Transfer Capacity Research Articles

Nano Fe3O4 improved the electron donating capacity of dissolved organic matter during sludge composting

The effect of Fe3O4 nanoparticles (Fe3O4 NPs) on the electron transfer process in aerobic composting systems remains unexplored. In this study, we compared the electron transfer characteristics of DOM in sludge composting without additives (group CK) and with the addition of 50 mg/kg Fe3O4 NPs additive (group Fe). It was demonstrated that the electron transfer capacity (ETC) and electron donating capacity (EDC) of compost-derived DOM increased by 13%–29% and 40%–47%, respectively, with the addition of Fe3O4 NPs during sludge composting. Analyzing the composition and structure of DOM revealed that Fe3O4 NPs promoted the formation of humic acid-like substances and enhanced the aromatic condensation degree of DOM. Correlation analysis indicated that the increase in EDC of DOM was closely associated with the phenolic group in DOM and influenced by quinone groups and the degree of aromatization of DOM. The higher EDC and the structural evolution of DOM in group Fe reduced the bioaccessibility of Cu, Cr, Ni, Zn. This study contributes to a deeper understanding of the redox evolutionary mechanism of DOM in sludge composting and broadens the application of iron oxides additives.

Numerical analysis of hydrothermal performance and entropy generation in an active cooling system: A case study with NEPCM, double-diffusive mixed-convection and MHD

Magnetohydrodynamic and entropy generation of double-diffusive mixed convection in a curvilinear cavity filled with nano-enhanced phase change material and a rotating cylinder has been studied in this paper. Three heat sources have been considered and a range of different variables such as Reynolds number (10 ≤ Re ≤ 100), Richardson number (0.1≤ Ri ≤ 10), Hartmann number (0≤ Ha ≤50) Lewis number (0.1≤ Le ≤ 0.9), bouncy ratio (1≤ Nz ≤ 5), fusion temperature (0.1≤ θf ≤0.9) and Stephan number (0.1≤ Ste ≤0.9). These variables have been numerically solved by applying the Finite Element Method. The main results indicated that heat transfer, mass transfer and heat capacity are hugely increased with the increase of the Re, Ri and volume concentration while decreasing with the increase of the Ha number and entropy generation. Furthermore, the melting/solidification region is hugely influenced by the fusion temperature while this variable has a negligible influence on streams, heat transfer and mass transfer. Furthermore, the value of the average Nusselt number and average Sherwood number has increased by 328 % and 258 % respectively by increasing the Reynolds number from 10 to 100. Also, these two numbers have decreased by 61 % and 54 % respectively by increasing the Hartmann number from 0 to 20.

Study on heat transfer performance of cooling channels in proton exchange membrane fuel cells based on topology optimization

Based on topology optimization method, a dual-objective function topology optimization model containing minimum average temperature and minimum flow power dissipation was established in this study. Coupled with the uneven heat generation model of proton exchange membrane fuel cells, the optimal layout scheme under the target operating conditions was adaptively obtained. The effects of volume fraction, objective function weight, and parabolic inlet velocity on the flow channel structure and cooling performance of topological cooling plates were studied. The results indicate that with the increase of volume fraction, the area of fluid region increases, the average temperature and the pressure drop of cooling plate gradually decrease. At the volume fraction of 0.5, the cooling plate has the best cooling performance. The temperature difference and maximum temperature reach the minimum values of 5.45 K and 347.58 K, respectively. When the volume fraction increases from 0.4 to 0.6, the pressure difference decreases by 67.64 %. With the increase of temperature weight coefficient, the area of high-temperature area gradually decreases, and the temperature uniformity is significantly improved. When the inlet velocity of coolant is 0.025 m/s and the temperature weight coefficient is 0.9, the average and maximum temperatures of cooling plate reach the lowest values, which are 343.53 K and 344.51 K, respectively. The maximum temperature of cooling plate under parabolic inlet velocity is of 347.87 K, which is 0.29 K higher than that under uniform inlet velocity. Non-uniform coolant inlet velocity will lead to a decrease in heat transfer capacity of cooling plate and an increase in coolant power consumption.

Molecular genetic analysis of two novel a allele to cause Ax phenotype in Chinese

BackgroundMutations of ABO gene may cause the dysfunction of ABO glycosyltransferase (GT) that can result in weak ABO phenotypes. Here, we identified two novel weak ABO subgroup alleles and explored the mechanism that caused Ax phenotype. Materials and methodsThe ABO phenotyping and genotyping were performed by serological studies and direct DNA sequencing of ABO gene. The role of the mutations was evaluated by 3D model, predicting protein structure changes, and in vitro expression assay. The total glycosyltransferase transfer capacity in supernatant of transfected cells was examined. ResultsThe results of serological showed the subject RJ23 and RJ52 both were Ax phenotypes. The novel A alleles, Avar-1 and Avar-2 were identified according to the gene analysis. Both Avar-1 and Avar-2 harbored recombinant heterozygous alleles, specifically A2.05 and O.01.02. These alleles showcased substitutions at positions c.106G > T, c.189C > T, c.220C > T, and c.1009A > G in their respective exons. It is worth noting that the crossing-over regions of these two alleles differed from each other. In vitro expression study showed that GTA mutant impaired H to A antigen conversion, and the mutant did not affect the production of GTA though the Western bolt. In silico analysis showed that GTA mutant may change the local conformation and the stability of GT. ConclusionsThe Avar-1 and Avar-2 alleles were identified, which could cause the Ax phenotype through changing the local conformation and reducing stability of the GTA.

Hybrid of non-dominated sorting genetic algorithm II and invasive weed optimization for fan duct surface heat exchanger configuration optimization design

In this research, configuration optimization was conducted for FDSHX (fan duct surface heat exchanger) that is a new type of heat exchanger adopted in aero-engine heat management in recent years. Firstly, a method of Taguchi-ANFIS (Taguchi-Adaptive Neuro-Fuzzy Inference System), which can reduce training data volume utilizing orthogonal experimental matrix, was proposed to construct a rapid response mathematical model between three configuration parameters, including fin pitch, fin thickness, and oil passages number, and two design indicators, including heat transfer capacity and operating weight, based on the data prepared by an experimental validated FDSHX heat transfer capacity calculation method using heat transfer unit simulation. Secondly, a hybrid method of NSGA II-IWO (Non-dominated Sorting Genetic Algorithm II-Invasive Weed Optimization), which can simultaneously obtain the strong abilities of exploration and escaping from trap into local optima, was proposed to drive the constructed response mathematical model to enhance heat transfer through adjusting the three configuration parameters. Optimization comparison was performed between NSGA II-IWO and four classic optimization algorithms including GA (Genetic Algorithm), IWO (Invasive Weed Optimization), CA (Cultural Algorithm), and HS (Harmony Search). This research provides an integrated solution to help mechanical engineers improve the applicability and reasonableness of FDSHX design.

Molecular Epidemiology of mcr-1-Positive Polymyxin B-Resistant Escherichia coli Producing Extended-Spectrum β-Lactamase (ESBL) in a Tertiary Hospital in Shandong, China.

Escherichia coli, a rod-shaped Gram-negative bacterium, is a significant causative agent of severe clinical bacterial infections. This study aimed to analyze the epidemiology of extended-spectrum β-lactamase (ESBL)-producing mcr-1 -positive E. coli in Shandong, China. We collected 668 non-duplicate ESBL-producing E. coli strains from clinical samples at Shandong Provincial Hospital between January and December 2018, and estimated their minimum inhibitory concentrations (MICs) using a VITEK® 2 compact system and broth microdilution. Next-generation sequencing and bioinformatic analyses identified the mcr-1 gene and other resistance genes in the polymyxin B-resistant strains. The conjugation experiment assessed the horizontal transfer capacity of the mcr-1 gene. Of the strains collected, 24 polymyxin B-resistant strains were isolated with a positivity rate of 3.59% and among the 668 strains, 19 clinical strains carried the mobile colistin resistance gene mcr-1, with a positivity rate of approximately 2.8%. All 19 clinical strains were resistant to ampicillin, cefazolin, ceftriaxone, ciprofloxacin, levofloxacin, and polymyxin B. Seventeen strains successfully transferred the mcr-1 gene into E. coli J53. All transconjugants were resistant to polymyxin B, and carried the drug resistance gene mcr-1. The 19 clinical strains had 14 sequence types (STs), with ST155 (n = 4) being the most common. The whole-genome sequencing results of pECO-POL-29_mcr1 revealed that no ISApl1 insertion sequences were found on either side of the mcr-1 gene. Our study uncovered the molecular epidemiology of mcr-1-carrying ESBL-producing E. coli in the region and suggested horizontal transmission mediated by plasmids as the main mode of mcr-1 transmission.

Experimental and numerical study on the flow and heat transfer of ring-ribbed tank in deep-sea manned submersible

The ring-ribbed tank is the key equipment of cooling system of deep-sea manned submersible. The heat transfer characteristics of the outer wall and the heat transfer and flow characteristics of the inner flow channel of the ring-ribbed tank for different inlet and outlet temperatures and flow rates were studied through a water tank test. The results indicate that Nusselt number for the inner flow channel correlates with Reynolds and Prandtl numbers, while for the outer wall, it correlates with Grashof and Prandtl numbers with an overall error within 5%. A numerical study using the Realizable k-ε turbulence model and Boussinesq approximation of the flow-solid conjugate heat transfer is conducted, which can accurately determine the heat exchange capacity and the import and export differential pressure with an average relative error of 1.98% for hot water temperature and 7.73% for shell wall temperature. Additional simulations for determining the heat transfer capacity and flow resistance characteristics of the ring-ribbed tank in open water results demonstrate that the differential pressure and its coefficient are basically consistent with model test results. The cooling system can achieve a heat transfer rate of up to 17 kW with an external seawater flow velocity of approximately 2 knots.

Preparation of a surface molecularly imprinted thermo-sensitive polymer for selective trypsin capture

Molecularly imprinted polymers (MIPs) are innovative porous materials created through polymerization templating methods for highly selective, sensitive detection and separation of the desired chemical species, known as template molecules. Surface imprinting over nano-sized substrates with special functional groups is an effective approach for improving the mass transfer and rebinding capacity. In this study, we successfully performed surface imprinting using methacrylic acid (MAA) and thermoresponsive N-isopropyl acrylamide (NIPAm) as functional monomers on acrylic-functionalized silica nanoparticles and served as a Trypsin artificial receptor. The resulting Trypsin imprinted polymer exhibited a binding capacity of 1022.44 mg/g, surpassing the non-imprinted polymer’s capacity of 292.41 mg/g within 45 min. Moreover, the imprinting factor, the main influence factor in MIP performance, was 3.5, demonstrating the significant selectivity of the polymeric products. In addition, due to the temperature sensitivity of NIPAm the template removing process was simply done by changing pore size. The silica nanoparticles and the synthesized MIP particles had diameters of approximately 95 nm and 105 nm, respectively, with the polymer layer thickness being around 5 nm. The MIP adsorption model followed the Freundlich isotherm and pseudo-second-order kinetics resulting in efficiencies of 93.0 % and 95.4 %, respectively. The developed Trypsin imprinted polymer was reusable for four consecutive uses,demonstrating both resilience and selectivity towards Trypsin.

Numerical investigation of MHD mixed convection in an octagonal heat exchanger containing hybrid nanofluid

Nowadays, the advancement of heat transmission for the heat exchanger device is an important field of research for many researchers. In this work, a numerical study has been conducted to investigate the thermal performance of a mixed convective flow through the octagonal heat exchanger covered by hybrid nanofluid (Cu-TiO2-H2O). A magnetic field has been introduced inside the cavity to investigate the mixed convective hydrodynamics heat flow characteristics. The nanofluid cores absorb/release energy to manage heat transmission by increasing or decreasing inside the cavity domain as the host fluid and dispersed hybrid nanofluid circulate within the cavity. After transforming the governing equations into a generalized, non-dimensional formulation, the finite element approach is utilized to solve the associated equations. Additionally, response surface methodology is also applied to test the responses of the associated factors. Heat transport was examined in relation to the effects of nanofluids fusion temperature, boundary wall properties, Reynolds number, Hartmann number and nanoparticle volume fractions. The outcomes of this study are analysed by measuring streamline profiles, isotherms, average Nusselt number, velocity profile, and 2D and 3D response surfaces of the computational domain. The underlying flow controlling parameters for instance Reynolds number (10 ≤ Re ≤ 200), Hartmann number (0 ≤ Ha ≤100), and nanoparticle volume fractions (0 ≤ ϕ ≤ 0.1), the influences have been considered. The findings also reveal that the thermal performance is being boosted due to augmentation of Re and ϕ, but reverse behavior is noticed for Ha. Furthermore, the response surfaces obtained from response surfaces methodology express that the Re and ϕ have shown positive influence, and Ha has shown negative influence on Nuav. Utilizing a hybrid nanofluid of Cu-TiO2-H2O increases the heat transfer capacity of water to 25.75 %. Moreover, the findings could guide to design of a mixed convective heat exchanger for industrial purposes.

Investigation on the heat transfer characteristics of rotor-stator cavity with different disk roughness

In this study, we numerically investigated the rotor-stator cavity for different disk surface roughness (rough rotor-RR, rough stator-RS, and rough rotor & stator-RRS) with the aim of determining the effect of surface roughness on the heat transfer characteristics of the disk cavity over a range of parameters. First, we experimentally verified that the numerical simulation has high accuracy. Next, the third-generation vortex identification method-Ω vortex identification method is used to preliminarily analyze the effect of different disk cavity roughness on the heat transfer in the rotor-stator cavity. The results indicate that the roughness of the rotor surface plays a dominant role in influencing the flow in the disk cavity. Third, we qualitatively and quantitatively analyzed the temperature field in the disk cavity. Interestingly, we discovered that the roughness of the stator decreases the temperature in the disk cavity to some extent. Thus, we judged the effect of stator surface roughness on the flow in the disk cavity based on the pressure variation in the rotor-stator cavity and gave an optimal roughness range for the stator. This will help to improve the cooling effect in the disk cavity. Finally, we investigated the effect of roughness on the rotor-stator heat transfer capacity. The effect of roughness on overall heat transfer in disc cavities is quantified based on average local heat transfer coefficient. It was concluded that the local heat transfer coefficient of the disk cavity is sensitive to the wall roughness, even for small wall roughness. We then added a roughness term to our previous work on average Nusselt number predictions for disk cavities. This provides a more accurate prediction of the heat transfer capacity of the disk cavity. On the basis of our results, it can provide some assistance to the relevant designers to quickly and accurately predict the heat transfer capacity of the rotor-stator cavity.

Catalytic ozonation performance and mechanisms of Cu-Co/γ-Al2O3 to achieve antibiotics and ammonia simultaneously removal in aquaculture wastewater

Antibiotics and ammonia are generally co-existed in aquaculture tailwater; moreover, ammonia would also be produced from during ozonation, and should be simultaneously removed before discharge or reuse. In this study, catalyst Cu-Co/γ-Al2O3 was screened from a variety of metal oxides and applied in catalytic ozonation of three kinds of antibiotics and NH+4-N. Factors that affected their removal, including catalyst dosages, O3 concentration, initial pH as well as co-existing ions, were investigated. Moreover, the mechanisms were probed by exploring free radicals’ role as well as intermediates identification; and the characteristics of catalysts before and after use were evaluated using SEM, EDS, XRD, XPS, and BET. Results demonstrated that Cu-Co/γ-Al2O3 could significantly stimulate the degradation of the selected antibiotics and NH+4-N during ozonation. The degradation efficiencies of ciprofloxacin (CIP), tetracycline (TC), sulfamethoxazole (SMX) and NH+4-N can reach up to 95.0 %, 100.0 %, 96.2 %, and 75.7 %, respectively. Plenty of oxygen vacancy (Ovs) and sufficient alkaline sites on the surface of catalyst facilitated the adsorption of pollutants. Furthermore, the transformation of metal ions Cu+/Cu2+ and Co2+/Co3+ enhanced the electron transfer capacity and favored the formation of reactive oxygen species (ROS) during catalytic ozonation reaction, and their roles in catalytic ozonation has also been verified. The radical quenching experiments demonstrated that ·OH was the main contributor for enhancing pollutants removal. The results of Gaussian calculation coincided with those intermediates detected by UPLC-Q-TOF-MS, the pollutants’ removal mechanisms by catalytic ozonation were proposed basing on them. The overall toxicities were compared for ozone only/catalytic ozonation by zebrafish embryo experiment. The results of this study would provide new a feasible way for treating antibiotics and NH+4-N simultaneously in aquaculture wastewater.

Effect of ball milling activation on CO2 mineralization performance in fly ash and fire resistance capabilities of mineralized product

Coal-fired power generation has always been a major energy supply source globally. However, a large amount of CO2 is emitted with the combustion of coal resources, and fly ash, a by-product of coal combustion, is also accumulated in large quantities. The application of CO2 mineralization in fly ash can not only reduce CO2 emission but also effectively manage industrial waste, thereby promoting environmental sustainability. This paper used the mechanical ball milling method to activate fly ash and investigated the effects of ball milling time and speed on the CO2 sequestration in fly ash. At 30 min ball milling time and 400 r/min ball milling speed, the modified fly ash achieves a good CO2 sequestration capacity of 81.70 gCO2/kgFA. Compared with raw fly ash, the CO2 consumption of treated fly ash is higher at 75.41 mmol/mL. The specific surface area and pore volume of treated fly ash are larger at 1.57 m2/g and 4.33 cm3/kg respectively, which is beneficial for enhancing mass transfer capacity and the carbonation effect. As the ratio of mineralized product/coal increases from 0.5 to 4, the crossing-point temperature increases from 157.20 °C to 165.15 °C. Based on the experimental results, the paper discussed the mechanism of ball milling activation to enhance the carbonation effect of fly ash. This study provides theoretical references for the environmentally friendly utilization of fly ash.

Decoding the Biomimetic Mineralization of Metal-Organic Frameworks in Water.

This study unveils the "green" metal-organic framework (MOF) structuring mechanism by decoding proton transfer in water during ZIF-8 synthesis. Combining in situ small- to wide-angle X-ray scattering, multiscale simulations, and quantum calculations, we reveal that the ZIF-8 early-stage nucleation and crystallization process in aqueous solution unfolds in three distinct stages. In stage I, imidazole ligands replace water in zinc-water cages, triggering an "acidity flip" that promotes proton transfer. This leads to the assembly of structures from single zinc ions to 3D amorphous cluster nuclei. In stage II, amorphous nuclei undergo a critical transformation, evolving into crystalline nuclei and subsequently forming mesoscale-ordered structures and crystallites. The process proceeds until the amorphous precursors are completely consumed, with the transformation kinetics governed by an energy barrier that determines the rate-limiting step. In stage III, stable crystallite nanoparticles form in solution, characterized by a temperature-dependent thermal equilibrium of molecular interactions at the crystal-solution interface. Beyond these core advancements, we explore the influence of encapsulated pepsin and nonencapsulated lysozyme on ZIF-8 formation, finding that their amino acid proton transfer capacity and concentration influence the resulting biomolecule-MOF composite's shape and encapsulation efficiency. The findings contribute to understanding the molecular mechanisms behind biomimetic mineralization and have potential implications for engineering proteins within amorphous MOF nuclei as protein embryo growth sites.

Strongly Coupled NiMo@Alloy‐LDH Interfaces with Low‐Barrier Schottky Junctions for Oxygen Evolution Reaction

AbstractThe main challenge in developing Schottky‐contact OER catalytic devices based on layered double hydroxides (LDHs) is to achieve metal–semiconductor junctions with low contact resistance and high charge transfer capacity. However, due to the presence of high potential barriers and Fermi pinning, conventional Schottky contacts are usually unsatisfactory, resulting in poor‐working electrode performance and high energy consumption. In this study, a new concept of “hindrance factor” is introduced to quantify the difficulty of electron transfer, and a low‐hindrance factor Schottky contact formed by strong coupling of semiconductor LDH and NiMo alloy clusters is designed. This interface guides charge redistribution, optimizes the bonding and orbital states of adsorption sites, and enhances the targeted adsorption of OH intermediates. The results show that the configured NiMo@NiFeCe‐LDH working electrode only needs 1.445 V (vs RHE) to drive the reaction and shows excellent durability in 400 h of testing. At the same time, based on this study, a strategy for screening high‐performance Schottky junctions is developed. This strategy provides a bridge for studying interface properties, orbital hybridization, and charge transfer, reveals the potential mechanism for reducing contact resistance, and has important guiding significance for screening high‐performance metal–semiconductor electrocatalysts and stability.

Experimental and numerical investigation of flow and heat transfer characteristics of teardrop and circular pin fins in a wedge channel

ABSTRACT Pin fin arrays, which have a high heat transfer capacity and minimal pressure loss, are currently being used as the primary cooling technique for the turbine trailing edge cooling channel used in modern gas turbines. To enhance the heat transmission efficiency of the channel, this study proposes the use of a circular-shaped pin and a teardrop pin, through both experimental and numerical investigations. The numerical simulations conducted in the Reynolds number range of 10,000 to 80,000 are used to investigate and compare the flow and heat transfer parameters of a wedge channel which has three rows of staggered circular-shaped and teardrop-shaped pin fins with a diameter of 12 mm. The experiment showed that teardrop pin fns with staggered arrangement has different effect on flow pattern and heat transfer characteristics. Heat transfer is increased by 10.45% when compared to the circular pin fins and the pressure drop of teardrop pin fins is reduced by 54.6%.Therefore thermal performance factor exhibits a 25.4% increase when compared to circular fins.

Intrinsic and Extrinsic Factors Associated with Hair Graying (Canities) and Therapeutic Potential of Plant Extracts and Phytochemicals

This review aims to gain insight into the major causes of hair graying (canities) and how plant-derived extracts and phytochemicals could alleviate this symptom. Research articles on human hair graying were searched and selected using the PubMed, Web of Science, and Google Scholar databases. We first examined the intrinsic and extrinsic factors associated with hair graying, such as the reduced capacity of melanin synthesis and transfer, exhaustion of melanocyte stem cells (MSCs) and melanocytes, genetics and epigenetics, race, gender, family history, aging, oxidative stress, stress hormones, systematic disorders, nutrition, smoking, alcohol consumption, lifestyle, medications, and environmental factors. We also examined various plants and phytochemicals that have shown a potential to interfere with the onset or progression of human hair graying at different levels from in vitro studies to clinical studies: the extract of Polygonum multiflorum and its major components, 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside and emodin; the extract of Eriodictyon angustifolium and its major flavonoid compounds, hydroxygenkwanin, sterubin, and luteolin; the extracts of Adzuki beans (Vigna angularis), Fuzhuan brick tea (Camellia sinensis), and Gynostemma pentaphyllum; bixin, a carotenoid compound found in Bixa orellana; and rhynchophylline, an alkaloid compound found in certain Uncaria species. Experimental evidence supports the notion that certain plant extracts and phytochemicals could alleviate hair graying by enhancing MSC maintenance or melanocyte function, reducing oxidative stress due to physiological and environmental influences, and managing the secretion and action of stress hormones to an appropriate level. It is suggested that hair graying may be reversible through the following tactical approaches: selective targeting of the p38 mitogen-activated protein kinase (MAPK)–microphthalmia-associated transcription factor (MITF) axis, nuclear factor erythroid 2-related factor 2 (NRF2), or the norepinephrine–β2 adrenergic receptor (β2AR)–protein kinase A (PKA) signaling pathway.

Electrohydrodynamic characteristics in parallel-fin channels and enhanced heat transfer performance of an ionic wind heat sink

High heat flux density may lead to a decline in the performance of highly integrated electronic components, which presents a major challenge to thermal management strategies. This work developed ionic wind heat sinks with parallel-fin channels for cooling high-power chips. The study examined the effects of intake air velocity, number of electrodes, and discharge spacing on the distribution of ionic wind flow and the improved heat transfer performance of the ionic wind heat sink. The findings suggest that the ionic wind heat sink with wire electrodes perpendicular to the fin channels can withstand higher operating voltages and generate more reliable corona discharges. The improved heat transfer capabilities are achieved with reduced inlet air velocity. The heat transfer enhancement factor (HTEF) of the ionic wind heat sink decreases as the discharge spacing increases, leading to a reduction in the peak value of the body force. The heat transfer capacity declines as the number of wire electrodes increases, because marginal effects lessen disruption to the thermal boundary layer. An effective airflow is achieved when wire electrodes are positioned upstream of the heat sink and run parallel to the fins, ensuring a steady and efficient cooling process. The design effectively disrupts the thermal boundary layer, reducing momentum loss in the flow and increasing the HTEF value by 21.2%. This improvement significantly enhances the heat dissipation capacity. The structurally optimized heat sink demonstrates excellent overall performance and is a viable option for improving heat dissipation in electronic devices.

Enhancing the production of reactive oxygen species in the rhizosphere to promote contaminants degradation in sediments by electrically strengthening microbial extracellular electron transfer

The production of reactive oxygen species (ROS) in the rhizosphere is limited by the low extracellular electron transfer capacity of indigenous microorganisms. In the present study, electrical stimulation was used to promote the generation of rhizospheric ROS by accelerating extracellular electron transfer. The result showed that •OH concentrations in the electrically stimulated group (ES group) exceeded the control group by 15.76 %. Accordingly, the removal rate of the target pollutant (i.e., 2,4-dichlorophenol, and sulfamethoxazole) was 20.01 %−24.80 % higher in the ES group than in the control group. The sediment of the ES group had a higher capacity (30.55 %) and a lower electrical resistance (29.15 %) compared to the control group, which subsequently promoted the dissimilatory iron reduction to produce Fe(II) for triggering a Fenton-like process. The increased extracellular respiratory capacity under electrical stimulation could be attributed to the polarization of C-N and CO bonds, which provided more electron storage sites and thus participated in proton-coupled electron transfer. In addition, the concentration of ATP and co-enzymes (NADH/NAD+ and Complex I/Complex III), reflecting electron exchange within respiratory chains, increased distinctly under electrical stimulation. Applying electrical stimulation seemed feasible to increase ROS production and contaminant degradation in the rhizosphere, deepening the understanding of electrical stimulation to promote the production of ROS in the natural system.

Enhanced activation of peroxymonosulfate with cobalt-doped manganese-iron oxides for contaminant degradation: Regulation of oxygen vacancy defects

Peroxymonosulfate (PMS) based on heterogeneous catalytic reaction was a promising advanced oxidation process (AOP) to remove refractory contaminants. However, the contaminant degradation efficiency was challenged by the limited number of catalytic active site and low capacity for durable electron transfer. In this study, cobalt-doped manganese-iron oxides (CoxMn1-xFe2O4) rich in oxygen vacancy (Ov) were synthesized using a microwaved hydrothermal method and applied to activate PMS for bisphenol A (BPA) degradation, which achieved the complete removal of BPA within 30 min. In all samples, Co0.5Mn0.5Fe2O4 exhibited good catalytic activity for PMS, which was approximately 21.10 times higher than that of MnFe2O4. The results of density functional theory calculations and in-situ characterization demonstrated that the enhanced performance was ascribed to the generation of Ov and the enrichment of active site, which significantly accelerated the cycling of redox pairs and improved the PMS adsorption, which was more favorable to the formation of active specie in the electron transport process. The oxidation process involved both free radical and non-radical mechanisms, with main reactive species of O2−, and 1O2 being responsible for BPA degradation. In addition, the effects of different aqueous matrices, the results of reusability experiments, and ecotoxicity assessment experiments demonstrated the viability of the Co0.5Mn0.5Fe2O4/PMS system for real sewage purification. This research revealed a structural regulation method to enhance the catalytic activity of the material and offered new perspectives on the engineering of rich Ov.

Functionalized ZnFe2O4@Mesoporous silica nano-support for lipase enzyme immobilization: Enhanced biocatalysis and antibacterial activity for food industry applications

Enzymes, as highly efficient biocatalysts, play a crucial role in diverse biotechnological applications. However, enzyme (re)purification and recovery challenges pose substantial obstacles, rendering them costly for industrial utilization. Addressing this, our study developed mesoporous zinc ferrite nanoparticles coated with amine-functionalized mesoporous silica structure (ZnFe2O4@MS) through the solvothermal method. These nanoparticles are an effective nano-support for immobilizing Candida rugosa Lipase (CRL), ensuring easy separability and recoverability through a magnetic field and providing a significant surface area for high mass transference capacity. Immobilizing the lipase on the nano-support (ZnFe2O4@MS/CRL) through covalent bonds on the surface and within the pores led to a notable increase in enzyme activity from 324 U/mg for free enzyme to 689 U/mg for immobilized enzyme. This indicates unchanged active sites post-immobilization, accompanied by enhanced catalytic activity. The immobilized lipases demonstrated prolonged stability at elevated temperatures, maintaining over 59% of initial catalytic activity through five cycles. Furthermore, ZnFe2O4@MS/CRL exhibited substantial antibacterial activity against Staphylococcus aureus, more than that observed in Gram-negative bacteria. The immobilized lipase was also effective in synthesizing banana flavor (isoamyl acetate) in n-hexane, achieving 64% esterification at 45 °C after 4 h. Overall, the study underscores the industrial promise of this immobilized enzyme system, emphasizing its potential for sustainable and cost-effective biotechnological processes.