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ABSTRACT: Given few in-depth studies available on the application of nitrogen-doped carbon powders (NDCP) to air-cathode microbial fuel cells (ACMFCs), a low-cost and durable catalyst of NDCP was prepared and used as cathodic catalyst of ACMFCs. Compared to the untreated carbon powders, the N-doped treatment significantly increased the maximum power density (MPD) of ACMFC. A two-step pretreatment of heat treatment and hydrochloric acid immersion can further obviously increase the MPD. With a reasonably large loading of catalyst, the MPD of NDCP based ACMFC was comparable to that of carbon-supported platinum (Pt/C) based ACMFC, while the cost was dramatically reduced. The pretreatment increased the key nitrogen functional groups, pyridinic-like and pyrrolic-like nitrogen. A third new key nitrogen functional group, nitrogen oxide, was discovered and the mechanism of its contribution was explained. Compared to the inherent deterioration problem of Pt/C, NDCP exhibited high stability and was superior for long-term operation of ACMFCs.
Bioresource technology 03/2012; 108:89-93. · 4.25 Impact Factor
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ABSTRACT: Microbial fuel cells often produce more electrical power with mixed cultures than with pure cultures. Here, we show that a coculture of a nonexoelectrogen (Escherichia coli) and Geobacter sulfurreducens improved system performance relative to that of a pure culture of the exoelectrogen due to the consumption of oxygen leaking into the reactor.
Applied and environmental microbiology 02/2012; 78(9):3484-7. · 3.69 Impact Factor
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ABSTRACT: A recirculation microbial desalination cell (rMDC) was designed and operated to allow recirculation of solutions between the anode and cathode chambers. This recirculation avoided pH imbalances that could inhibit bacterial metabolism. The maximum power density was 931±29mW/m(2) with a 50mM phosphate buffer solution (PBS) and 776±30mW/m(2) with 25mM PBS. These power densities were higher than those obtained without recirculation of 698±10mW/m(2) (50mM PBS) and 508±11mW/m(2) (25mM PBS). The salt solution (20g/L NaCl) was reduced in salinity by 34±1% (50mM) and 37±2% (25mM) with recirculation (rMDC), and by 39±1% (50mM) and 25±3% (25mM) without recirculation (MDC). These results show that electrolyte recirculation using an rMDC is an effective method to increase power and achieve efficient desalination by eliminating pH imbalances.
Bioresource technology 11/2011; 106:89-94. · 4.25 Impact Factor
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ABSTRACT: Pyrite is a common mineral at many mining sites. In this study, the mineral pyrite was studied as a Fenton-like reagent for environmental concerns. We selected lactate as a model target molecule to evaluate the Fenton-like catalytic efficiency of pyrite upon organic oxidation. A complete set of control experiments in both aerobic and anaerobic atmospheres unequivocally established that the pyrite in aqueous solution could spontaneously in situ generate (·)OH and H(2)O(2), serving as a Fenton-like reagent to catalyze the oxidation of lactate to pyruvate with no need for additional H(2)O(2). We called it the pyrite-only Fenton-like (PF) reagent. Monitoring concentration changes of lactate and pyruvate with the time indicated that the pyrite mediated the favorable pyruvate formation at pH 4.5, 60 °C, under air atmosphere. The PF reaction could be stimulated by visible light illumination. Under the optimum conditions, up to 50% of lactate was degraded within 10d. The results suggest that pyrite and its Fenton-like processes may be potentially practical in wastewater treatment.
Chemosphere 11/2011; 86(4):376-82. · 3.21 Impact Factor
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ABSTRACT: protein glycosylation varies with the physiological and pathological status of the cell. Consequently, analysis of protein-linked glycans has growing importance both in basic glycobiological research and as a potential tool for monitoring the physiological state in humans.
a total of 265 healthy northern Chinese men and women were grouped by age and gender. The mean age in males and females was similar.
the study is aimed to evaluate the effects of the age and gender on the human serum N-glycans profiles in the clinical diagnose of ageing and disease.
the 265 human serum N-glycan profiles were obtained by DNA sequencer-assisted fluorophore-assisted carbohydrate electrophoresis. Comparison of N-glycan profiles was carried out among the different genders and age groups and the data were analysed with the GeneMapper software.
age-related changes in the three N-glycan structures (NGA2F, NGA2FB and NA2F) were observed. Interestingly, fucosylation of N-glycans was significantly different (P < 0.0001) between men and women: more core-α-1,6-fucosylated glycans were detected in women, whereas more branching-α-1,3-fucosylated N-glycans were seen in men.
the N-glycome profile in serum is gender and age dependent. This should be taken into consideration in the development of serum glycome markers.
Age and Ageing 09/2011; 40(5):568-75. · 3.09 Impact Factor
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ABSTRACT: Because of the advantages of low cost, good electrical conductivity and high oxidation resistance, nitrogen-doped carbon (NDC) materials have a potential to replace noble metals in microbial fuel cells (MFCs) for wastewater treatment. In spite of a large volume of studies on NDC materials as catalysts for oxygen reduction reaction, the influence of sulfide on NDC materials has not yet been explicitly reported so far. In this communication, nitrogen-doped carbon powders (NDCP) were prepared by treating carbon powders in nitric acid under reflux condition. Sodium sulfide (Na(2)S) was added to the cathodic electrolyte to compare its effects on platinum (Pt) and NDCP cathodes. Cell voltages, power density and cathodic potentials were monitored without and with Na(2)S and after Na(2)S was removed. The maximum cell voltage of the MFCs with Pt cathode decreased by 10% in the presence of Na(2)S that did not change the performance of the MFC with NDCP cathode, and the maximum power density of the MFC with NDCP cathode was even 11.3% higher than that with Pt cathode (222.5 ± 8 mW m(-2) vs. 199.7 ± 4 mW m(-2)).
Biosensors & bioelectronics 08/2011; 35(1):413-5. · 5.43 Impact Factor
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ABSTRACT: The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS(2) redox system on the interconversion between several pairs of α-hydroxy acids and α-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized α-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS(2) redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world. Key Words: Iron-sulfur world-FeS/S/FeS(2) redox system-Oxidoreductase-like chemistry. Astrobiology 11, 471-476.
Astrobiology 06/2011; 11(5):471-6. · 2.15 Impact Factor
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ABSTRACT: A microbial consortium with a high cellulolytic activity was enriched to degrade raw corn stover powder (RCSP). This consortium degraded more than 51% of non-sterilized RCSP or 81% of non-sterilized filter paper within 8 days at 40°C under facultative anoxic conditions. Cellulosome-like structures were observed in scanning electron micrographs (SEM) of RCSP degradation residue. The high cellulolytic activity was maintained during 40 subcultures in a medium containing cellulosic substrate. Small ribosomal gene sequence analyses showed the consortium contains uncultured and cultured bacteria with or without cellulolytic activities. Among these bacteria, some are anaerobic others aerobic. Analyses of the culture filtrate showed a typical anoxic polysaccharide fermentation during the culturing process. Reducing sugar concentration increased at early stage followed by various fermentation products that were consumed at the late stage.
Bioresource technology 01/2011; 102(2):742-7. · 4.25 Impact Factor
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ABSTRACT: Corn stover is usually treated by an energy-intensive or expensive process to extract sugars for bioenergy production. However, it is possible to directly generate electricity from corn stover in microbial fuel cells (MFCs) through the addition of microbial consortia specifically acclimated for biomass breakdown. A mixed culture that was developed to have a high saccharification rate with corn stover was added to single-chamber, air-cathode MFCs acclimated for power production using glucose. The MFC produced a maximum power of 331 mW/m2 with the bioaugmented mixed culture and corn stover, compared to 510 mW/m2 using glucose. Denaturing gradient gel electrophoresis (DGGE) showed the communities continued to evolve on both the anode and corn stover biomass over 60 days, with several bacteria identified including Rhodopseudomonas palustris. The use of residual solids from the steam exploded corn stover produced 8% more power (406 mW/m2) than the raw corn stover. These results show that it is possible to directly generate electricity from waste corn stover in MFCs through bioaugmentation using naturally occurring bacteria.
Environmental Science and Technology 09/2009; 43(15):6088-93. · 5.23 Impact Factor
