微生物燃料电池阳极产电茵的选育

产电菌能够以微生物燃料电池的阳极作为唯一的电子受体完成有机物的氧化,在产电的同时获得自身生长所需的能量。基于产电菌的特殊代谢方式,有望在处理有机废水的过程中获取电能。分离和培养产电菌是研究其产电过程的基础。本研究采用双层平板技术从厌氧颗粒污泥中分离出数个产电菌株,采用循环伏安法（cyclic voltammograms,CV）对厌氧培养的产电菌进行曲线扫描,所得曲线表明这些产电菌具有一定的电化学活性,可以用来进行产电实验。     

单室无膜空气阴极微生物燃料电池处理沼液的研究

构建了空气阴极无膜微生物燃料电池(microbial fuel cells,MFCs),以石墨毡作为阴阳极材料,以玉米秸秆厌氧发酵沼液为底物,考察了MFCs的产电性能。结果表明:以沼液为底物的MFCs可连续产电。在一定范围内,输出功率与底物浓度的关系符合莫诺方程,最大功率密度为(271±23)mW·m-2,约为处理醋酸钠废水时的61%((444±27)阶级mW·m-2),内阻大小为53～150,与发酵时物料浓度成反比,与发酵时间成正比;MFCs处理沼液的平均库伦效率为(10±1)%,约为处理醋酸钠时的一半((20±2)%);底物的COD去除率为88%～92%,其中挥发性有机酸(VFA)的去除率大于96%。实验表明利用MFCs处理沼液是可行的,沼液中难降解颗粒和复杂有机物的水解作用导致MFCs功率密度及库伦效率相对较低,但未影响COD去除。     

直接微生物燃料电池阴极的制备及优化

研究了直接微生物燃料电池阴极的制备方法,考察了制备过程中的主要影响因素,并通过功率密度曲线及伏安曲线对不同条件下制备的阴极性能进行了评价. 结果表明,防渗层中聚四氟乙烯含量、催化层中Nafion含量及整平层碳含量对阴极性能均有较大影响,当聚四氟乙烯浓度为30%及Nafion含量为2.8 mL、碳含量为0.18 g时,阴极性能最好,此时微生物燃料电池的输出功率密度为357 mW/m2, COD去除率达到90%.     

单室直接微生物燃料电池的阴极制作及构建

在研制含铁离子阴极电极板的基础上,构建了单室直接微生物燃料电池. 通过实验考察了单室无介体微生物燃料电池的产电规律及阴极板中铁离子含量对产电的影响. 实验证明,单室直接微生物燃料电池是可行的,电能的输出主要依赖吸附在电极表面的细菌形成的生物膜,而与悬浮在溶液中的细菌及溶液中的其他物质基本无关. 在单室无介体微生物燃料电池的阴极板中添加铁离子,通过铁离子在二价和三价间的循环转化,提高了电子的传递速率,加快了质子和氧气的反应,电池的输出功率达到14.58 mW/m2.     

A Solid-polymer Electrolyte Direct Methanol Fuel Cell with a Methanol-tolerant Cathode and its Mathematical Modelling

Solid-polymer electrolyte direct methanol fuel cells (SPE-DMFCs) employing carbon-supported Pt–Fe as oxygen-reduction catalyst to mitigate the effect of methanol on cathode performance while operating with oxygen or air have been assembled. These SPE-DMFCs provided maximum power densities of 250 and 120 mW cm^–2 at 85 °C on operating with oxygen and air, respectively. The polarization data for the SPE-DMFCs and their constituent electrodes have also been derived numerically employing a model based on phenomenological transport equations for the catalyst layer, diffusion layer and the membrane electrolyte.     

Electricity Generation and Wastewater Treatment of Oil Refinery in Microbial Fuel Cells Using Pseudomonas putida

Microbial fuel cells (MFCs) represent a novel platform for treating wastewater and at the same time generating electricity. Using Pseudomonas putida (BCRC 1059), a wild-type bacterium, we demonstrated that the refinery wastewater could be treated and also generate electric current in an air-cathode chamber over four-batch cycles for 63 cumulative days. Our study indicated that the oil refinery wastewater containing 2213 mg/L (ppm) chemical oxygen demand (COD) could be used as a substrate for electricity generation in the reactor of the MFC. A maximum voltage of 355 mV was obtained with the highest power density of 0.005 mW/cm² in the third cycle with a maximum current density of 0.015 mA/cm² in regard to the external resistor of 1000 Ω. A maximum coulombic efficiency of 6 × 10⁻²% was obtained in the fourth cycle. The removal efficiency of the COD reached 30% as a function of time. Electron transfer mechanism was studied using cyclic voltammetry, which indicated the presence of a soluble electron shuttle in the reactor. Our study demonstrated that oil refinery wastewater could be used as a substrate for electricity generation.     

Visualization of Biosurfactant Film Flow in a Bacillus subtilis Swarm Colony on an Agar Plate

Collective bacterial dynamics plays a crucial role in colony development. Although many research groups have studied the behavior of fluidic swarm colonies, the detailed mechanics of its motion remains elusive. Here, we developed a visualization method using submicron fluorescent beads for investigating the flow field in a thin layer of fluid that covers a Bacillus subtilis swarm colony growing on an agar plate. The beads were initially embedded in the agar plate and subsequently distributed spontaneously at the upper surface of the expanding colony. We conducted long-term live cell imaging of the B. subtilis colony using the fluorescent tracers, and obtained high-resolution velocity maps of microscale vortices in the swarm colony using particle image velocimetry. A distinct periodic fluctuation in the average speed and vorticity of flow in swarm colony was observed at the inner region of the colony, and correlated with the switch between bacterial swarming and growth phases. At the advancing edge of the colony, both the magnitudes of velocity and vorticity of flow in swarm colony were inversely correlated with the spreading speed of the swarm edge. The advanced imaging tool developed in this study would facilitate further understanding of the effect of micro vortices in swarm colony on the collective dynamics of bacteria.     

Reduction of graphene oxide by an <Emphasis Type="Italic">in-situ</Emphasis> photoelectrochemical method in a dye-sensitized solar cell assembly

Reduction of graphene oxide [GO] has been achieved by an in-situ photoelectrochemical method in a dye-sensitized solar cell [DSSC] assembly, in which the semiconductor behavior of the reduced graphene oxide [RGO] is controllable. GO and RGO were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscope, and Fourier-transform infrared spectroscopy. It was found that the GO film, which assembled in the DSSC assembly as the counter electrode, was partly reduced. An optimized photoelectrochemical assembly is promising for modulating the reduction degree of RGO and controlling the band structure of the resulting RGO. Moreover, this method appeared to be a green progress for the production of RGO electrodes.     

Anti-TMV Activity of Malformin A1, a Cyclic Penta-Peptide Produced by an Endophytic Fungus Aspergillus tubingensis FJBJ11

Plant-associated microorganisms are known to produce a variety of metabolites with novel structures and interesting biological activities. An endophytic fungus FJBJ11, isolated from the plant tissue of Brucea javanica (L.) Merr. (Simaroubaceae), was proven to be significantly effective in producing metabolites with anti-Tobacco mosaic virus (TMV) activities. The isolate was identified as Aspergillus tubingensis FJBJ11 based on morphological characteristics and ITS sequence. Bioassay-guided isolation led to the identification of a cycli penta-peptide, malformin A₁, along with two cyclic dipeptides, cyclo (Gly-l-Pro) and cyclo (Ala-Leu). Malformin A₁ showed potent inhibitory effect against the infection and replication of TMV with IC₅₀ values of 19.7 and 45.4 μg·mL⁻¹, as tested using local lesion assay and leaf-disc method, respectively. The results indicated the potential use of malformin A₁ as a leading compound or a promising candidate of new viricide.     

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In addition, its simple chemical structure and high oxygen content result in soot-free combustion in engines. Fuel injection of DME can be achieved through both conventional mechanical and current common-rail systems but requires slight modification of the standard system to prevent corrosion and overcome low lubricity. The spray characteristics of DME enable its application to compression-ignition engines despite some differences in its properties such as easier evaporation and lower density. Overall, the low particulate matter production of DME provides adequate justification for its consideration as a candidate fuel in compression-ignition engines. Recent research and development shows comparable output performance to a diesel fuel led engine but with lower particulate emissions. NO_x emissions from DME-fuelled engines can meet future regulations with high exhaust gas recirculation in combination with a lean NO_x trap. Although more development work has focused on medium or heavy-duty engines, this paper provides a comprehensive review of the technical feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engines independent of size or application.     

Chitin and chitosan in selected biomedical applications

Chitin (CT), the well-known natural biopolymer and chitosan (CS) (bio-based or “artificial polymer”) are non-toxic, biodegradable and biocompatible in nature. The advantages of these biomaterials are such that, they can be easily processed into different forms such as membranes, sponges, gels, scaffolds, microparticles, nanoparticles and nanofibers for a variety of biomedical applications such as drug delivery, gene therapy, tissue engineering and wound healing. Present review focuses on the diverse applications of CT and CS membranes and scaffolds for drug delivery, tissue engineering and targeted regenerative medicine. The chitinous scaffolds of marine sponges’ origin are discussed here for the first time. These CT based scaffolds obtained from Porifera possess remarkable and unique properties such as hydration, interconnected channels and diverse structural architecture. This review will provide a brief overview of CT and CS membranes and scaffolds toward different kinds of delivery applications such as anticancer drug delivery, osteogenic drug delivery, and growth factor delivery, because of their inimitable release behavior, degradation profile, mucoadhesive nature, etc. The review also provides an overview of the key features of CT and CS membranes and scaffolds such as their biodegradability, cytocompatibility and mechanical properties toward applications in tissue engineering and wound healing.