Effects Of Key Factors Research Articles

Activation mechanism of CoFe2O4 nanocatalysts on different oxidants and degradation efficiency of butyl xanthate

Owing to the technological limitations associated with beneficiation technology, large amounts of flotation reagents remain in mineral processing wastewater, which is extremely detrimental to humans and the environment. In addition, direct reuse of mineral processing wastewater will adversely affect the entire mine water system. Efficient treatment of residual butyl xanthate from tailing wastewater has recently attracted increasing interest. In this study, we compared the degradation efficiencies of cobalt iron oxide (CoFe2O4) nanoparticles assisted by sulfite-activated advanced processes and persulfate (PDS) and peroxymonosulfate (PMS) advanced oxidation processes on butyl xanthate (BX) for the first time and explored possible reaction mechanisms in various systems. We conducted comprehensive experiments on the acid/alkali washed catalysts using oxidizing agents, obtaining catalysts best adapted to three degradation systems. Results of batch experiments indicated that the BX degradation rate for all the three systems exceeded 95 % within 60 min under their respective optimal conditions and that the best total organic carbon content (TOC) removal rate for these systems was 85.79 %. The effects of key factors, such as catalyst dosage, oxidant dosage, solution pH, and coexisting ions, on BX degradation were investigated. Furthermore, the active free radicals that played a major role in each system were detected via electron paramagnetic resonance (EPR). EPR results indicated that SO3·− and ·O2− were the main active species of the CoFe2O4/sodium sulfite system, ·OH and ·O2− participated in the degradation of BX in the CoFe2O4/PDS system, and ·O2− was present in the CoFe2O4/PMS system. Thus, this study promotes the application of CoFe2O4 with magnetism as a catalyst in wastewater treatment and provides new insights into the effective treatment of organic pollutants in tailing wastewater.

Transcriptomic and proteomic investigations identify PI3K-akt pathway targets for hyperthyroidism management in rats via polar iridoids from radix Scrophularia

High-polarity iridoids from Radix Scrophulariae (R. Scrophulariae) offer a range of benefits, including anti-inflammatory, antioxidant, antitumour, antibacterial, antiviral, and antiallergic effects. Although previous studies have indicated the potential of R. Scrophulariae for hyperthyroidism prevention and treatment, the specific active compounds involved and their mechanisms of action are not fully understood. This study explored the effects of high-polarity iridoid glycosides from R. Scrophulariae on hyperthyroidism induced in rats by levothyroxine sodium. The experimental design included a control group, a hyperthyroidism model group, and a group treated with iridoid glycosides. Serum triiodothyronine (T3) and thyroxine (T4) levels were quantified using an enzyme-linked immunosorbent assay (ELISA). Transcriptomic and proteomic analyses were applied to liver samples to identify differentially expressed genes and proteins. These analyses were complemented by trend analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The effectiveness of key factors was further examined through molecular biology techniques. ELISA results indicated a notable increase in T3 and T4 in the hyperthyroid rats, which was significantly mitigated by treatment with iridoid glycosides. Transcriptomic analysis revealed 6 upregulated and 6 downregulated genes in the model group, showing marked improvement following treatment. Proteomic analysis revealed changes in 30 upregulated and 50 downregulated proteins, with improvements observed upon treatment. The PI3K-Akt signalling pathway was investigated through KEGG enrichment analysis. Molecular biology methods verified the upregulation of Spp1, Thbs1, PI3K, and Akt in the model group, which was reversed in the treatment group. This study revealed that highly polar iridoids from R. Scrophulariae can modulate the Spp1 gene and Thbs1 protein via the PI3K-Akt signalling pathway, suggesting a therapeutic benefit for hyperthyroidism and providing a basis for drug development targeting this condition.

Upcrossing‐based time‐dependent resilience of aging structures

The time-dependent resilience of an in-service aging structure provides quantitative measure of the structural ability to prepare for, adapt to, withstand and recover from disruptive events. Resilience models have been proposed in the literature to evaluate the resilience of aging structures subjected to discrete load processes, which are, however, not applicable to handle resilience problems considering continuous load processes. In this paper, a new method is developed to evaluate the time-dependent resilience of aging structures subjected to a continuous load process. The proposed method serves as the complement of the existing resilience models addressing discrete load processes, and takes into account the aging effects of the structural resistance/capacity and the nonstationarity in loads as a result of climate change. A structure suffers from a damage state upon the occurrence of an upcrossing of the load effect with respect to the resistance/capacity, leading to the reduction of the performance function, followed by a recovery process that restores the performance. The proposed method enables the time-dependent resilience to be evaluated via a closed form solution. It is also revealed that, the proposed resilience model takes an extended form of the existing formula for upcrossing-based time-dependent reliability, thus establishing a unified framework for the two quantities. The applicability of the proposed method is demonstrated through examining the time-dependent resilience of a residential building subjected to wind load. The effects of key factors on resilience, including the nonstationarity and correlation structure of the load process, as well as the resistance/capacity deterioration scenario, are investigated through an example. In particular, the structural resilience would be overestimated if ignoring the potential impacts of climate change, which is a relatively non-conservative evaluation.

Enhancing the performance of alumina-pillared clay for phenol removal from water solutions and polyphenol removal from olive mill wastewater: Characterization, kinetics, adsorption performance, and mechanism

An alumina-pillared clay (Al-PILC) has been synthesized and tested for its ability to adsorb phenol from aqueous solutions, and polyphenols from Olive Mill Wastewater (OMW). The synthesis processes were investigated by varying parameters like the Al/clay ratio, with a molar ratio of [OH−]/[Al3+] = 2.4. Various techniques, including XRD, BET, XRF, FTIR, and SEM were used to characterize the resulting solids. The effect of key factors as pH, initial pollutant concentration, and contact time, were examined in order to evaluate the phenol adsorption capacities of raw clay (RC) and optimized Al-PILC10 materials. The specific surface areas of RC and Al-PILC10 were 40 and 127 m2/g, respectively, resulting in increasing the phenol adsorbed quantity from 14.15 mg/g for RC to 30.61 mg/g for Al-PILC10 clays, at pH 2 and 45 °C. Pseudo-second-order kinetics and Freundlich adsorption isotherm were suitable for describing phenol adsorption on both clays. Furthermore, Al-PILC10 exhibits an impressive removal efficiency of 76 % for polyphenols from OMW, in contrast to the 50 % achieved by RC at acidic pH. Furthermore, Al-PILC10 showcased a superior desorption rate and a favorable regeneration capacity of 64 % compared to RC (45 %), even after multiple adsorption-desorption cycles. These findings emphasize the potential of pillared clay as a cost-effective adsorbent for the efficient removal of phenol and polyphenols from wastewater.

Deciphering spatial heterogeneity of maritime accidents considering impact scale variations

ABSTRACT Ensuring maritime safety has ascended as a preeminent concern within the global maritime sector. Understanding how factors affect maritime accidents’ consequences in different water areas would be of great benefit to preventing the occurrence or reducing the consequences. This study thus employed a multi-scale geographically weighted regression (MGWR) model on the accident dataset from Fujian waters in the East China Sea, to quantify the influences of different factors as well as the spatial heterogeneity in the effects of key factors on maritime accident consequence. The performances of MGWR are compared with multiple linear regression (MLR) and GWR. As expected, MGWR outperforms the other two models in terms of its ability to clearly capture the unobserved spatial heterogeneity in the effects of factors. Results reveal notably distinct influences of some factors on maritime accident consequences in different locations. An intuitive indication by MGWR is that approximately 50% of the accidents present positive coefficients of good visibility while other locations are negative, which are failed to recognize by MLR. The outcomes provide insights for making appropriate safety countermeasures and policies customized for different water areas.

Numerical Evaluation of Commingled Production Potential of Marine Multilayered Gas Hydrate Reservoirs Using Fractured Horizontal Wells and Thermal Fluid Injection

Multilayered reservoirs with coexisting free gas and hydrates are primary targets for commercialization, nevertheless, the extremely low permeability greatly limits their extraction efficiency. Herein, multilayer commingled production using horizontal wells stimulated by hydraulic fracturing and thermal fluid injection was proposed to enhance productivity, and the effects of key factors on co-production performance were numerically examined, with the reservoir located in the Shenhu Area as the geological background. The results indicated that due to severe interlayer contradictions, the stimulation capabilities of using fracturing or thermal fluid injection alone were limited, in particular, the extraction of hydrates severely lagged behind. However, their combination exhibited tantalizing productivity due to strengthened inter-well interaction. Reducing the fracture spacing was more effective than increasing fracture conductivity in shortening the production cycle, and intensive fractures with adequate flow capacity were suggested for gas enhancement and water control. When the fracture spacing was reduced from 30 to 5 m and the fracture conductivity increased from 10 to 100 D·cm, the horizontal section length for commercial production (average daily gas production of 50,000 m3 and recovery ratio of 0.7) was reduced from 1758 to 146 m, which is lower than the on-site horizontal section length of 250–300 m. Therefore, the proposed development mode is promising for the commingled production of gas and hydrates.

Charging characteristics of long distance accumulator for underwater electro-hydraulic control system.

Long distance accumulators are widely used in underwater electro-hydraulic control systems. However, as the working depth increases, the underwater umbilical cable becomes longer. The actual physical properties of the gas in the accumulator change. These factors affect the charging characteristics of the accumulator. To address the above issues, a simulation model of the charging of the long distance accumulator under real operating conditions is developed. Among them, the real properties of the gas inside the accumulator were calculated using the Redlich-Kwong-Soave method. The coefficient of friction within the umbilical cable is based on the Reynolds number and relative roughness. The simulation data were compared with the experimental results in the South China Sea to verify the accuracy of the simulation model. The effects of key factors on the charging characteristics of the long distance accumulators were also analyzed. The results show that the simulation results are in good agreement with the experimental results. The law of accumulator charging was analyzed: the greater the pressure of the gas source, the smaller the accumulator charging time; the greater the working water depth, the shorter the accumulator charging time. The research provides guidance for the design of long distance accumulators.

Design of a wideband and tunable radar absorber

To effectively address the challenges posed by intricate and dynamic electromagnetic environments, we propose a wideband and tunable radar absorber in this paper. The proposed absorber, composed of graphene capacitor, plasma enclosed within a sealed glass cavity, radar absorbing material (RAM), FR-4 and copper plate, allows for tunable radar absorbing performance through the manipulation of the electromagnetic properties of the graphene capacitor and plasma. Based on the equivalent circuit model, the reflectivity of the radar absorber is analyzed using transmission line theory (TLT). Good agreement is observed between the full-wave simulations and the TLT. The study thoroughly investigates the influence of graphene, plasma, and RAM components, as well as their sequential arrangement within the radar absorber, on its reflectivity, expounding the fundamental mechanism of these materials’ synergistic integration. Additionally, the effects of key factors, including the surface resistance R g of graphene, plasma frequency collision frequency and plasma thickness on the radar absorbing performance are examined. Our findings reveal that adjusting surface resistance R g controls the absorbing amplitude, and manipulation of the plasma frequency and collision frequency tunes the absorbing frequency and effective absorbing band. By appropriately adjusting the surface resistance R g of graphene, plasma frequency and collision frequency the proposed radar absorber exhibits superior performance in the frequency range of 1 GHz to 10 GHz. The radar absorber we propose serves as a significant reference for the application of tunable radar absorbers and adaptive radar stealth techniques.

A critical review of enzymes immobilized on chitosan composites: characterization and applications.

Enzymes with industrial significance are typically used in biological processes. However, instability, high sensitivity, and impractical recovery are the major drawbacks of enzymes in practical applications. In recent years, the immobilization technology has attracted wide attention to overcoming these restrictions and improving the efficiency of enzyme applications. Chitosan (CS) is a unique functional substance with biocompatibility, biodegradability, non-toxicity, and antibacterial properties. Chitosan composites are anticipated to be widely used in the near future for a variety of purposes, including as supports for enzyme immobilization, because of their advantages. Therefor this review explores the effects of the chitosan's structure, molecular weight, degree of deacetylation on the enzyme immobilized, effect of key factors, and the enzymes immobilized on chitosan based composites for numerous applications, including the fields of biosensor, biomedical science, food industry, environmental protection, and industrial production. Moreover, this study carefully investigates the advantages and disadvantages of using these composites as well as their potential in the future.

Thermal performance of the aquifer thermal energy storage system considering vertical heat losses through aquitards

The aquifer thermal energy storage (ATES) system is an efficient method to overcome the gap between energy supply and demand over time and space. Heat storage and preservation abilities are key issues of a successful ATES project. However, most of previous studies only focus on heat storage and recovery abilities of the ATES, while the heat preservation ability of aquitards is neglected. Besides, effects of key factors on heat losses into aquitards still remain unclear, which makes appropriately selecting reservoirs for the heat storage challenging. Thus, the heat loss efficiency is defined to represent the heat preservation ability of aquitards, through which ATES thermal performances are comprehensively evaluated. Effects of key factors on thermal performances are analyzed and optimal reservoirs for the heat storage are recommended. Results indicated that key factors had different impacts on heat losses and thermal recovery. The conduction was the major loss mode and was sensitively affected by aquitard parameters. An aquifer with a lower thermal conductivity, a higher porosity and a superior heat capacity was more suitable for the heat storage. The aquitard with lower porosity, thermal conductivity and heat capacity was better. On the premise of sealing, increasing the aquitard permeability was conducive.

Performance Study of Generalized Space Time Block Coded Enhanced Fully Optical Generalized Spatial Modulation System Based on Málaga Distribution Model

This paper proposes a generalized space time block coded (GSTBC) enhanced fully optical generalized spatial modulation (EFOGSM) system based on Málaga (M) turbulent channel. GSTBC-EFOGSM adopts the hybrid concept of generalized space time block coded and optical spatial modulation to further utilize the high transmission rate of EFOGSM and the diversity advantage of GSTBC in free space optical (FSO) communication systems. Considering the combined effects of path loss, pointing error and atmospheric turbulence, the Meijer G function is used to derive the closed-form expression for the average bit error rate (ABER) of GSTBC-EFOGSM. Then, the ABER performance, data transmission rate, energy efficiency and computational complexity at the receiver of GSTBC-EFOGSM are compared with other optical spatial modulation schemes by simulation. In addition, the effects of key factors, such as data transmission rate, encoding ratio, number of photodetectors and modulation order, on the ABER performance of the system are also analyzed via simulation. Monte Carlo (MC) simulation is used to verify the correctness of the numerical simulation. The simulation results show that the GSTBC-EFOGSM system has better ABER performance and good performance gain.

Experimental and numerical investigations on buckling behaviours of axially compressed cylindrical–conical–cylindrical shells at elevated temperature

In this work, experimental and numerical studies are conducted to explore the buckling behaviours of cylindrical–conical–cylindrical assembly shells under axial compression at elevated temperature. Firstly, bucking experiments of six test specimens at 600 °C are carried out. Then, numerical method considering initial geometric imperfection is used to predict buckling behaviours of these assembly shells. Furthermore, the effects of key factors on buckling behaviours of cylindrical–conical–cylindrical shells are also discussed. Results indicate a good agreement between experimental data and numerical result based on the model with measured geometric imperfection, and the shell model with measured outer surface imperfection is adequate for buckling analysis. Comparatively, the buckling load predicted by the model with eigenmode imperfection is reasonably conservative compared with experimental result only when the amplitude of imperfection is close to the measured imperfection amplitude. In addition, the effects of material properties and geometry parameters, e.g., yield stress, ratio of radius to shell thickness and semi-vertex angle, on the load-carrying capacity and buckling mode of cylindrical–conical–cylindrical shells are investigated systematically. Finally, a strategy for buckling analysis of cylindrical–conical–cylindrical shells is proposed.

An active two-dimensional covalent organic framework for persulfate-assisted high efficiency photocatalytic degradation of rhodamine B

Covalent organic frameworks (COFs) have been widely used based on their ordered pore structure, inherent porosity, high specific surface area and excellent stability. Herein, the active two-dimensional COF (named HDU-25) photocatalyst was preformed by the solvothermal method, and the structure and morphology were characterized and analyzed. The effects of key factors on rhodamine B (RhB) degradation by HDU-25 were evaluated. The results showed that under suitable conditions, HDU-25 exhibited an excellent photocatalytic degradation rate of 99.9% for persulfate-assisted photocatalytic degradation of RhB, and HDU-25 also had superior stability and reusability. In addition, the mechanism of RhB degradation was investigated using free radical capture experiments and electron spin resonance (ESR) experimental analysis. The intermediates were detected by high performance liquid chromatography-mass spectrometry (HPLC-MS), and possible degradation pathways were suggested. The results of this research highlight the potential of HDU-25 photocatalysts to degrade organic dyes in wastewater.

Removal and mineralization of toluene under VUV/UV lamp irradiation in humid air: Effect of light wavelength, O2 and H2O

VUV/UV photodegradation is a promising method that utilizes energetic photons and reactive oxygen species (ROS) generated via the photo-dissociation of H2O and O2 to degrade VOCs. In the paper, we investigated the efficiency of removal and mineralization in humid air and the effects of key factors. Toluene of 4–20 ppm can be almost completely removed in 60 s and mineralization efficiency is above 55% at 25 min. 185 nm ultraviolet light plays a key role in the rapid removal and mineralization of toluene. Appropriate amount of O2 and H2O promote the removal of toluene due to the generation of ROS. Based on the intermediates and degradation pathway analysis, it is found that in the presence of O2, degradation pathways of toluene are more abundant and fewer linear-chain aldehydes are produced, thus resulting in higher mineralization efficiency. This work highlights the importance of practical application of VUV/UV photodegradation in humid air.

Structural behaviour and design of stainless steel end-plate beam-to-exterior column minor-axis joints

The structural behaviour of stainless steel end-plate minor-axis joints of I-section columns is investigated through comprehensive experimental and numerical studies. Four stainless steel end-plate beam-to-exterior column minor-axis joints were fabricated and tested subject to both monotonic and cyclic loading, wherein two joints were made of austenitic grade EN 1.4301 and another two joints were in duplex grade EN 1.4462. The obtained failure modes, structural properties and local characteristics were discussed. Meanwhile, advanced finite element (FE) models were generated by means of the ABAQUS software package, and were validated against the obtained experimental results, and the effects of key factors on structural behaviour of minor-axis joints were examined via subsequent parametric studies. The initial rotational stiffness and moment resistance of the tested joints were compared with the predictions from the existing design method, and a new design approach for the column web in bending and punching that can account for the strain hardening of stainless steels and the restraint from transverse stiffeners was proposed. The reliability of the novel design proposal was demonstrated by a statistical analysis of the ratios of test/FE over calculated results.

Analytical Study on the Pullout Resistance of Suction Caisson in Clay

Abstract The pullout resistance is a design consideration for suction caisson-supported offshore structures, such as offshore platforms and wind turbines. An analytical method is proposed in this paper to calculate the pullout resistance of a single caisson foundation embedded in clay. Comparisons with laboratory model tests were also made to verify the accuracy of the proposed analytical method. Parametric studies were conducted to investigate the effects of key factors on the pullout resistance of caisson. This study found the pullout force nonlinearly increases with the increase of caisson diameter squared but linearly increases with the increase of caisson–soil frictions. For caisson wall thickness over height ratio ranging from 0.00125 to 0.00325 and caisson diameter over height ratio ranging from 0.25 to 0.75, the normal stress decreases nonlinearly along with the depth of the caisson skirt wall and is heavily influenced by the skirt wall thickness but slightly influenced by caisson diameter.

Direct carboxylation of cellulose in deep eutectic solvent and its adsorption behavior of methylene blue

The surface of cellulose particles was carboxylated (2.44 mmol/g) in a deep eutectic solvent containing carboxylic acid. Based on the carboxyl content, the effects of key factors on cellulose carboxylation was systematically investigated. In addition, the reaction mechanism was studied by using liquid chromatography-mass spectrometry, and the influence of deep eutectic solvent containing carboxylic acid on the structure and physicochemical properties of cellulose during carboxylation was examined using different characterization techniques. The results showed that the type of carboxylic acid, cellulose particle size, and pretreatment methods significantly affect the carboxylation efficiency, degradation, and carbonization of cellulose. The internal crystal structure of cellulose did not change after the carboxylation reaction, while the surface crystal structure was destroyed by carboxylation, which greatly improved the dispersion and hydrophilicity properties of the product. The kinetics and thermodynamics of carboxyl cellulose adsorption were studied as well. Potential application of carboxyl cellulose in the adsorption of pollutants was demonstrated. This study provides a new method for the direct modification of cellulose in deep eutectic solvents, as well as a new sustainable strategy for modifying other materials.

Developing a model for chloride transport through concrete considering the key factors

The corrosion of chloride-induced on concrete is affected by many factors. In this research, an innovative empirical model was developed to predict the long-term chloride migration behavior in concrete, considering the effects of water-cement ratio, time, bonding effect, temperature, relative humidity, and concrete deterioration. The reliability and validity of the results evaluated by the empirical prediction model were verified by the chloride concentration data in concrete specimens exposed to the marine environment for 3, 5, and 10 years reported in the literature. Combined with the established empirical prediction model, the concrete model was regarded as a three-phase composite material composed of mortar, coarse aggregate, and interfacial transition zone. The effects of key factors on chloride migration were further analyzed by using the mesoscopic finite element numerical simulation method. It was observed that when temperature increases from 5 ℃ to 65 ℃, chloride diffusion depth rises by 3.3 times. When relative humidity increases from 20% to 100%, chloride diffusion depth rises by 4.3 times. Also, the water-cement ratio, concrete deterioration, and chloride binding effect have a non-negligible impact on chloride migration.

Performance evaluation of a novel CCHP system integrated with MCFC, ISCC and LiBr refrigeration system

This paper proposes a novel combined cooling, heating, and power (CCHP) system integrated with molten carbonate fuel cell (MCFC), integrated solar gas-steam combined cycle (ISCC), and double-effect absorption lithium bromide refrigeration (DEALBR) system. According to the principle of energy cascade utilization, part of the high-temperature waste gas discharged by MCFC is led to the heat recovery steam generator (HRSG) for further waste heat utilization, and the other part of the high-temperature waste gas is led to the MCFC cathode to produce CO32−, and solar energy is used to replace part of the heating load of a high-pressure economizer in HRSG. Aspen Plus software is used for modeling, and the effects of key factors on the system performances are analyzed and evaluated by using the exergy analysis method. The results show that the new CCHP system can produce 494.1 MW of electric power, 7557.09 kW of cooling load and 57,956.25 kW of heating load. Both the exergy efficiency and the energy efficiency of the new system are 61.69% and 61.64%, respectively. Comparing the research results of new system with similar systems, it is found that the new CCHP system has better ability to do work, lower CO2 emission, and can meet the cooling load, heating load and electric power requirements of the user side at the same time.

Economic Critical Resources for the Industrial Exploitation of Natural Gas Hydrate

AbstractSince the implementation of several pilot production tests were in natural gas hydrate (NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for industrial exploitation. Prior to the industrial exploitation of any given NGH reservoir, the economic feasibility should be examined. The first step of economic evaluation of a NGH reservoir is to know whether its resource amount meets the requirement for industrial exploitation. Unfortunately, few relevant studies have been conducted in this regard. In this study, the net present value (NPV) method is employed to estimate the economic critical resources required for the industrial exploitation of NGHs under different production scenarios. Sensitivity analysis is also performed in order to specify the effects of key factors, such as the number of production wells, gas price, technological improvement and tax incentive, on the economic critical resources. The results indicate that China requires the lowest economic critical resource for a NGH reservoir to be industrially exploited, ranging from 3.62 to 24.02 billion m3 methane. Changes in gas price and tax incentives also play significant roles in affecting the threshold and timeline for the industrial exploitation of NGH.