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排序方式: 共有350条查询结果,搜索用时 828 毫秒
81.
通过脉冲腐蚀法对硅片进行多孔硅的制备,利用玻片通过对共价法、离子吸附法和APTES修饰的戊二醛交联法3种固定适配子方法的对比,以确定较好的固定青霉素适配子的方法。将适配子固定在多孔硅上后,利用交流阻抗法对加入青霉素前后传感器阻抗值进行测定、对比,构建等效电路并进行阻抗拟合。对多孔硅传感器的Nyqu ist谱图进行分析以确定多孔硅表面成功固定了青霉素适配子,从而证明构建纳米生物传感器成功。传感器的线性检测范围为0.05~0.2 mg/L,检测限为0.05 mg/L。 相似文献
82.
Sarah J. Vogt Alexis B. Sanderlin Joseph D. Seymour Sarah L. Codd 《Biotechnology and bioengineering》2013,110(5):1366-1375
Biofilm growth in porous media is difficult to study non‐invasively due to the opaqueness and heterogeneity of the systems. Magnetic resonance is utilized to non‐invasively study water dynamics within porous media. Displacement‐relaxation correlation experiments were performed on fluid flow during biofilm growth in a model porous media of mono‐dispersed polystyrene beads. The spin–spin T2 magnetic relaxation distinguishes between the biofilm phase and bulk fluid phase due to water–biopolymer interactions present in the biofilm, and the flow dynamics are measured using PGSE NMR experiments. By correlating these two measurements, the effects of biofilm growth on the fluid dynamics can be separated into a detailed analysis of both the biofilm phase and the fluid phase simultaneously within the same experiment. Within the displacement resolution of these experiments, no convective flow was measured through the biomass. An increased amount of longitudinal hydrodynamic dispersion indicates increased hydrodynamic mixing due to fluid channeling caused by biofilm growth. The effect of different biofilm growth conditions was measured by varying the strength of the bacterial growth medium. Biotechnol. Bioeng. 2013; 110: 1366–1375. © 2012 Wiley Periodicals, Inc. 相似文献
83.
Microbial souring (H2S production) in porous medium was investigated in an anaerobic upflow porous medium reactor at 60°C using produced waters obtained from the North Sea Ninian oilfield as the inoculum. Multiple carbon sources commonly found in oil field waters (formate, acetate, propionate, iso‐ and n‐butyrates) with inorganic sulfate as the electron acceptor were used as the substrates. Stoichiometry and the rate of souring in the reactor column were calculated. A large proportion of H2S was trapped in the column as FeS and possibly as a gas phase. Concentration gradients for the substrates (organic acids and sulfate) and H2S were generated along the column. At steady state, the highest volumetric substrate consumption and H2S production were found at the front part (inlet) of the reactor column. The average volumetric sulfate reduction rate after H2S production had stabilized was calculated to be 203 ± 51 mg sulfate‐S.l‐1.d‐1. Comparison of the results with the authors’ previous work on the Alaska Kuparuk oilfield waters indicates that the two different microbial inocula (produced waters) exhibited the same experimental trends (rates and location) for souring in the experimental reactor system. This indicates that abiotic factors, as well as microbial parameters, may play an important role for microbial souring in the system. 相似文献
84.
Theiler S Mela P Diamantouros SE Jockenhoevel S Keul H Möller M 《Biotechnology and bioengineering》2011,108(3):694-703
The potential of novel functional star‐shaped poly(ε‐caprolactone)s of controlled molecular weight and low molecular weight distribution bearing acrylate end groups as material for biomedical applications was demonstrated in this study. The polymers were functionalized via Michael‐type addition of amino acid esters containing amino or thiol groups showing the potential for immobilization of biomolecules. Furthermore, scaffolds of different geometries were prepared by uniaxial freezing of polymer solutions followed by freeze drying. Different solvents and polymer concentrations were investigated, resulting in scaffolds with porosities between 76 and 96%. Mechanical properties of the scaffolds were investigated and the morphology was determined via scanning electron microscopy. Scaffolds with interconnected channels were prepared using benzene, 1,2‐dichloroethane or dioxane as solvent. The tubular longitudinal pores in honeycomb arrangement extend throughout the full extent of the scaffolds (typical pore sizes: 20–100 µm). Biotechnol. Bioeng. 2011; 108:694–703. © 2010 Wiley Periodicals, Inc. 相似文献
85.
Xiaoxiao Huang Tong Shen Teng Zhang Hailong Qiu Xingxing Gu Zeeshan Ali Yanglong Hou 《Liver Transplantation》2020,10(11)
Developing substitutes of noble metal catalysts toward oxygen reduction reaction (ORR) at the cathode is of vital importance for promoting low‐temperature polymer electrolyte membrane fuel cells. Transition metal species have been one of the hot areas of interest due to their low cost, high activity, and long‐term stability. The design of porous carbon nanostructures decorated with transition metal species plays a vital role in enhancing ORR catalytic performance. Here, the recent breakthroughs in porous carbon nanostructures decorated with transition metal species (including nanoparticles and atomically dispersed supported metal) are discussed. The porous nanostructures can provide large surface area as well as abundant pore channels, leading to sufficient exposure of active sites and efficient mass transfer. These nanostructures can be synthesized by several approaches, including the templated method, the self‐templated method, the impregnation process, and so on. Furthermore, the ORR performance and the exploration of active sites are also discussed for further enhancement of the ORR catalysts. Finally, the challenges and prospects are discussed, which would push forward the development of ORR catalysts in the near future. 相似文献
86.
Rui Wang Jinlong Yang Xin Chen Yan Zhao Wenguang Zhao Guoyu Qian Shunning Li Yinguo Xiao Hao Chen Yusheng Ye Guangmin Zhou Feng Pan 《Liver Transplantation》2020,10(9)
The lithium–sulfur (Li–S) battery is considered a promising candidate for the next generation of energy storage system due to its high specific energy density and low cost of raw materials. However, the practical application of Li–S batteries is severely limited by several weaknesses such as the shuttle effect of polysulfides and the insulation of the electrochemical products of sulfur and Li2S/Li2S2. Here, by doping nitrogen and integrating highly dispersed cobalt catalysts, a porous carbon nanocage derived from glucose adsorbed metal–organic framework is developed as the host for a sulfur cathode. This host structure combines the reported positive effects, including high conductivity, high sulfur loading, effective stress release, fast lithium‐ion kinetics, fast interface charge transport, fast redox of Li2Sn, and strong physical/chemical absorption, achieving a long cycle life (86% of capacity retention at 1C within 500 cycles) and high rate performance (600 mAh g?1 at 5C) for a Li–S battery. By combining experiments and density functional theoretical calculations, it is demonstrated that the well‐dispersed cobalt clusters play an important role in greatly improving the diffusion dynamics of lithium, and enhance the absorption and conversion capability of polysulfides in the host structure. 相似文献
87.
The generation of renewable electricity is variable, leading to periodic oversupply. Excess power can be converted to H2 via water electrolysis, but the conversion cost is currently too high. One way to decrease the cost of electrolysis is to increase the maximum productivity of electrolyzers. This study investigates how nano‐ and microstructured porous electrodes can improve the productivity of H2 generation in a zero‐gap, flow‐through alkaline water electrolyzer. Three nickel electrodes—foam, microfiber felt, and nanowire felt—are studied to examine the tradeoff between surface area and pore structure on the performance of alkaline electrolyzers. Although the nanowire felt with the highest surface area initially provides the highest performance, this performance quickly decreases as gas bubbles are trapped within the electrode. The open structure of the foam facilitates bubble removal, but its small surface area limits its maximum performance. The microfiber felt exhibits the best performance because it balances high surface area with the ability to remove bubbles. The microfiber felt maintains a maximum current density of 25 000 mA cm?2 over 100 h without degradation, which corresponds to a hydrogen production rate 12.5‐ and 50‐times greater than conventional proton‐exchange membrane and alkaline electrolyzers, respectively. 相似文献
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90.
Sol Yun Seong‐Min Bak Sanghyeon Kim Jeong Seok Yeon Min Gyu Kim Xiao‐Qing Yang Paul V. Braun Ho Seok Park 《Liver Transplantation》2019,9(6)
Controlling the internal microstructure and overall morphology of building blocks used to form hybrid materials is crucial for the realization of deterministically designed architectures with desirable properties. Here, integrative spray‐frozen (SF) assembly is demonstrated for forming hierarchically structured open‐porous microspheres (hpMSs) composed of Fe3O4 and reduced graphene oxide (rGO). The SF process drives the formation of a radially aligned microstructure within the sprayed colloidal droplets and also controls the overall microsphere morphology. The spherical Fe3O4/rGO hpMSs contain interconnected open pores, which, when used as a lithium‐ion battery anode, enables them to provide gravimetric and volumetric capacities of 1069.7 mAh g?1 and 686.7 mAh cm?3, much greater than those of samples with similar composition and different morphologies. The hpMSs have good rate and cycling performance, retaining 78.5% capacity from 100 to 1000 mA g?1 and 74.6% capacity over 300 cycles. Using in situ synchrotron X‐ray absorption spectroscopy, the reaction pathway and phase evolution of the hpMSs are monitored enabling observation of the very small domain size and highly disordered nature of FexOy. The reduced capacity fade relative to other conversion systems is due to the good electrical contact between the pulverized FexOy particles and rGO, the overall structural integrity of the hpMSs, and the interconnected open porosity. 相似文献