A Novel Stackelberg-Game-Based Energy Storage Sharing Scheme Under Demand Charge

Demand response (DR) using shared energy storage systems (ESSs) is an appealing method to save electricity bills for users under demand charge and time-of-use (TOU) price. A novel Stackelberg-game-based ESS sharing scheme is proposed and analyzed in this study. In this scheme, the interactions between selfish users and an operator are characterized as a Stackelberg game. Operator holds a large-scale ESS that is shared among users in the form of energy transactions. It sells energy to users and sets the selling price first. It maximizes its profit through optimal pricing and ESS dispatching. Users purchase some energy from operator for the reduction of their demand charges after operator’s selling price is announced. This game-theoretic ESS sharing scheme is characterized and analyzed by formulating and solving a bi-level optimization model. The upper-level optimization maximizes operator’s profit and the lower-level optimization minimizes users’ costs. The bi-level model is transformed and linearized into a mixed-integer linear programming (MILP) model using the mathematical programming with equilibrium constraints (MPEC) method and model linearizing techniques. Case studies with actual data are carried out to explore the economic performances of the proposed ESS sharing scheme.      

Monoolein–Water Liquid Crystalline Gels of Gentamicin as Bioresorbable Implants for the Local Treatment of Chronic Osteomyelitis: In Vitro Characterization

To maximize the efficacy of chronic osteomyelitis antibiotherapy while reducing antibiotic systemic toxicity, as well as time and costs of hospitalizations, it has been thought that monoolein–water gels incorporating gentamicin sulfate could be used as local, bioresorbable, and sustained-release implants. For this purpose, four formulations were examined with regard to their physicochemical and in vitro drug release characteristics. Hot stage microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction showed cubic liquid crystalline and eutectic structures. The more suitable formulation consisting of 80–15–5% wt/wt monoolein–water–gentamicin sulfate progressively released the antibiotic for a period of 3 weeks without burst effect. Moreover, the content and the release profile of gentamicin sulfate were not significantly changed after storage at 2–6°C for a period of 10 months.     

Modification of porous carbon tubes with enzymes: application for biofuel cells

Enzyme biocatalyst assemblies on electrode surfaces can be used to construct efficient membrane-less biofuel cells. The present study reports on the construction of biocatalytic oxygen electrodes based on the modification of porous carbon tubes with laccase and 2,2′-azinobis-(3-ethylbenzothiazoline−6-sulfonate) (ABTS²⁻) as mediator, co-immobilized within electrochemically polymerized films. Porous carbon tubes are used as original conducting support for enzyme incorporation and for the transport of dissolved dioxygen solution via diffusive flow through the porosity. The activity of the laccase immobilized on the porous carbon support is determined. Performance of the biocathodes towards the reduction of dioxygen to water is demonstrated by chronoamperometry at +0.4 V vs. Ag/AgCl in citrate/phosphate buffer pH 3. Moreover, the current–voltage behaviour of the biocathodes show high current densities at pH 3 (a current peak equal to 280 μA cm⁻² for the biocathode based on both entrapped laccase and mediator) and a low oxygen reduction overvoltage compared to platinum electrode.     

Mercury in fruiting bodies of dark honey fungus (Armillaria solidipes) and beneath substratum soils collected from spatially distant areas

BACKGROUND: This paper reports data on bioconcentration potential and baseline mercury concentrations of fruiting bodies of dark honey fungus (Armillaria solidipes) Peck and soil substrate layer (0–10 cm) from 12 spatially distant sites across Poland. Mercury content of caps, stipes and soil samples were determined using validated analytical procedure including cold‐vapor atomic absorption spectroscopy after thermal decomposition of the sample matrix and further amalgamation and desorption of mercury from gold wool. RESULTS: Mean mercury concentrations ranged from 20 ± 8 to 300 ± 70 ng g^?1 dry weight (dw) in caps, from 20 ± 6 to 160 ± 40 ng g^?1 dw in stipes, and in underlying soil were from 20 ± 2 to 100 ± 130 ng g^?1 dw. The results showed that stipes mercury concentrations were 1.1‐ to 1.7‐fold lower than those of caps. All caps and the majority of stipes were characterized by bioconcentration factor values > 1, indicating that dark honey fungus can be characterized as a moderate mercury accumulator. CONCLUSION: Occasional or relatively frequent eating of meals including caps of dark honey fungus is considered safe in view of the low total mercury content, and the mercury intake rates are below the current reference dose and provisionally tolerable weekly intake limits for this hazardous metal. © 2012 Society of Chemical Industry     

Binding Mode and Structure–Activity Relationships around Direct Inhibitors of the Nrf2–Keap1 Complex

An X‐ray crystal structure of Kelch‐like ECH‐associated protein (Keap1) co‐crystallised with (1S,2R)‐2‐[(1S)‐1‐[(1,3‐dioxo‐2,3‐dihydro‐1H‐isoindol‐2‐yl)methyl]‐1,2,3,4‐tetrahydroisoquinolin‐2‐carbonyl]cyclohexane‐1‐carboxylic acid (compound (S,R,S)‐ 1 a ) was obtained. This X‐ray crystal structure provides breakthrough experimental evidence for the true binding mode of the hit compound (S,R,S)‐ 1 a , as the ligand orientation was found to differ from that of the initial docking model, which was available at the start of the project. Crystallographic elucidation of this binding mode helped to focus and drive the drug design process more effectively and efficiently.     

Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites

A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.     

Long-term activity of covalent grafted biocatalysts during intermittent use of a glucose/O2 biofuel cell

The operational stability of enzymes in a concentric glucose/O₂ biofuel cell has been significantly improved with the synthesis of grafted enzyme electrodes compared to entrapped enzyme electrodes. The concentric device combined glucose electro-oxidation by glucose oxidase at the anode and oxygen electro-reduction by bilirubin oxidase at the cathode. The entrapped enzyme electrodes were prepared from physical immobilization of the enzymes by a polypyrrole polymer onto the electrode surface. The grafted enzyme electrodes were synthesized by grafting the enzymes via alkyl spacer arms to a poly(aminopropylpyrrole) film onto the electrode surface. From spectrophotometric and electrochemical analyses, it was demonstrated that the spacer arms increased the operational stability and enzyme mobility that favoured electron transfer from their active sites to the electrode.The maximum power output of the assembled biofuel cell was 20 μW cm⁻², at 0.20 V with 10 mM glucose in phosphate buffer pH 7.4. The grafted enzyme electrodes presented an unprecedented operational stability as the maximum of power density of the BFC remains constant after intermittent use over a 45-day period. This was a remarkable improvement compared to electrodes with entrapped enzymes, which lost 74% of their initial power density after intermittent use over a 17-day period.     

Flow Pattern and Heat Transfer in a Cylindrical Annulus Under 1 g and Low-g Conditions: Experiments

We investigate the thermal convection in an annular cavity, with differentially heated inner and outer cylinders, under the influence of a dielectrophoretic (DEP) force. Applying a temperature gradient to a liquid creates buoyancy driven thermal convection. When additionally a radially acting DEP-force is applied by means of an alternating electric field, the pattern of this convective flow changes which also leads to a change in the heat transfer. Depending on the parameters, e.g. an axisymmetric structure with toroidal vortices appears. Another possible structure are columnar vortices, which extend through the annulus. To isolate the effect of the DEP-force, this experiment is not only conducted in the laboratory, but also in microgravity conditions during parabolic flights. By using DEP-induced convective flows in microgravity a comparable heat transfer as with buoyancy convection under Earth’s condition can be obtained. A better understanding of the heat transport mechanisms inside a dielectric liquid confined between two concentric cylinders can deliver solutions for the improvement of the heat transport in many technical applications.     

Inventory of water management practices in Harare, Zimbabwe

Lake Chivero, in Zimbabwe, is the major water supply source for the greater Harare area. This paper looks at the sustainability of current practices of the urban water cycle in relation to water quantity and quality management in the Chivero catchment. Data on population, water supply, water and wastewater treatment and river flows were obtained from urban councils and government departments. The data were used to assess water consumption, wastewater generation, treatment and disposal practices, river flow trends, raw water abstractions and water demand patterns. The results showed that the current situation is not sustainable as water quantity in the catchment will soon be a problem at current levels of consumption while water quality is already a problem, especially with regard to nutrient levels. Water and nutrient management strategies, which include water use efficiency, treatment and water recycling and nutrient reuse in controlled urban agriculture, are recommended as matters of urgency.