algorithm are utilized to couple those two flow systems and obtain the pressure-transient solutions of FSWP scheme. Finally, pressure characteristics are discerned and sensitivity analysis of key parameters is implemented as well. This semi-analytical approach outperforms numerical simulation from the point of computational efficiency. Several common flow regimes, e.g., linear and bi-linear flow regimes, are essentially deformed induced by IWPI. Several significant parameters, including gas rate, fracture half-length, and well spacing on the occurrence of IWPI are systematically analyzed. This work gains some new knowledge about the productivity performance of FSWP scheme with the existence of IWPI when extracting CBM from methane hydrate reservoirs (MHR), which provides energy engineers considerable instructions on optimizing the development of methane hydrate reservoirs.     

Supercritical water gasification mechanism of polymer-containing oily sludge

In the offshore petroleum industry, polymer-containing oily sludge (PCOS) hinders oil extraction and causes tremendous hazards to the marine ecological environment. In this paper, an effective pretreatment method is proposed to break the adhesive structure of PCOS, and the experiments of supercritical water gasification are carried out under the influencing factors including residence time (5–30 min) and temperature (400–750 °C) in batch reactors. The increase of time and temperature all show great promoting effects on gas production. Polycyclic aromatic hydrocarbons, including naphthalene and phenanthrene, are considered as the main obstacles for a complete gasification. Carbon gasification efficiency (CE) reaches maximum of 95.82% at 750 °C, 23 MPa for 30 min, while naphthalene makes up 70% of the organic compounds in residual liquid products. The highest hydrogen yield of 19.79 (mol H₂/kg of PCOS) is observed in 750 °C for 25 min. A simplified reaction pathway is presented to describe the gaseous products (H₂, CO, CO₂, CH₄). Two intermediates are defined for describing the reaction process bases on the exhaustive study on organic matters in residual liquid products. The results show that the calculated data and the experimental data have a high degree of fit and tar formation reaction is finished within 10 min.     

The economic feasibility study of a 100-MW Power-to-Gas plant

Power-to-Gas (PtG) is a grid-scale energy storage technology by which electricity is converted into gas fuel as an energy carrier. PtG utilizes surplus renewable electricity to generate hydrogen from Solid-Oxide-Cell, and the hydrogen is then combined with CO₂ in the Sabatier process to produce the methane. The transportation of methane is mature and energy-efficient within the existing natural gas pipeline or town gas network. Additionally, it is ideal to make use of the reverse function of SOC, the Solid-Oxide-Fuel-Cell, to generate electricity when the grid is weak in power. This study estimated the cost of building a hypothetical 100-MW PtG power plant with energy storage and power generation capabilities. The emphasis is on the effects of SOC cost, fuel cost and capacity factor to the Levelized Cost of Energy of the PtG plant. The net present value of the plant is analyzed to estimate the lowest affordable contract price to secure a positive present value. Besides, the plant payback period and CO₂ emission are estimated.