BackgroundMetal corrosion causes tremendous economic losses, including Mg and its alloys. The development of protective coatings is a good strategy to alleviate or inhibit corrosion.MethodsHerein, a slippery liquid-infused porous surface (SLIPS) was fabricated on the AZ31 Mg alloy substrate, based on ZnAl-layered double hydroxide (ZnAl-LDH). Especially, the electrolyte pH was adjusted to synthesize ZnAl-LDH with different morphology to accommodate the most silicone oil for SLIPSs.Significant findingsA smooth and homogeneous liquid layer was stably anchored in the ZnAl-LDH, forming a SLIPS. Although water contact angle was less than 150° for the SLIPS, the water droplet can easily slide on the surface, presenting low adhesion to the external species. The SLIPS showed the best corrosion protection, with the lowest corrosion current density of 5.01 × 10−9 A cm−2 and largest impedance modulus of 4.92 × 107 Ω cm2. Moreover, a long-term immersion test and stability examinations in harsh conditions were carried out to further evaluate the performances of superhydrophobic surface and SLIPS. The much more stable liquid layer than air pockets made the SLIPS perform better and provide reliable corrosion protection. Therefore, SLIPSs can further promote the wide applications of Mg alloys.

Lignin can be a sustainable source of aromatic compounds, whereas the utilization is limited because of its complex three-dimensional structure. Organosolv method is promising for the valorization of lignin because of its mild conditions as compared with industrial pulping processes. Aromatic aldehydes, widely used in various industries, are obtained by catalytic oxidation of lignin. Organosolv treatment of various types of lignocellulose in water/1-butanol solvent was conducted using a batch type reactor. During the solvent removal from 1-butanol phase containing organosolv lignin, the concentrated lignin was denatured, which was evaluated by measuring particle size distribution and thermal decomposition behavior of the lignin. The recovery procedure of lignin was improved, and the extraction of organosolv lignin from 1-butanol phase to alkaline solution was developed. The improved extraction method definitely showed a higher yield of aromatic compounds regardless of the type of lignocellulose, yielding 14 C-mol% of aromatic aldehydes after alkaline oxidation of willow-derived lignin. After the alkaline oxidation reaction, a simple solvent fractionation was applied for refining the oxidized products. The solvent fractionation of the oxidized products was achieved using ethyl acetate and n-heptane. n-Heptane-soluble fraction selectively contained the lighter fraction with maintaining the content of aromatic compounds.

BackgroundIt is crucial to predict the cavern development and eliminate the cavern effect in time for achieving efficient mixing of pseudoplastic fluids.MethodsThe cavern developments of xanthan gum solutions (a typical pseudoplastic fluid) stirred by dual-impellers of perturbed six-bent-bladed turbine (6PBT) were researched numerically based on laminar flow model.Significant FindingsThe results showed that the values of the power consumption obtained by the numerical calculation agreed well with the data measured by the stirring experiment, which validated the laminar flow model established. The fluid rheology had little influence on the cavern shape and its development. The cavern produced by the double-layer impeller would gradually developed from the initial separation state to the overall cylindrical shape with the increase of the speed. When the upper and lower caverns were in state of separation, the changes of their height diameter ratio of the were no longer a constant value. After the integration of upper and lower caverns, the whole cavern first grew rapidly along the axial direction to the top liquid level, and then continued to expand along the radial direction. When the cavern volume ratio Rc reached 90%, it could be considered that the cavern effect was eliminated.

BackgroundThe electrical double layer capacitors (EDLCs) have been commercially available and useful in the daily lives. Nevertheless, conventional EDLCs have reached their limit in terms of cell capacitance and cell voltage. The resultant low energy density urges researchers to improve either the maximum cell voltage or the specific capacitance to obtain a high-energy-density supercapacitor. In a fixed voltage window, the electrochemical activation (EA) method has been demonstrated to effectively enhance the specific capacitance of certain carbons with small surface areas.MethodsProgress that has been made since the introduction of this EA method in 1998 will be systematically discussed. The choice of (1) carbon materials with different properties, (2) electrolytes composed of various salts/solvents, and (3) binders that have diverse chemical/mechanical properties, proves influential in determining the resultant capacitive performance after the EA process.Significant findingsAlthough the EA mechanism has been intensively investigated and described as the irreversible intercalation of ions into graphitic regions in initial charge-discharge steps, the interplay amongst carbon, electrolyte and binder has not been fully understood. Therefore, in this article, a few research topics have been recommended to inspire further research interest in order to improve the EA method for practical applications.

BackgroundNowadays, drugs have been developed widely for the remediation of different microbial diseases. However, the presence of these compounds have influence on the water bodies. Thereupon, the preparation of inexpensive and efficient catalysts for the antibiotics degradation is important for the treatment of toxic contaminant in water.MethodsThe ternary NiCo2O4-Bi2O3-Ag2ZrO3 nanocomposite has been presented through a facile co-precipitation methods. The as-prepared nanocomposites was studied for the decomposition of metronidazole (MTN) under the visible light, and characterized by different analysis such as TEM, UV-vis, XPS, SEM, FT-IR, EIS, ESR, BET, and PL techniques.Significant findingsThe determined band gap values of Ag2ZrO3, Bi2O3, NiCo2O4 and NiCo2O4-Bi2O3-Ag2ZrO3 nanocomposites were 2.67, 2.45, 2.18 and 1.92 eV, respectively. The degradation efficiency of NiCo2O4-Bi2O3-Ag2ZrO3 under visible light displays the 100.0% decomposition attained in 80 min. The important parameters such as neutral pH, 4.0 g/L of catalyst dosage, and 5 mg/L of MTN concentration were found to be favorable for this reaction. The great recyclability attributes of the prepared catalyst were discerned after five successive cycles. The toxicity of the degraded MTN products were harmless and non-toxic. The scavenging test revealed that ·OH and ·O2− were the important radicals in the degradation of MTN by NiCo2O4-Bi2O3-Ag2ZrO3. The fabricated NiCo2O4-Bi2O3-Ag2ZrO3 was also investigated for the antimicrobial activity.

BackgroundDeveloping a novel chitosan porous microsphere with outstanding adsorption performance and magnetic separation function is significant for recycling and purification in wastewater treatment applications.MethodsGO@Fe3O4 (magnetic graphene oxide nanocomposite, MGN) was synthesized by a hydrothermal method, and magnetic chitosan/GO@Fe3O4 porous microspheres (MCMS) were fabricated via inverse emulsion method combined with simple microfluidic technique. The influence of MGN on the microstructures, magnetic separation performance and thermal stability of MCMS was characterized and the efficiency in removing Congo red (CR) from aqueous solutions was evaluated.Significant FindingsThe incorporation of MGN can significantly improve the adsorption performance of MCMS microspheres. The maximum adsorption amount of MCMS for CR achieved was around 395.8 mg g-1 at 308 K. MCMS also exhibited excellent magnetic separation performance and remarkably enhanced thermal stability. Besides, the pseudo-second-order kinetic model can describe the adsorption process for CR well, and the adsorption isotherms closely obeyed the Langmuir isotherm model.

BackgroundCasing and tubing for oil and gas wells are frequently made of steel alloys. Many corrosive gases, organic acids, salts, and other contaminants are present in the fluids of oil and gas wells, which hurt their productivity, efficiency, and continuous production. The common corrosive species include carbon dioxide (CO2), hydrogen sulfide (H2S), water (H2O), organic acids (HCOOH, CH3COOH etc.) and salts (NaCl, CaCl2, MgCl2, NH4Cl etc.) that can cause the corrosion of metals at any stage of production, purification, storage and transportation processes.MethodsThe purpose of the current article is to cover the corrosion of oil and gas well casing and tubing and corrosion mitigation techniques.Significant FindingsNumerous factors influence the corrosion rate in these wells, and various management techniques and procedures have been implemented to address corrosion-related problems in oil and gas wells. Corrosion-resistant materials are one of the most popular and frequently used techniques. To prevent internal pipeline corrosion, anti-corrosive and wear-resistance coatings are also utilized. Another frequent method against corrosion is using scavengers, primarily for H2S and O2, to lessen the corrosivity of the well fluids. The most popular H2S-scavenging technique uses alkaline solutions and activated carbon. Triazine and aldehydes are the most common and efficient non-generative H2S scavengers. The use of corrosion inhibitors is one of the most practical and cost-effective ways to prevent corrosion in well casing and tubing. The corrosion inhibitors adsorb at the point where corrosive fluids and internal pipelines interface, preventing the corrosive attack.

BackgroundCiprofloxacin is a commonly prescribed antibiotic drug whose solubility has not yet been completely studied. In this research, its equilibrium solubility at temperatures from T = (278.15 to 318.15) K in 13 neat solvents, namely, namely: 1,4-dioxane, polyethylene glycol (PEG) 600, PEG400, PEG300, N-methyl-2-pyrrolidone (NMP), PEG200, acetonitrile, N,N-dimethylformamide (DMF), ethanol, dimethyl sulfoxide (DMSO), methanol, ethylene glycol and water, is reported.MethodsFlask shake and UV–vis analysis were used for solubility determinations at different temperatures. Bottom solid phases were analyzed by DSC.Significant findingsMole fraction solubility of ciprofloxacin (x2) increases when temperature arises in all solvents. It varies from x2 = 4.11 · 10–6 in neat water to x2 = 1.55 · 10–3 in neat PEG200 at T = 298.15 K. Solubility behavior was adequately correlated by van't Hoff, van't Hoff-Yaws and Apelblat model. From the variation of solubility with temperature the apparent thermodynamic analysis of dissolution was performed in all the solvents. Total Hildebrand solubility parameter of ciprofloxacin (δ2) was calculated based on groups’ contributions by means of both the Fedors and the Hoftyzer-van Krevelen methods as δ2 = (26.4 and 25.7) MPa1/2, respectively. Otherwise, Hansen solubility parameters and total Hildebrand solubility parameter were also determined by using the Bustamante method from experimental solubility values in 16 neat solvents obtaining δ2 = 25.2 MPa1/2. Finally, KAT-LSER model was also employed to evaluate the role of different intermolecular interactions on the dissolution of ciprofloxacin.

BackgroundNon-Newtonian fluids are frequently present in many natural phenomena and industrial processes. This research focuses on free convection of Ostwald-de Waele fluid in a square enclosure equipped with a conducting circular body of constant internal volumetric heat flux.MethodsThe multiple-relaxation-time lattice Boltzmann approach is used for the numerical simulations of this physical problem. The 2-dimensional 9-discrete velocity (D2Q9) model is applied to the hydrodynamic field and the 2-dimensional 5-discrete velocity (D2Q5) model is used to thermal field. The bounce-back condition coupled with the quadratic interpolation is employed at circular boundaries.Significant findingsThe results show that the increase in the volumetric heat generation reverses, partially or completely, the direction of heat transfer on the hot left wall. Moreover, the employment of a dilatant fluid instead of pseudoplastic and Newtonian fluids leads to an increase in the maximum temperature in the case of a heat-generating obstacle.

BackgroundMultistage compartmented agitated column (MSAC) is widely used in extraction and chemical reaction. Interstage backmixing determines reactor performance, which is controlled by open channel area and its attaching draft tube in divider stage. However, the relation between backmixing and flow pattern condition within different internal structures and impeller types is still confused. In this work, the backmixing characteristics in a four stage MSAC have investigated, in order to explore the effect of opening channel radial position, draft tube direction and impeller type.MethodsThe flow condition especially for backmixing in MSAC is simulated by CFD. The backmixing intensity in each case is determined based on the simulated RTD normalized variance.Significant FindingsResults show that the variation of backmixing intensity is clarified with the analysis of circulation loop flow pattern, flow resistance, mixing intensity and impeller feature. The backmixing rate decreases first and then increase along the radial position, which has controlled by the fluid circulation loop. The backmixing rate reduced with the adding of draft tube due to the increasing flow resistance. Furthermore, strong mixing lead to higher backmixing intensity, and the axial flow impeller features with large backmixing intensity under unit stirring powder density.

Abstract not available

BackgroundReclamation activities should be combined with the actual functional requirements of engineering sea areas. The contradiction between major reclamation activities and Marine ecological protection should be coordinated according to the local natural conditions, so as to put forward reasonable and feasible ecological construction plans.MethodsThis paper takes the Taiping Bay reclamation project of Dalian Port as an example, and based on the analysis of the impact of the regional historical reclamation on the coastline, hydrodynamics, water quality, marine ecological environment, and other factors. Combined with the results of numerical simulation, the realization and effectiveness of the marine ecological restoration and compensation scheme are described in detail. Although the reclamation project will bring about ecological and environmental problems, it is still an effective means to "effectively alleviate the contradiction between land supply and demand in coastal areas, expand development space and promote rapid economic development".Significant findingsThis paper puts forward suggestions to realize the coordinated development of marine economy and ecological protection from the reclamation land control policy and ecological restoration measures.

BackgroundIn this study, the fluid-induced vibrations of a long cylinder placed in the cross flow of a fluid with Reynolds number 325 have been investigated using ANSYS CFX 11. For this purpose, a middle section of the cylinder is considered in two-dimensional geometry and the damping and stiffness of the tube are modeled with appropriate springs and dampers. Since the frequency of the vortex shedding around the cylinder can exert an oscillating force on the cylinder, the effect of the applied force on the drag, lift and vibration path of the cylinder has been investigated. Also, by changing the natural frequency of the structure, different vibration modes and lock-in phenomenon have been investigated.MethodsVarious machine learning approaches have been used for predictive analysis where numerical data are generated to train intelligent algorithms for prediction errors. Different machine learning approaches such as long short-term memory (LSTM), multilayer perceptron (MLP) and support vector regression (SVR) are employed to optimize the prediction of drag and lift coefficient, vibration path of the cylinder and average Nusselt on the cylinder in terms of the natural frequency of the structure. This work proves that machine learning models are capable to predict the complex behavior of fluid flow in systems where flow-induced (FIV) vibration is coupled with heat transfer.FindingsIn the presented results, the Lissajous pattern in the form of number 8 was observed in the lock-in mode and the heat transfer in this mode shows an increase of about 13 percent compared to the fixed cylinder mode

BackgroundDirected evolution plays a crucial role in accelerating genetic development to obtain superior enzyme variants with high tolerance and activity. Under nature evolution, Mesorhizobium loti carbonic anhydrase (MlCA) stands out as one of the fastest metalloenzymes involved in carbon dioxide capture and sequestration (CCS). However, challenge arises when expressing the recombinant MlCA which affects its total catalytic function. Therefore, we aim to evolve MlCA by enhancing protein production and elevate catalytic efficiency in genetically Escherichia coli.MethodsA growth-dependent CRISPRi-based high-throughput screening platform DEPEND-2.0 with down-regulating essential gene was established. The in vivo target-specific MutaT7 mutator was employed to evolve MlCA and screened the mutants using DEPEND-2.0 based on cell growth. Structure prediction was further applied to analyze the mutant while the degenerated or definitive codons were designed to investigate the codon influence on the mRNA and enzyme production.Significant findingThe DEPEND-2.0 system, utilizing chromosomal dCas9, effectively inhibited cell growth by targeting the promoter region with sgRNA which maintained a repression rate of 65.4% at 4 h using high-copy RSF plasmid. Structural prediction using Alphafold revealed that a mutation introduced by MutaT7 at P105S resulted in a 99% loss of intrinsic activity due to the disruption of hydrogen bonding. Furthermore, synonymous codon designs demonstrated that AT-rich codons at the 5’ terminus of a 30-bp sequence exhibited higher mRNA levels and improved recombinant protein expression. Finally, the MlCA variant with A-rich codons (i.e., MA) effectively facilitated CO2 biomineralization, displaying high durability with 72% residual activity after five repeated reactions, ultimately accumulating 193 mg of CaCO3.

BackgroundRemoval of suspended kaolin at low concentration (0.25 wt.%) is tedious hence not investigated at random. An architecturally decorated semi-synthetic flocculant derived from Xanthan gum or XG, has been synthesized and specifically used to unsettle the stable kaolin suspension with high efficiency.MethodsHyperbranched Polyacrylamide or HBPAM was grafted onto XG following Strathclyde method whereby the extent of hyperbranching of PAM was controlled by the molar ratios of brancher (methylene-bis-acrylamide or MBA) to chain transfer agent (dodecane thiol or DDT). The chemical structure was established through various analytical characterization.Significant findingsIt was evident that the copolymer with maximum extent of branching (70.5%, designated as H3) exhibited fastest settling time as well as lowest turbidity simultaneously, especially at pH 7 (58 secs, 70 NTU) and at the isoelectric point (pH 4, 76 secs, 30 NTU) as compared to other hyperbranched and linear grafts of XG.

BackgroundWhen organic dyes or heavy metal cations are present in wastewaters, it is often necessary to add sacrificial molecules so that catalysts can effectively remove these pollutants. However, when organic dyes and heavy metal cations coexist, the composite removal rate of both contaminants by a few specific catalysts is higher, and no sacrificial molecules are needed.MethodsHerein, molybdenum trioxide (MoO3)‒reduced graphene oxide (rGO) composites were synthesized using a two-step microwave hydrothermal method. The samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray microanalysis. The photocatalytic degradation/reduction ability of the catalysts was evaluated under irradiation from a 300-W Xe lamp.Significant findingsIn the presence of H2O2, MoO3-rGO exhibited good degradation efficiency for rhodamine B (RhB) dye. Cr(VI) reduction over MoO3‒rGO occurred more favorably in an acidic environment (pH = 2). Moreover, when RhB and Cr(VI) coexisted, the composite removal rate of both contaminants was higher, and no sacrificial molecules were needed. The dual synergistic removal of RhB and Cr(VI) occurred through the combination of the photosensitized and photocatalysis mechanisms accompanied by rGO-mediated charge transfer.

BackgroundThe magnetohydrodynamics (MHD) are highly relevant to practical applications, including marine propulsion and hydrogen production etc. For better implementation to applications, typical characteristics of the MHD bubbly jet, such as the size distribution and motion of oxygen and hydrogen bubbles, need to be well realized.MethodsThe MHD bubbly jet generated by high current density associated with strong permanent magnet is experimentally investigated. Two fields of view are taken to analyze the details of micro-sized bubbles and the whole pattern of bubbly jet. To couple the magnetoelectric effects and bubble dynamics, the Reynolds number based on the Lorentz force ReL is applied in the parametric analysis.FindingsDependence of the mean size of bubble on the current density is generally verified. Two regimes regarding the bubble sizes are distinguished. The proposed mechanisms of these two regimes are supported by the pattern of bubbly jet. For ReL≤2000, size of bubble monotonically increases with current density, so that referred to as the electrochemistry regime. Nevertheless, the size of bubble remains nearly unchanged for ReL>2000, referred to as the flow regime in which the turbulent breakup of the bubbly jet core starts to evolve.

BackgroundThis work adopts an efficient method including thermal calcination, surface hydroxylation, and hydrothermal cutting to synthesize graphitic C3N4 quantum dots (CNQDs) for detecting metal ions in aqueous solutions.MethodsFunctionalized CNQDs, ranged from 2 to 6 nm in particle size, were of layered crystalline and contain a large amount of surface functionalities such as carbonyl, carboxylic, and amino groups. The CNQD suspension exhibited a maximal fluorescence intensity at 420 nm with high quantum yield of 13.6% under UV irradiation.Significant findingsThe CNQD suspension demonstrated superior sensitivity and selectivity toward iron ions with ppm-level detection limit in liquid phase. The Stern-Volmer analysis revealed that CNQD suspension was appropriate for the detection of Fe3+ and Fe2+ ions with LOD of 6.5 and 7.7 ppm, respectively. The fluorescence quenching mechanism of CNQD suspension mainly originates from a strong interaction between the ions and the surface functionalities followed by the photoinduced energy transfer effect, thus inducing the fluorescence extraction. Moreover, the CNQD suspension also offers a satisfactory biocompatibility toward 3T3 cell after 24 h. Accordingly, the robust design of CNQDs developed in this work paves the way for developing highly sensitive and selective probes for detecting target species in aqueous solutions.

BackgroundThe high toxicity of landfill leachate has motivated to an investigation of economical and ecological treatment prior releasing into environment. Recently, microalgae have emerged as an alternative method due to its ability to recover nutrient and potential for bio-fuel production. However, the high concentrations of inhibitory compounds and ammoniacal nitrogen in young landfill leachates require high dilutions for microalgae to thrive. Hence, this study aims to evaluate the performance of microalgae by using stabilized landfill leachate with lower to no dilutions in nutrient removal, biomass and lipid production.MethodsLeachate concentrations of 33, 44, 66, 89 and 100 v/v% were initially treated with the microalgae C. vulgaris. Parameters of chemical oxygen demand (COD), ammoniacal nitrogen (NH3–N), orthophosphate (PO43−), total phosphorus (TP) and colour removal were evaluated. Cost analysis was conducted to evaluate the economical appropriateness.Significant findingsThe highest removals were achieved at 43.67% of COD, >97% of NH3–N, 79.26% of PO43−, 77.64% of TP and 44.04% of colour. Highest biomass yield obtained was 220 mg/L by 89 v/v% of leachate concentration with 8.14% of lipid yield. Cost of treatment was calculated to be ∼$0.02 per m3 leachate. The feasibility of stabilized landfill leachate treatment without any dilutions using microalgae was attained as they can survive amidst this condition, perform nutrient removals, and produce biomass simultaneously.

BackgroundThe efficient capture of iodine and the reduction of CO2 emissions has become increasingly important in recent years due to their potential threats to human health and the environment. Hypercrosslinked Porous Organic Polymers (HPPs) are considered excellent adsorbent materials for these purposes due to their high surface areas, controllable structures, and thermal/chemical stabilities.MethodsThis work aimed to produce Fe-Bi HPP and An-Bi HPP materials for use in I2 uptake and supercapacitors applications. The preparation of these materials involved utilizing the Friedel-Crafts reaction of Fe-Di imidazole and An-Di imidazole with 4,4′-bis(chloromethyl)-1,1′-biphenyl (Bi-2Cl) in the presence of anhydrous FeCl3.Significant findingsThese materials exhibited a narrow range of pore sizes in the micropore range and had a high specific surface area of approximately 850 m2 g−1. According to the results of the electrochemical analysis, the Fe-Bi HPP demonstrated an energy density of 21 Wh Kg−1 and capacitance of 147 F/g. The adsorption experiments demonstrated the effectiveness of both materials in capturing iodine. The Fe-Bi HPP has superior efficiency compared to the An-Bi HPP, which can be attributed to its larger surface area and the presence of the ferrocene unit. It exhibits an impressive I2 adsorption uptake of 112.84 mg g−1.