Microbial fuel cells, in which living microorganisms convert chemical energy into electricity, represent a potentially sustainable energy technology for the future. Here we report the single-bacterium level current measurements of Geobacter sulfurreducens DL-1 to elucidate the fundamental limits and factors determining maximum power output from a microbial fuel cell. Quantized stepwise current outputs of 92(+ or -33) and 196(+ or -20) fA are generated from microelectrode arrays confined in isolated wells. Simultaneous cell imaging/tracking and current recording reveals that the current steps are directly correlated with the contact of one or two cells with the electrodes. This work establishes the amount of current generated by an individual Geobacter cell in the absence of a biofilm and highlights the potential upper limit of microbial fuel cell performance for Geobacter in thin biofilms.

关键词：细菌；;电流；电化学；电极

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In the five years of this MURI program, we have made major advances in several areas, including: (1) power production optimization; (2) MFC design; (3) identification of the genes coding for the proteins involved with electricity production by Shewanella oneidensis (MR-1); (4) construction of conceptual models of extracellular electron transport (EET); (5) characterization and quantification of the per cell rates of EET to solid substrates; (6) characterization of a previously undescribed behavioral adaptation of microbes to charged surfaces called electrokinesis (and the impact of surface charge on bacterial attachment and biofilm formation); (7) the use of Vertical Scanning Interferometry for cell and biofilm analyses; (8) the design and implementation of a new type of (Deep Ultraviolet Light) microscope for non-invasive studies of microbes on surfaces; (9) detailed biophysical studies of the mechanism of electron transfer in conductive appendages called bacterial nanowires, produced by MR-1 and other Shewanella strains and species; (10) characterization of the selective advantages of Shewanella cells in late stationary phase, and the relationship of this metabolic state to the long term function of MFC systems; and, (11) characterization of the activities of microbes acting as catalysts on the cathodes of MFC systems. During this time, we published over *** reviewed papers, presented over 100 talks at scientific meetings, and collaborated with colleagues from around the world.

关键词：电力；微生物；纳米线；生物物理学；电子传递

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Photonic structures can exhibit significant absorption enhancement when an object s length scale is comparable to or smaller than the wavelength of light. This property has enabled photonic structures to be an integral component in many applications such as solar cells, light emitting diodes, and photothermal therapy. To characterize this enhancement at the single particulate level, conventional methods have consisted of indirect or qualitative approaches which are often limited to certain sample types. To overcome these limitations, we used a bilayer cantilever to directly and quantitatively measure the spectral absorption efficiency of a single silicon microwire in the visible wavelength range. We demonstrate an absorption enhancement on a per unit volume basis compared to a thin film, which shows good agreement with Mie theory calculations. This approach offers a quantitative approach for broadband absorption measurements on a wide range of photonic structures of different geometric and material compositions.

关键词：吸收光谱；光热性质；定量分析；宽带

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The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps.

关键词：氩;宇宙介子；热量计；;电磁场；;电子

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This paper describes a computational fluid dynamic method used for modelling changes in aircraft geometry due to icing. While an aircraft undergoes icing, the accumulated ice results in a geometric alteration of the aerodynamic surfaces. In computational simulations for icing, it is necessary that the corresponding geometric change is taken into consideration. The method used, herein, for the representation of the geometric change due to icing is a non-cut cell Immersed Boundary Method (IBM). Computational cells that are in a body fitted grid of a clean aerodynamic geometry that are inside a predicted ice formation are identified. An IBM is then used to change these cells from being active computational cells to having properties of viscous solid bodies. This method has been implemented in the NASA developed node centered, finite volume computational fluid dynamics code, FUN3D. The presented capability is tested for two-dimensional airfoils including a clean airfoil, an iced airfoil, and an airfoil in harmonic pitching motion about its quarter chord. For these simulations velocity contours, pressure distributions, coefficients of lift, coefficients of drag, and coefficients of pitching moment about the airfoil's quarter chord are computed and used for comparison against experimental results, a higher order panel method code with viscous effects, XFOIL, and the results from FUN3D's original solution process. The results of the IBM simulations show that the accuracy of the IBM compares satisfactorily with the experimental results, XFOIL results, and the results from FUN3D's original solution process.

关键词：空气动力系数；空气阻力；边界；计算流体动力学

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Heat transfer of phase change material (PCM) in an open cell micro- foam structure was numerically studied. A high constant temperature was specified at the top surface of the structure. Each unit of the micro-foam is a body-centered-cubic (BCC) lattice embedded with spherical micro-pores. Two different simulation methodologies were applied. One is the high-fidelity direct numerical simulation (DNS), which allows for the effective thermo- physical parameters to be derived. The other methodology is a volume-averaged simulation based on one- and two-temperature models. Our results show that the volume-averaged simulation can accurately and efficiently capture the phase change process in PCM/micro-foam systems, with the effective thermal conductivity derived from direct simulations and expressed as a power law of porosity.

关键词：储电池；储能材料；热转化

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The high pressure, high temperature sapphire cell was designed to provide users at the Spallation Neutron Source the ability to do in-situ supercritical bulk water studies.

关键词：蓝宝石；中子源；散射；约束

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Carbon-coated magnetite nanoparticles (NPs) were synthetized by the mechanochemical method with hematite as precursor and amorphous carbon as inorganic reductor. After 18 hours of milling in an inert atmosphere, a nanocomposite material of magnetite and carbon was obtained. Structural and magnetic properties of the NPs were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometry. XRD patterns, refined with the Rietveld method, show that magnetite is present in samples milled from 6 hours onward and that after milling for 18 hours and annealing in Ar, the sample contains a single crystalline phase. Magnetization curves for samples with different milling times show saturation magnetization values that range from 34.1 emu/g after 1 h to 78.0 emu/g after 18 h. Coercive fields are about 500 Oe for all samples. TEM studies reveal that the samples are made of amorphous carbon clusters with magnetite NPs of 20 nm. The obtained NPs, associated to electrochemical transducers, show an improved enhancement of the charge transfer for redox processes involving different bioanalytes. Thus, these NPs offer unique properties as a catalyst in biosensing strategies for the electrochemical detection of high-impact markers and the development of theranostics smart-devices for biomedical applications.

关键词：电池；电能；纳米颗粒

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Titanium dioxide has been used as the white pigment since the ancient times.95% of its current usage in industry involves paints, cosmetics, plastics, paper, and food. However, in near future the economic impact of titanium dioxide seems to be controlled by energy related applications mostly. Therefore, this chapter projects a brief outlook on the added value provided by the titanium dioxide structures in new and emerging technologies of the energy sector. The applications focused are: solar fuels, solar cells, fuel cells, Li ion batteries and solid state lighting. In those applications, TiO_2 standouts with its chemical and thermal stability, morphology variety, position of conduction and valance band energy levels, optical properties and cost.

关键词：二氧化钛；新兴能源技术；聚焦

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Magnetic nanoparticles and nanocomposites have been special focus of high research interest due to their high magnetic moment and bio-affinity surface properties and promising applications in nanoscience, nanotechnology and bio-applications. These properties can be obtained by synthesizing various magnetic nanoparticles and core-shell type magnetic nanocomposites. In this research, we synthesized high magnetization superparamagnetic nanoparticles and core-shell nanocomposites by chemical and sonochemical method for using as carriers/labels in bio-sensing purpose. Iron oxide magnetic nanoparticles (NPs) have been synthesized by sonochemical method using inexpensive and non-toxic metal salts as reactants. Transmission electron microscopy (TEM) data demonstrated that the particles were narrow range in size distribution with 11 nm average particle size and spherical in shape. The magnetization curve from vibrating sample magnetometer (VSM) measurement shows that as-synthesized NPs were nearly superparamagnetic in magnetic properties with very low coercivity, and magnetization values were 80 emu/g. Monodisperse magnetite nanocubes with uniform particle size of about 80 nm have been synthesized in aqueous medium by sonochemical method. The magnetic characterization of the NPs reveals saturation magnetization of 91 emu/g at 5 K for as-synthesized sample and 94.8 emu/g for the sample which annealed at the temperature of 600 °C in a vacuum chamber. However, the saturation magnetization has been observed to decrease with further increase in annealing temperature and this has been attributed to the presence of a thin magnetic dead layer at the surface caused by shape anisotropy distortion and broken exchange bonds, and spin canting on the surface of the particles in addition to formation of a small amount of maghemite phase. Highly crystalline and monodisperse cobalt ferrite (CoFe_2O_4) nanoparticles have been synthesized via rapid one-pot sonochemical techniques and without subsequent calcination. The size of CoFe_2O_4 nanoparticle was controlled in the range from 20 to 110 nm based on the solvent medium used in the synthesis process. Furthermore, the evolution from spherical to cubic morphology of cobalt ferrite is achieved by simply changing the solvent medium from aqueous to alcoholic medium. High saturation magnetization (Ms) and high coercivity (Hc) values of 87 emu/g and 1610 Oe, respectively were obtained for the CoFe_2O_4 NPs. For synthesis of core-shell type of silica coated iron oxide magnetic (Fe_3O_4@SiO_2 core-shell) NPs, sono-chemical approach was applied using inexpensive and non-toxic chemicals. TEM data demonstrated that the thickness of silica coating on iron oxide magnetic NPs 10-15 nm in average. The magnetization curve from VSM measurement shows that the magnetization has also been decreased of as synthesized silica coated iron oxide NPs compared to freshly prepared bare iron oxide magnetic NPs, which is also a evidence of synthesizing of Fe_3O_4@SiO_2 core-shell NPs. Besides the synthesis of metal oxide core-shell NPs, high magnetization FeCo nanoparticles with different Fe/Co ratios have been successfully synthesized by surfactant free simple modified polyol method. In this process, polyethylene glycol was used as a solvent media and it has been found to play a key role to act as a reducing agent as well as a stabilizer simultaneously. TEM data suggest that the annealed FeCo nanoparticles are of 50-90 nm in size. The physical Property Measurement System (PPMS) reveals that the Fe_(60)Co_(40) composition among all the samples exhibit highest saturation magnetization of 230.14 emu/g at 5K. In another study, high magnetic monodisperse NiFe NPs with different compositions have been successfully synthesized polyol method. TEM images displayed formation of a thin oxide layer around the nanoparticles, and confirmed by detection of some oxygen element using EDS measurement. The magnetic properties of the synthesized NiFe NPs samples were measured VSM at room temperature, and the saturation magnetization value was found to be iron content dependent.

关键词：纳米粒子；磁性纳米颗粒；纳米复合材料

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