Comparison of different current collecting modes of anode supported micro-tubular SOFC through mathematical modeling

A two-dimensional model comprising fuel channel, anode, cathode and electrolyte layers for anode-supported micro-tubular solid oxide fuel cell (SOFC), in which momentum, mass and charge transport are considered, has been developed. By using the model, tubular cells operating under three different modes of current collection, including inlet current collector (IC), outlet current collector (OC) and both inlet and outlet collector (BC), are proposed and simulated. The transport phenomena inside the cell, including gas flow behavior, species concentration, overpotential, current density and current path, are analyzed and discussed. The results depict that the model can well simulate the diagonal current path in the anode. The current collecting efficiency as a function of tube length is obtained. Among the three proposed modes, the BC mode is the most effective mode for a micro-tubular SOFC, and the IC mode generates the largest current density variation at z-direction.     

Start-up of autotrophic nitrogen removal reactors via sequential biocatalyst addition

A procedure for start-up of oxygen-limited autotrophic nitrification-denitrification (OLAND) in a lab-scale rotating biological contactor (RBC) is presented. In this one-step process, NH4+ is directly converted to N2 without the need for an organic carbon source. The approach is based on a sequential addition of two types of easily available biocatalyst to the reactor during start-up: aerobic nitrifying and anaerobic, granular methanogenic sludge. The first is added as a source of aerobic ammonia-oxidizing bacteria (AAOB), the second as a possible source of planctomycetes including anaerobic ammonia-oxidizing bacteria (AnAOB). The initial nitrifying biofilm serves as a matrix for anaerobic cell incorporation. By subsequently imposing oxygen limitation, one can create an optimal environment for autotrophic N removal. In this way, N removal of about 250 mg of N L(-1) d(-1) was achieved after 100 d treating a synthetic NH4+-rich wastewater. By gradually imposing higher loads on the reactor, the N elimination could be increased to about 1.8 g of N L(-1) d(-1) at 250 d. The resulting microbial community was compared with that of the inocula using general bacterial and AAOB- and planctomycete-specific PCR primers. Subsequently, the RBC reactor was shown to treat a sludge digestor effluent under suboptimal and strongly varying conditions. The RBC biocatalyst was also submitted to complete absence of oxygen in a fixed-film bioreactor (FFBR) and proved able to remove NH4+ with NO2- as electron acceptor (maximal 434 mg of NH4+-N (g of VSS)(-1) d(-1) on day 136). DGGE and real-time PCR analysis demonstrated that the RBC biofilm was dominated by members of the genus Nitrosomonas and close relatives of Kuenenia stuttgartiensis, a known AnAOB. The latter was enriched during FFBR operation, but AAOB were still present and the ratio planctomycetes/AAOB rRNA gene copies was about 4.3 after 136 d of reactor operation. Whether this relates to an active role of AAOB in the anoxic N removal process remains to be solved.     

Use of Furandicarboxylic Acid and Its Decyl Ester as Additives in the Fischer’s Glycosylation of Decanol by d-Glucose: Physicochemical Properties of the Surfactant Compositions Obtained

2,5-Furandicarboxylic acid is a promising bio-based platform chemical that may serve as a ‘green’ substitute for terephthalate in polyesters. In the present work, straightforward glycosylation of decanol with unprotected and non-activated d-glucose was performed under reduced quantities of sulfuric acid as catalyst (down to 0.9 mol%) in the presence of 2,5-furandicarboxylic acid or its n-decyl ester as additive. Yield of decyl monoglucosides was highly improved by the use of the additives. Moreover, the presence of additive also limited the colouration of the reaction. The physical and chemical properties of the surfactant composition produced were studied and compared to reference compositions. The ultimate biodegradability of furan-2,5-dicarboxylic acid (FDCA) and its n-decyl ester formed or produced in the bulk reaction medium was also studied in order to assess its potential use in surfactant industry.     

Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask

Background

Exposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask.

Methods

In an open-label cross-over randomised controlled trial, 15 healthy volunteers (median age 28 years) walked on a predefined city centre route in Beijing in the presence and absence of a highly efficient facemask. Personal exposure to ambient air pollution and exercise was assessed continuously using portable real-time monitors and global positional system tracking respectively. Cardiovascular effects were assessed by continuous 12-lead electrocardiographic and ambulatory blood pressure monitoring.

Results

Ambient exposure (PM_2.5 86 ± 61 vs 140 ± 113 μg/m³; particle number 2.4 ± 0.4 vs 2.3 ± 0.4 × 10⁴ particles/cm³), temperature (29 ± 1 vs 28 ± 3°C) and relative humidity (63 ± 10 vs 64 ± 19%) were similar (P > 0.05 for all) on both study days. During the 2-hour city walk, systolic blood pressure was lower (114 ± 10 vs 121 ± 11 mmHg, P < 0.01) when subjects wore a facemask, although heart rate was similar (91 ± 11 vs 88 ± 11/min; P > 0.05). Over the 24-hour period heart rate variability increased (SDNN 65.6 ± 11.5 vs 61.2 ± 11.4 ms, P < 0.05; LF-power 919 ± 352 vs 816 ± 340 ms², P < 0.05) when subjects wore the facemask.

Conclusion

Wearing a facemask appears to abrogate the adverse effects of air pollution on blood pressure and heart rate variability. This simple intervention has the potential to protect susceptible individuals and prevent cardiovascular events in cities with high concentrations of ambient air pollution.