There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Microbial fuel cell (MFC) research is a rapidly evolving field that lacks established terminology and methods for the analysis of system performance. This makes it difficult for researchers to compare devices on an equivalent basis. The construction and analysis of MFCs requires knowledge of different scientific and engineering fields, ranging from microbiology and electrochemistry to materials and environmental engineering. Describing MFC systems therefore involves an understanding of these different scientific and engineering principles. In this paper, we provide a review of the different materials and methods used to construct MFCs, techniques used to analyze system performance, and recommendations on what information to include in MFC studies and the most useful ways to present results.

Microbial Fuel Cells: Methodology and Technology†

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(08)00159-5.pdf

Towards practical implementation of bioelectrochemical wastewater treatment.

High-rate electron transfer toward an anode in microbial fuel cells(MFCs) has thus far not been described for bacteria-producing soluble redox mediators. To study the mechanism of electron transfer, we used a MFC isolate, Pseudomonas aeruginosa strain KRP1. Bacterial electron transfer toward the MFC anode was enabled through pyocyanin and phenazine-l-carboxamide. The presence of the anode stimulated pyocyanin production. Mutant strains, deficient in the synthesis of pyocyanin and phenazine-1-carboxamide, were unable to achieve substantial electron transfer and reached only 5% of the wild type's power output. Upon pyocyanin addition, the power output was restored to 50%. Pyocyanin was not only used by P. aeruginosa to improve electron transfer but as well enhanced electron transfer by other bacterial species. The finding that one bacterium can produce electron shuttles, which can be used also by other bacteria, to enhance electron-transfer rate and growth, has not been shown before. These findings have considerable implications with respect to the power output attainable in MFCs.

Microbial phenazine production enhances electron transfer in biofuel cells

Connecting several microbial fuel cell (MFC) units in series or parallel can increase voltage and current; the effect on the microbial electricity generation was as yet unknown Six individual continuous MFC units in a stacked configuration produced a maximum hourly averaged power output of 258 W m(-3) using a hexacyanoferrate cathode The connection of the 6 MFC units in series and parallel enabled an increase of the voltages (202 V at 228 W m(-3)) and the currents (255 mA at 248 W m(-3)), while retaining high power outputs During the connection in series, the individual MFC voltages diverged due to microbial limitations at increasing currents With time, the initial microbial community decreased in diversity and Gram-positive species became dominant The shift of the microbial community accompanied a tripling of the short time power output of the individual MFCs from 73 W m(-3) to 275 W m(-3), a decrease of the mass transfer limitations and a lowering of the MFC internal resistance from 65 +/- 10 to 39 +/- 05 omega This study demonstrates a clear relation between the electrochemical performance and the microbial composition of MFCs and further substantiates the potential to generate useful energy by means of MFCs

/pdf/continuous-electricity-generation-at-high-voltages-and-11np0kz1p3.pdf

Continuous Electricity Generation at High Voltages and Currents Using Stacked Microbial Fuel Cells

A microbial fuel cell containing a mixed bacterial culture utilizing glucose as carbon source was enriched to investigate power output in relation to glucose dosage. Electron recovery in terms of electricity up to 89% occurred for glucose feeding rates in the range 0.5–3 g l−1 d−1, at powers up to 3.6 W m−2 of electrode surface, a five fold higher power output than reported thus far. This research indicates that microbial electricity generation offers perspectives for optimization.

A microbial fuel cell capable of converting glucose to electricity at high rate and efficiency.

Microbial fuel cells (MFCs) that remove carbon as well as nitrogen compounds out of wastewater are of special interest for practice. We developed a MFC in which microorganisms in the cathode performed a complete denitrification by using electrons supplied by microorganisms oxidizing acetate in the anode. The MFC with a cation exchange membrane was designed as a tubular reactor with an internal cathode and was able to remove up to 0.146 kg NO3--N m(-3) net cathodic compartment (NCC) d(-1) (0.080 kg NO3--N m(-3) total cathodic compartment d(-1) (TCC)) at a current of 58 A m(-3) NCC (32 A m(-3) TCC) and a cell voltage of 0.075 V. The highest power output in the denitrification system was 8 W m(-3) NCC (4 W m(-3) TCC) with a cell voltage of 0.214 V and a current of 35 A m(-3) NCC. The denitrification rate and the power production was limited by the cathodic microorganisms, which only denitrified significantly at a cathodic electrode potential below 0 V versus standard hydrogen electrode (SHE). This is, to our knowledge, the first study in which a MFC has both a biological anode and cathode performing simultaneous removal of an organic substrate, power production, and complete denitrification without relying on H-2-formation or external added power.

Korneel Rabaey

Papers

Towards practical implementation of bioelectrochemical wastewater treatment.

Microbial phenazine production enhances electron transfer in biofuel cells

Continuous Electricity Generation at High Voltages and Currents Using Stacked Microbial Fuel Cells

A microbial fuel cell capable of converting glucose to electricity at high rate and efficiency.

Biological denitrification in microbial fuel cells.