Efficient Transfer Research Articles

Tailored Metal-Organic Frameworks for Water Purification: Perfluorinated Fe-MOFs for Enhanced Heterogeneous Catalytic Ozonation.

An industrially viable catalyst for heterogeneous catalytic ozonation (HCO) in water purification requires the characteristics of good dispersion of active species on its surface, efficient electron transfer for ozone decay, and maximum active species utilization. While metal-organic frameworks (MOFs) represent an attractive platform for HCO, the metal nodes in the unmodified MOFs exhibit low catalytic activity. Herein, we present a perfluorinated Fe-MOF catalyst by substituting H atoms on the metalated ligands with F atoms (termed 4F-MIL-88B) to induce structure evolution. The Lewis acidity of 4F-MIL-88B was enhanced via the formation of Fe nodes, tailoring the electron distribution on the catalyst surface. As a result of catalyst modification, the rate constant for degradation of the target compounds examined increased by ∼700% compared with that observed for the unmodified catalyst. Experimental evidence and theoretical calculations showed that the modulated polarity and the enhanced electron transfer between the catalyst and ozone molecules contributed to the adsorption and transformation of O3 to •OH on the catalyst surface. Overall, the results of this study highlight the significance of tailoring the metalated ligands to develop highly efficient and stable MOF catalysts for HCO and provide an in-depth mechanistic understanding of their structure-function evolution, which is expected to facilitate the applications of nanomaterial-based processes in water purification.

Exploring Nitric Oxide as a Regulator in Salt Tolerance: Insights into Photosynthetic Efficiency in Maize.

The growing issue of salinity is a significant threat to global agriculture, affecting diverse regions worldwide. Nitric oxide (NO) serves as an essential signal molecule in regulating photosynthetic performance under physiological and stress conditions. The present study reveals the protective effects of different concentrations (0-300 µM) of sodium nitroprusside (SNP, a donor of NO) on the functions of the main complexes within the photosynthetic apparatus of maize (Zea mays L. Kerala) under salt stress (150 mM NaCl). The data showed that SNP alleviates salt-induced oxidative stress and prevents changes in the fluidity of thylakoid membranes (Laurdan GP) and energy redistribution between the two photosystems (77K chlorophyll fluorescence ratio F735/F685). Chlorophyll fluorescence measurements demonstrated that the foliar spray with SNP under salt stress prevents the decline of photosystem II (PSII) open reaction centers (qP) and improves their efficiency (Φexc), thereby influencing QA- reoxidation. The data also revealed that SNP protects the rate constants for two pathways of QA- reoxidation (k1 and k2) from the changes caused by NaCl treatment alone. Additionally, there is a predominance of QA- interaction with plastoquinone in comparison to the recombination of electrons in QA QB- with the oxygen-evolving complex (OEC). The analysis of flash oxygen evolution showed that SNP treatment prevents a salt-induced 10% increase in PSII centers in the S0 state, i.e., protects the initial S0-S1 state distribution, and the modification of the Mn cluster in the OEC. Moreover, this study demonstrates that SNP-induced defense occurs on both the donor and acceptor sides of the PSII, leading to the protection of overall photosystems performance (PIABS) and efficient electron transfer from the PSII donor side to the reduction of PSI end electron acceptors (PItotal). This study clearly shows that the optimal protection under salt stress occurs at approximately 50-63 nmoles NO/g FW in leaves, corresponding to foliar spray with 50-150 µM SNP.

Efficient transplacental transfer of SARS-CoV-2 antibodies between naturally exposed mothers and infants in Accra, Ghana

We aimed to determine SARS-CoV-2 antibody seropositivity among pregnant women and the transplacental transfer efficiency of SARS-CoV-2-specific antibodies relative to malaria antibodies among SARS-CoV-2 seropositive mother-cord pairs. This cross-sectional study was conducted in Accra, Ghana, from March to May 2022. Antigen- specific IgG antibodies against SARS-CoV-2 (nucleoprotein and spike-receptor binding domain) and malarial antigens (circumsporozoite protein and merozoite surface protein 3) in maternal and cord plasma were measured by ELISA. Plasma from both vaccinated and unvaccinated pregnant women were tested for neutralizing antibodies using commercial kit. Of the unvaccinated pregnant women tested, 58.12% at antenatal clinics and 55.56% at the delivery wards were seropositive for both SARS-CoV-2 nucleoprotein and RBD antibodies. Anti-SARS-CoV-2 antibodies in cord samples correlated with maternal antibody levels (N antigen rs = 0.7155, p < 0.001; RBD rs = 0.8693, p < 0.001). Transplacental transfer of SARS-CoV-2 nucleoprotein antibodies was comparable to circumsporozoite protein antibodies (p = 0.9999) but both were higher than transfer rates of merozoite surface protein 3 antibodies (p < 0.001). SARS-CoV-2 IgG seropositivity among pregnant women in Accra is high with a boost of SARS-CoV-2 RBD-specific IgG in vaccinated women. Transplacental transfer of anti-SARS-CoV-2 and malarial antibodies was efficient, supporting vaccination of mothers as a strategy to protect infants against SARS-CoV-2.

In2S3 nanoparticles modify the porous Fe2V4O13 nanostructure photoanode to enhance charge separation efficiency and photoelectrochemical water splitting performance

In this study, we demonstrate for the first time a promising photoanode of Fe2V4O13/In2S3 (FVO/IS) nanoparticles (NPs) for photoelectrochemical (PEC) water splitting. Most importantly, this work presents the first application of X-ray photoelectron spectroscopy in tracking electron flow direction within FVO/IS to reveal the formation of heterojunction having the electron flow from IS to FVO. Mott-Schottky measurement confirms that the modification of IS NPs establishes the type II heterojunction between FVO and IS, favorable for the transport and separation of carriers. Spectral measurements of electrochemical impedance spectroscopy, photoluminescence and Bode diagram confirm the effective separation of carriers and the prolongation of the charge lifetime in the FVO/IS heterojunction photoanode. Moreover, the electrochemical measurements evidently demonstrate the substantial enhancement in the charge separation efficiency (ηseparation) and charge transfer efficiency (ηtransfer) of the photoanode, leading to significantly enhanced PEC water splitting capability. As a result, in contrast with the pure FVO NPs photoanode, the photocurrent density of the constructed FVO/IS NPs photoanode is increased by 27 times without bias. This study paves a new approach for boosting the PEC water splitting activity of FVO photoanodes by constructing heterostructures through modification with other semiconductors.

Optimal design of supercritical He–H2 PCHE in SABER system by multi-objective genetic algorithm

A double-circle straight-channel printed circuit heat exchanger (PCHE) was first employed in a synergistic air-breathing rocket engine (SABER) system for supercritical He and H2 heat transfer. The heat transfer mechanism of the supercritical flow in the PCHE channel was numerically analyzed. For considered the pressure drop, heat transfer efficiency, and ratio of heat flux to weight, simultaneously, the design of the PCHE is multi-objective genetic optimized. The results shown that the supercritical H2 flow is chaotic near the pseudo-critical point, which is a coupled effect of buoyancy and gravity. Chaotic flow leads to an asymmetrical temperature distribution, which deteriorates the heat transfer performance. For 27 numerical experimental cases designed using the center composite surface method, the determine factors of the regression models of the three objectives for both cold and hot sides were all above 92 %. The Pareto optimal solutions for the supercritical He - H2 PCHE design and performance were obtained based on the nondominated sorting genetic algorithm II. From a comprehensive view of the three targets, the optimal designs were the A-4 and B-4 solutions for the cold and hot sides, respectively.

Numerical analysis of the heat transfer application on a convective tangent hyperbolic nanofluid flow over a porous stretching cylinder with stratification effects

The nanofluids has attractive applications in the industrials and engineering field because nanofluids offer the improvement in the thermal efficiencies of flow, which is very fruitful in the energy sector. This study emphases on the numerical exploration of heat and mass transfer efficiencies on a mixed convective flow of tangent hyperbolic nanofluid under the consideration of gyrotactic microorganisms. To analyze the magnetized boundary layer flow, the stratification boundary conditions are considered on the surface of the stretching cylinder. The thermal analysis involves the important features such as activation energy, nonuniform heat source/sink, and nonlinear thermal radiation. The flow model is altered into system of nonlinear ordinary differential equations by utilization of suitable similarity variables and Bvp4c solver on the MATLAB to find numerical solutions. The graphical and tabulated investigation is presented for various developing parameters thoroughly. The results indicate that by the increment of mixed convection parameters the fluid velocity accelerate consequently, whereas raising values of the Weissenberg number reduce the fluid velocity. TThe greater values of the Prandtl number lead to a decrease in fluid temperature, while the concentration of nanoparticles rises with the increase in activation energy parameters. Additionally, the heat transfer rate reduces due to stronger values of thermophoresis parameter, although reverse tendency is observed for the greater values of Brownian motion parameter.

Fast collective motions of backbone in transmembrane α helices are critical to water transfer of aquaporin.

Fast collective motions are widely present in biomolecules, but their functional relevance remains unclear. Herein, we reveal that fast collective motions of backbone are critical to the water transfer of aquaporin Z (AqpZ) by using solid-state nuclear magnetic resonance (ssNMR) spectroscopy and molecular dynamics (MD) simulations. A total of 212 residue site-specific dipolar order parameters and 158 15N spin relaxation rates of the backbone are measured by combining the 13C- and 1H-detected multidimensional ssNMR spectra. Analysis of these experimental data by theoretic models suggests that the small-amplitude (~10°) collective motions of the transmembrane α helices on the nanosecond-to-microsecond timescales are dominant for the dynamics of AqpZ. The MD simulations demonstrate that these collective motions are critical to the water transfer efficiency of AqpZ by facilitating the opening of the channel and accelerating the water-residue hydrogen bonds renewing in the selectivity filter region.

The Hera Radio Science Experiment at Didymos

Hera represents the European Space Agency's inaugural planetary defense space mission and plays a pivotal role in the Asteroid Impact and Deflection Assessment international collaboration with NASA DART mission that performed the first asteroid deflection experiment using the kinetic impactor techniques. With the primary objective of conducting a detailed post-impact survey of the Didymos binary asteroid following the DART impact on its small moon called Dimorphos, Hera aims to comprehensively assess and characterize the feasibility of the kinetic impactor technique in asteroid deflection while conducting an in-depth investigation of the asteroid binary, including its physical and compositional properties as well as the effect of the impact on the surface and shape of Dimorphos. In this work, we describe the Hera radio science experiment, which will allow us to precisely estimate critical parameters, including the mass, which is required to determine the momentum enhancement resulting from the DART impact, mass distribution, rotational states, relative orbits, and dynamics of the asteroids Didymos and Dimorphos. Through a multi-arc covariance analysis, we present the achievable accuracy for these parameters, which consider the full expected asteroid phase and are based on ground radiometric, Hera optical images, and Hera to CubeSats InterSatellite Link radiometric measurements. The expected formal uncertainties for Didymos and Dimorphos GM are better than 0.01% and 0.1%, respectively, while their J2 formal uncertainties are better than 0.1% and 10%, respectively. Regarding their rotational state, the absolute spin pole orientations of the bodies can be recovered to better than 1°, and Dimorphos' spin rate to better than 10−3%. Dimorphos reconstructed relative orbit can be estimated at the sub-m level. Preliminary results, using a higher-fidelity dynamical model of the coupled motion between rotational and orbital dynamics, show uncertainties in the main parameters of interest that are comparable to those in standard radio science models. A first-order estimate of the expected uncertainty in the momentum transfer efficiency from DART's impact, obtainable with Hera, yields a value of about 0.25. This represents a significant improvement compared to current estimates. Overall, the retrieved values meet the Hera radio science requirements and goals, and remain valid under the condition that the system is determined to be in an excited but non-chaotic (or tumbling) state. The Hera radio science experiment will play an integral role in the exploration of the Didymos binary asteroid system and will provide unique scientific measurements, which, when combined with other observables such as optical images, altimetry measurements, and satellite-to-satellite tracking of the CubeSats, will support the mission's overarching goals in planetary defense and the deep understanding of binary asteroids.

Anatase TiO2/Defective UiO-66 porous octahedral S-scheme heterojunctions toward optimized photocatalytic performance

Photocatalysis is an alternative for antibiotics removal from wastewater for the sustainable development of human society. However, applying photocatalysts for antibiotics (e.g., tetracycline) degradation under practical conditions is highly restricted by the low reaction efficiency due to the prompt charge recombination. Constructing porous heterojunctions is an efficient way to regulate the electron transfer path and accelerate charge migration efficiency. Herein, TiO2/defective UiO-66 porous octahedral S-scheme heterojunctions are successfully fabricated through an in-situ growth strategy. The strong interaction and charge migration behavior between TiO2 and defective UiO-66 have been studied using X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. The photocatalytic removal efficiency of tetracycline is notably improved by forming TiO2/defective UiO-66 porous heterojunctions. The promoted photocatalytic performance can be ascribed to the strong interaction between TiO2 and defective UiO-66, and the accelerated charge separation and transfer efficiency due to the formation of S-scheme heterojunctions, thus generating abundant reactive oxygen species, including O2− and OH. The optimized 38-TiO2/UiO-66-300 can eliminate 97.9 % of tetracycline in 60 min with a reaction constant rate of 0.0425 min−1, which is approximately 4 and 10 times that of pristine TiO2 and UiO-66-300, respectively. This work provides an alternate strategy for preparing highly active heterojunction photocatalysts for environmental applications.

Impact of blocking layers based on TiO2 and ZnO prepared via direct current reactive magnetron sputtering on DSSC solar cells

The optimization of dye-sensitized solar cells (DSSCs) technology towards suppressing charge recombination between the contact and the electron transport layer is a key factor in achieving high conversion efficiency and the successful commercialization of this type of product. An important aspect of the DSSC structure is the front blocking layer (BL): optimizing this component may increase the efficiency of photoelectron transfer from the dye to the semiconductor by reduction charge recombination at the TiO2/electrolyte and FTO/electrolyte interfaces. In this paper, a series of blocking layer variants, based on TiO2 and ZnO:TiO2, were obtained using the reactive magnetron sputtering method. Material composition, structure and layer thickness were referred to each process parameters. Complete DSSCs with structure FTO/BL/m-TiO2@N719/ EL-HSE/Pt/FTO were obtained on such bases. In the final results, verification of opto-electrical parameters of these cells were tested and used for the conclusions on the optimal blocking layer composition. As the conclusion, application of blocking layer consists of neat TiO2 resulted in improvement of device efficiency. It should be noted that for TiO2:ZnO/CuxO and TiO2/CuxO cells, higher efficiencies were also achieved when pure TiO2 was used as window layer. Additionally it was proven that the admixture of ZnO phase inspires Voc and FF growth, but is overall unfavorable compared to pristine TiO2 blocking layer and the reference cell, according to the final cell efficiency.

Heat Transfer and Thermal Efficiency in Oxy-Fuel Retrofit of 0.5 MW Fire Tube Gas Boiler

Industrial boilers cause significant energy wastage that could be mitigated with oxy-fuel combustion versus traditional air combustion. Despite several feasibility studies on oxy-fuel burners, they are widely avoided in industry due to major infrastructural challenges. This study measured the performance and heat transfer characteristics of each component in a 0.5 MW fire tube gas boiler after retrofitting it with an oxy-fuel burner. Comparisons were drawn across three combustion modes—air combustion, oxy-fuel combustion, and oxy-fuel flue gas recirculation (FGR). The Dittus–Boelter equation was employed to predict heat transfer in the fire tube for all combustion modes at full load (100%). Heat transfer in the latent heat section of the economizer was measured and compared with predictions using the Zukauskas equation. With this retrofit, oxy-fuel combustion improved the thermal efficiency by about 3–4%. In oxy-fuel combustion, the flow rate of exhaust gas decreased. When integrated into an existing fire tube boiler, the fire tube’s heat transfer contribution diminished greatly, suggesting the economic viability of a redesigned, reduced fire tube section. Additionally, a new design could address the notable increase in gas radiation from the fire tube in oxy-fuel and FGR, as well as aid in the efficient recovery of condensation heat from exhaust gases.

Alkyl Chains Tune Molecular Orientations to Enable Dual Passivation in Inverted Perovskite Solar Cells.

Nonradiative recombination losses occurring at the interface pose a significant obstacle to achieve high-efficiency perovskite solar cells (PSCs), particularly in inverted PSCs. Passivating surface defects using molecules with different functional groups represents one of the key strategies for enhancing PSCs efficiency. However, a lack of insight into the passivation orientation of molecules on the surface is a challenge for rational molecular design. In this study, aminothiol hydrochlorides with different alkyl chains but identical electron-donating (-SH) and electron-withdrawing (-NH3 +) groups were employed to investigate the interplay between molecular structure, orientation, and interaction on perovskite surface. The 2-Aminoethane-1-thiol hydrochloride with shorter alkyl chains exhibited a preference of parallel orientations, which facilitating stronger interactions with the surface defects through strong coordination and hydrogen bonding. The resultant perovskite films following defect passivation demonstrate reduced ion migration, inhibition of nonradiative recombination, and more n-type characteristics for efficient electron transfer. Consequently, an impressive power conversion efficiency of 25 % was achieved, maintaining 95 % of its initial efficiency after 500 hours of continuous maximum power point tracking.

Characterization of liquid-liquid two-phase flow patterns and mass transfer coefficients in Human-shaped microchannels

Based on the principle of splitting and recombining, this study designed and fabricated millimeter-scale Human-shaped microchannels. The research focused on investigating the flow patterns and mass transfer characteristics of liquid-liquid two-phase flow within the Human-shaped microchannels. The experiment utilized a water and n-butanol system to investigate the flow behavior of liquid-liquid two-phase in the channel with a flow rate ratio of 1. When the total volumetric flow rate increases from 120 µl/min to 2400 µl/min, the flow pattern experiences slug flow, slug-droplet flow, parallel flow and non-steady flow patterns respectively. The study investigated the impact of factors including total flow rate, feed method, angle, curvature, channel width, phase ration extraction efficiency and mass transfer coefficients. The Human-shaped channel exhibited superior mass transfer performance compared to conventional microchannels due to its advantageous configuration. The higher the included angle is, the stabler the flow pattern within the channel, resulting in a better mass transfer performance. Furthermore, the absence of curvature is more favorable for achieving higher mass transfer efficiency. In the experiments, the overall volume mass transfer coefficient ranged from 0.007 to 0.1742 s−1. This study can provide insights for the development and structural optimization of microchannels based on the split-recombine principle.

Three-dimensional biochar aerogel anode derived from expired yogurt for enhancing power efficiency and electron transfer at the bacteria-anode interface in microbial fuel cells

Microbial fuel cells (MFCs) are a promising and sustainable form of fuel cells that utilize electroactive microorganisms to generate electricity. However, the practical application of MFCs is limited by their low power density, inadequate biocompatibility, and suboptimal electrochemical properties. To overcome these challenges, we developed a three-dimensional high performance biochar aerogel anode (YP) made from a mixture of expired yogurt and polyvinyl alcohol (PVA) and investigated its effect on the performance of the MFC. The incorporation of PVA into the YP anodes resulted in improved electrolyte wettability and hydrophilic surfaces, thereby enhancing biocompatibility and bacterial adhesion, especially with Geobacter, reaching up to 89.6% coverage. The biofilm content reached 68.1 mg, which is 1.7 times that of carbon cloth, which improved the electron transfer efficiency at the bacteria-anode interface. Moreover, the mechanical strength of the YP anodes was increased, improving anode stability and durability. In addition, the aerogel anode exhibited impressive power density and current density values of 15.87 W m−3 and 43.76 A m−3, respectively. These values are 3.16 times and 3.60 times higher than the 5.03 W m−3 and 12.13 A m−3 of carbon cloth. This study makes a significant contribution to improving power generation in MFCs, optimizing electron transfer at the bacteria-anode interface, and paving the way for future practical applications of MFCs.

Photoelectrochemical Communication Between Cyanobacteria and Electrospun Cellulose‐Acetate–Graphene‐Based Electrodes for Photosynthetic and Respiratorial Photocurrent and Hydrogen Generations via Sustainable Solar Energy

In this article, the potential of biophotovoltaic devices (BPVs) as a sustainable solution for addressing the global energy crisis and combating climate change is explored. BPVs harness renewable electricity from sunlight and water through the photosynthetic activity of microorganisms, such as cyanobacteria and algae, serving as living photocatalysts. The focus is primarily on enhancing photocurrent outputs by developing efficient anode materials. Carbon‐based electrodes, particularly graphene (Gr), emerge as promising candidates due to their cost‐effectiveness, electrical conductivity, and mechanical strength. Despite reduced graphene oxide being commonly used, unoxidized Gr has not been extensively explored until recent research demonstrating its excellent current harvesting capacities. Additionally, 1D‐structured nanomaterials, such as electrospun nanofibers, show potential in promoting electron transport and enhancing charge collection efficiency. An innovative photoanode design is introduced, utilizing cyanobacteria immobilized on a cellulose acetate/Gr electrospun mat, offering a porous structure conducive to cyanobacterial attachment and efficient electron transfer. A complementary cathode structure, employing aniline‐modified Pt nanoparticles, facilitates the reduction of protons to yield hydrogen gas. Overall, in this study, BPVs’ potential is highlighted as a viable clean energy technology and novel approaches to enhance their efficiency and sustainability are presented.

Unraveling Interfacial Photoinduced Charge Transfer and Localization in CsPbBr3 Nanocrystals/Naphthalenediimide.

Halide perovskites have attracted much attention for energy conversion. However, efficient charge carrier generation, separation, and mobility remain the most important issues limiting the higher efficiency of solar cells. An efficient interfacial charge transfer process associated with exciton dynamics between all-inorganic CsPbBr3 nanocrystals and organic electron acceptors has been suggested. We observed a strong PL quenching of 78% in thin films when silane-functionalized naphthalenediimides (SNDI), used as electron-acceptors, are anchored on CsPbBr3 nanocrystals. Optical and structural characterizations confirm the charge transfer process without QDs degradation. The issue of whether these transferred charges are indeed available for utilization in solar cells remains uncertain. Our results reveal that the CsPbBr3 nanocrystals capped with these electron-acceptor SNDI molecules show a drastic increase in the electrical resistance and the absence of a photoconductivity effect. The results suggest charge transfer followed by strong localization of the charge carriers, preventing their extraction toward the electrodes of solar cell devices. We hope that this crucial aspect to attract attention and unveil a potential mechanism for charge delocalization, which could, in turn, lead to a groundbreaking enhancement in solar cell efficiency.

Alkyl Chains Tune Molecular Orientations to Enable Dual Passivation in Inverted Perovskite Solar Cells

Nonradiative recombination losses occurring at the interface pose a significant obstacle to achieve high‐efficiency perovskite solar cells (PSCs), particularly in inverted PSCs. Passivating surface defects using molecules with different functional groups represents one of the key strategies for enhancing PSCs efficiency. However, a lack of insight into the passivation orientation of molecules on the surface is a challenge for rational molecular design. In this study, aminothiol hydrochlorides with different alkyl chains but identical electron‐donating (‐SH) and electron‐withdrawing (‐NH3+) groups were employed to investigate the interplay between molecular structure, orientation, and interaction on perovskite surface. The 2‐Aminoethane‐1‐thiol hydrochloride with shorter alkyl chains exhibited a preference of parallel orientations, which facilitating stronger interactions with the surface defects through strong coordination and hydrogen bonding. The resultant perovskite films following defect passivation demonstrate reduced ion migration, inhibition of nonradiative recombination, and more n‐type characteristics for efficient electron transfer. Consequently, an impressive power conversion efficiency of 25% was achieved, maintaining 95% of its initial efficiency after 500 hours of continuous maximum power point tracking.

Mechanisms of partial denitrification in an integrated fixed-film activated sludge (IFAS) system: From progressive startup to stabilization

The rapid startup and long-term stability of partial denitrification (PD) processes are essential prerequisites for successful PD/Anammox systems. Bioaggregates play a significant role in impacting mass transfer efficiency and shaping the microbial community structure within the PD process. Thus, the startup and stable operation of the PD process were investigated in an integrated fixed-film activated sludge (IFAS) by inoculating activated sludge and biofilm from anoxic tanks of a wastewater treatment plant. During the initial stage of startup, a sudden increase in NO3−-N concentration induced a rapid enzyme stress response, leading to a significant increase in total NaR activity (1.38 ± 0.0 μmol·(L·min)−1 to 25.94 ± 0.23 μmol·(L·min)−1), concomitant with the inhibition of total NiR activity (13.93 ± 0.48 μmol·(L·min)−1 to 4.25 ± 0.26 μmol·(L·min)−1), thereby inducing the rapid accumulation of NO2−-N (13.39 mg·L−1) within 6 days. During the later stage of startup, enzyme stress response was subsided but the partial denitrifiers were gradually enriched, consequently leading to continuous accumulation of NO2−-N. The results of ex-situ activity showed that flocs exhibit superior PD performance in contrast to biofilm throughout the entire operational period. Meanwhile, the total extracellular polymeric substances (EPS) content and community structure in both flocs and biofilm indicated that the migration of EPS-secreted partial denitrifiers (Thauera) from flocs to biofilm was obliged by substrate deficiency during the stable operating stage (days 35–100). Therefore, the startup of PD may be sequentially mediated by two distinct mechanisms, enzyme stress response and functional bacterial enrichment, with microbial community migration occurring during the stable phase.

Surfactant-Assisted Förster Resonance Energy Transfer from a Quantum Dot Complex for Highly Stable White Light Emission.

Herein we report the fabrication of a surfactant modified quantum dot complex (S-QDC, having λem = 485 nm) nanocomposite (composed of cetyltrimethylammonium bromide surfactants and a zinc-quinolate complex attached ZnS quantum dot), the donor capability of S-QDC in Förster resonance energy transfer (FRET) with an acceptor organic molecule (λem = 573 nm), and finally their utilization in the FRET-based white light emission having features near to mid-day sunlight. The Förster distance, energy transfer efficiency, donor-acceptor distance, number of binding sites, and binding constant are evaluated to be 3.48 nm, 85.74%, 2.58 nm, 0.94, and 1.87 × 104 M-1, respectively, for the current electrostatically driven FRET pair. The solid polymer coated FRET pair composite emits white light having chromaticity color coordinates of (0.33, 0.33) and correlated color temperature of 5350 K and also shows long-term atmospheric white luminescence stability up to 30 days, photostability, and thermal stability with preservation of their pristine morphology.

Engineering design and manufacturing of a radio frequency plasma driver without Faraday shield for NBI application

A radio frequency (RF) driven ion source is favorable for high-power and long-pulse neutral beam injection (NBI) system. To reduce the damage caused by the isotropic heat and particle fluxes from the plasma, the traditional RF plasma driver of the NBI ion source introduces a Faraday shield (FS) for protection. However, the simulations and experiments show that the FS seriously affects the RF coupling and around 50 % of the input power deposits on the FS. The water-cooled discharge tubes with a double-layer ceramic structure have been developed to avoid using the FS structure. It's expected to improve the RF power transfer efficiency and to promote the development of high-power and long-pulse RF ion source. To verify the feasibility of the double-layer ceramic structure, the paper has carried out the fluid-thermal-structural coupling analysis and the fracture mechanical analysis on two proposed types: the alumina ceramic brazing structure and the silicon nitride ceramic bonding structure. The sample tests and the prototype manufacturing have been completed. Preliminary tests of the plasma discharge on the prototype of the alumina ceramic brazing structure have been launched. A plasma discharge of 30 kW and 20 s have been achieved.