Microbial fuel cells (MFCs) have attracted considerable interest due to their potential in renewable electrical power generation using the broad diversity of biomass and organic substrates. However, ...the difficulties in achieving high power densities and commercially affordable electrode materials have limited their industrial applications to date. Carbon materials, which can exhibit a wide range of different morphologies and structures, usually possess physiological activity to interact with microorganisms and are therefore fast‐emerging electrode materials. As the anode, carbon materials can significantly promote interfacial microbial colonization and accelerate the formation of extracellular biofilms, which eventually promotes the electrical power density by providing a conductive microenvironment for extracellular electron transfer. As the cathode, carbon‐based materials can function as catalysts for the oxygen‐reduction reaction, showing satisfying activities and efficiencies nowadays even reaching the performance of Pt catalysts. Here, first, recent advancements on the design of carbon materials for anodes in MFCs are summarized, and the influence of structure and surface functionalization of different types of carbon materials on microorganism immobilization and electrochemical performance is elucidated. Then, synthetic strategies and structures of typical carbon‐based cathodes in MFCs are briefly presented. Furthermore, future applications of carbon‐electrode‐based MFC devices in the energy, environmental, and biological fields are discussed, and the emerging challenges in transferring them from laboratory to industrial scale are described.
Carbon‐based electrodes with different morphologies and structures are widely used in microbial fuel cells from conductive supports (anode) to active catalysts (cathode). Recent advancements in the design of carbon materials for anodes (conductivity, biofilm formation, interaction) and cathodes (catalytic activity) are discussed separately. The future perspectives and emerging challenges of this area are also highlighted.
Two types of templates, an active metal salt and silica nanoparticles, are used concurrently to achieve the facile synthesis of hierarchical meso/microporous FeCo‐Nx‐carbon nanosheets ...(meso/micro‐FeCo‐Nx‐CN) with highly dispersed metal sites. The resulting meso/micro‐FeCo‐Nx‐CN shows high and reversible oxygen electrocatalytic performances for both ORR and OER, thus having potential for applications in rechargeable Zn–air battery. Our approach creates a new pathway to fabricate 2D meso/microporous structured carbon architectures for bifunctional oxygen electrodes in rechargeable Zn–air battery as well as opens avenues to the scale‐up production of rationally designed heteroatom‐doped catalytic materials for a broad range of applications.
Meso/microporous Fe/Co‐Nx‐doped carbon nanosheets prepared by an active salt/silica nanoparticle templating approach achieve high performance as bifunctional oxygen electrodes. The FeCo‐Nx‐carbon has a well‐defined 2D morphology and homogenous metal‐atom doping, yielding enriched active sites for ORR‐OER. These features lead to excellent reversible oxygen electrocatalytic performance for Zn–air batteries.
In this paper, a new class of filtering differential phase shifters is proposed and developed, which can provide constant phase shift and self-embedded filtering function at the same time. In ...contrast to its traditional counterparts, the proposed phase shifter consists of two bandpass filter (BPF) branches and the phase properties of generalized nth-order BPF network are systematically studied at first time. With derived closed-form formula of phase slope, the synthesis method is presented to design the proposed filtering differential phase shifters with prescribed arbitrary phase shift value, passband ripple, and bandwidth. The filter order, which dominates frequency selectivity, is considered in the synthesis design of proposed phase shifter as well. The tradeoff between the frequency selectivity and phase shift is discussed. In addition to the advanced features of multifunction and simple geometry, the proposed filtering differential phase shifters can achieve compact size, low amplitude imbalance, and multiway polyphase capability. To validate the proposed concept and synthesis method, two filtering differential phase shifters with single-phase (90°) and five-way polyphase (45°, 90°, 135°, and 180°) are designed, fabricated, and measured. The simulated and measured results coincide well with the prescribed performances in phase shift and magnitude.
•3D high-efficient GO based gels were prepared via the promotion of biopolymers.•The obtained gels have interconnected 3D porous network and large adsorption capacity.•The adsorption process to ...methylene blue was systematically studied and discussed.•The GO-biopolymer gels showed good selective adsorbability to cationic dyes.
Recent studies showed that graphene oxide (GO) presented high adsorption capacities to various water contaminants. However, the needed centrifugation after adsorption and the potential biological toxicity of GO restricted its applications in wastewater treatment. In this study, a facile method is provided by using biopolymers to mediate and synthesize 3D GO based gels. The obtained hybrid gels present well-defined and interconnected 3D porous network, which allows the adsorbate molecules to diffuse easily into the adsorbent. The adsorption experiments indicate that the obtained porous GO-biopolymer gels can efficiently remove cationic dyes and heavy metal ions from wastewater. Methylene blue (MB) and methyl violet (MV), two cationic dyes, are chosen as model adsorbates to investigate the adsorption capability and desorption ratio; meanwhile, the influence of contacting time, initial concentration, and pH value on the adsorption capacity of the prepared GO-biopolymer gels are also studied. The GO-biopolymer gels displayed an adsorption capacity as high as 1100mg/g for MB dye and 1350mg/g for MV dye, respectively. Furthermore, the adsorption kinetics and isotherms of the MB were studied in details. The experimental data of MB adsorption fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm, and the results indicated that the adsorption process was controlled by the intraparticle diffusion. Moreover, the adsorption data revealed that the porous GO-biopolymer gels showed good selective adsorbability to cationic dyes and metal ions.
Functional graphene nanomaterials (FGNs) are fast emerging materials with extremely unique physical and chemical properties and physiological ability to interfere and/or interact with bioorganisms; ...as a result, FGNs present manifold possibilities for diverse biological applications. Beyond their use in drug/gene delivery, phototherapy, and bioimaging, recent studies have revealed that FGNs can significantly promote interfacial biointeractions, in particular, with proteins, mammalian cells/stem cells, and microbials. FGNs can adsorb and concentrate nutrition factors including proteins from physiological media. This accelerates the formation of extracellular matrix, which eventually promotes cell colonization by providing a more beneficial microenvironment for cell adhesion and growth. Furthermore, FGNs can also interact with cocultured cells by physical or chemical stimulation, which significantly mediate their cellular signaling and biological performance. In this review, we elucidate FGNs-bioorganism interactions and summarize recent advancements on designing FGN-based two-dimensional and three-dimensional architectures as multifunctional biological platforms. We have also discussed the representative biological applications regarding these FGN-based bioactive architectures. Furthermore, the future perspectives and emerging challenges will also be highlighted. Due to the lack of comprehensive reviews in this emerging field, this review may catch great interest and inspire many new opportunities across a broad range of disciplines.
Investigations on nonlinear optics are active, with the applications in the modulators, fiber lasers, optical sensors, etc. In this paper, we focus our attention on a system for the ultra-short ...pulses in an inhomogeneous multi-component nonlinear optical medium. Starting from the existing Lax pair and one-fold Darboux transformation (DT), we construct the N-fold DT of that system, which involves N distinct spectral parameters, where N is a positive integer. The N-fold generalized DT with one spectral parameter is obtained through resorting to the Taylor-series-expansion coefficients of a special solution to that Lax pair. Double-pole soliton solutions of that system are derived via that N-fold generalized DT with N=2. With the aid of the N-fold DT, an N-fold Darboux matrix is constructed, based on which the multi-pole soliton solutions in the determinant form with respect to the electromagnetic field E are determined. Graphically, we find that those double-pole soliton solutions are a kind of the bound-state soliton solutions which represent the elastic interactions between the two solitons. Effects of the coefficients in that system on the double-pole soliton are shown via choosing the trigonometric, linear and quadratic functions. Furthermore, we present the triple-pole soliton and quadruple-pole soliton with respect to E. Our results might be useful in understanding the ultra-short pulses in the nonlinear optical media.
Grid-connected inverters are key components of distributed generation systems (DGSs) and micro-grids (MGs), because they are effective interfaces for renewable and sustainable distributed energy ...resources (DERs). Recently, multi-functional grid-connected inverters (MFGCIs) have attracted more and more attention for their benefits on auxiliary services on power quality enhancement in DGSs and MGs. These kinds of converters can not only achieve the power generation of DERs, but also can perform as power quality conditioners at their grid-connected points. It should be noted that these functionalities are optimally organized in the same device, which can significantly enhance the cost-effective feature of the grid-connected inverter, as well as can decrease the investment and bulk compared with multiple devices with independent functionalities. MFGCIs are especially suitable for DGSs and MGs application due to their good performances and benefits. Topologies and control strategies of MFGCIs are comprehensively reviewed in this paper. Additionally, detailed explanation, comparison, and discussion on MFGCIs are achieved. Furthermore, some future research fields on MFGCIs are well summarized.
•Physical properties of fuel influence the spray flame structure.•Rapeseed biodiesel (RME) and Jet-A1 spray flames show similar flow field.•RME spray flame shows larger droplet size and higher volume ...flux compared to Jet-A1.•The flame reaction zone for RME spray flame is more intense locally.
The spray combustion characteristics of rapeseed methyl esters (RME) were compared to Jet-A1 fuel using a gas turbine type combustor. The swirling spray flames for both fuels were established at a constant power output of 6kW. The main swirling air flow was preheated to 350°C prior to coaxially enveloping the airblast-atomized liquid fuel spray at atmospheric pressure. Investigation of the fundamental spray combustion was performed via measurements of the fuel droplet sizes and velocities, gas phase flow fields and flame reaction zones. The spray flame droplets and flow fields in the combustors were characterised using phase Doppler anemometry (PDA) and particle imaging velocimetry (PIV) respectively. Flame chemiluminescence imaging was employed to identify the flame reaction zones. The highest droplet concentration zone extends along a 30° angle from the symmetry axis, inside the flame zone. Only small droplets(<17μ) (<17μm)are found around the centreline region, while larger droplets are found at the edge of the spray outside the flame reaction zone. RME exhibits spray characteristics similar to Jet-A1 but with droplet concentration and volume fluxes four times higher, consistent with the expected longer droplet evaporation timescale. The flow field characteristics for both RME and Jet-A1 spray flames are very similar despite the significantly different visible characteristics of the flame reaction zones.
•Combustion characteristics of limonene, Jet A-1, and blends are investigated.•Tested in a swirl stabilized combustor at different swirl air temperatures.•Maximum OH* and CH* intensities are observed ...near the dump plane of the combustor.•The flame temperature profile is in accordance with the loading % of limonene.•CO and NOx emissions decrease with an increase in the % of limonene in the blends.
Biofuels are low carbon fuels and have emerged as an important source of energy for reducing pollutant emissions and greenhouse gas emissions in the aviation industry. In the present work, the spray combustion characteristics of limonene, Jet A-1, and limonene/Jet A-1 blends (10%, 30%, and 50% volumetric loading of limonene) have been experimentally investigated in a laboratory-scale swirl-stabilized combustor. To examine the effect of heated swirling air on the combustion of limonene, Jet A-1, and Jet A-1/limonene blends, the experiment has been conducted on non-preheat and two preheat conditions (swirling air temperature of 373 K and 473 K). Limonene is considered an emerging fuel alternative owing to its high calorific value and comparable physical properties with Jet A-1. The spray flame length of limonene is approximately 20% shorter than the flame of Jet A-1, while compared to the non-preheated case the flame length is reduced in preheat case (approximately 15% reduction in 373 K case and 25% reduction at 473 K). Compared to pure Jet A-1, the flames of limonene and limonene/Jet A-1 blends have given good results in terms of pollutant emissions and temperature profiles when limonene is added to Jet A-1. 50% limonene-loaded blends show a drop of 15% CO and neat limonene show a 35 % CO reduction. Additionally, 10%, 30%, and 50% limonene blends have shown better combustion characteristics compared to neat Jet A-1.
•Horse manure is thermogravimetrically analysed at 1–10 °C/min under inert environment.•The TGA data is analysed using model-free FWO, KAS, Friedman and Kissinger methods.•The determined activation ...energy for horse manure is between 149 and 200 kJ/mol.•Horse manure shows highest conversion rate at pyrolysis temperature of 290–330 °C.•FWO, KAS and Friedman methods are reliable in determining the kinetic parameters.
Horse manure is a biowaste with bioenergy recovery potential for heat and power generation. However, there is no kinetics data in literature to date. In this work, a kinetic study of the pyrolysis process of horse manure is investigated through the use of thermogravimetric analyses. The samples were heated over a range of temperature from 298 to 927 K with four different heating rates of 1, 2, 5 and 10 K/min. The weight loss was measured by a thermogravimetric analyser in an inert atmosphere. The differential thermal gravimetric (DTG) thermogram shows that the highest reaction rate occurred at between 290.2 and 329.6 °C where the devolatilisation process was initiated to overcome the activation energy barrier of the manure. The activation energy and pre-exponential factor obtained by the Kissinger method, assumed to be constant throughout the whole pyrolysis process are 149 kJ/mol and 3.3 × 1012 s−1, respectively. The activation energy calculated from the non-isothermal Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods are 199.3, 200.2 and 194.6 kJ/mol, whereas the pre-exponential values are 9.3 × 1018, 1.8 × 1019 and 3.6 × 1020 s−1, respectively. The kinetic parameters determined based on interval conversional fraction shows good agreement. The high volatile and low ash content in horse manure indicates the potential for bioenergy recovery. The results of the kinetic study can be used for modelling devolatilisation and designing thermochemical conversion processes.
