Concentration Of Solution Research Articles

Development of Fly Ash-Based Geopolymer Lightweight Aggregates

This research delves into the utilization of microwave hybrid heating as a curing technique for producing fine aggregates from fly ash. Various concentrations of alkali activator solutions were employed as binders to pelletize the fly ash (ranging from 0% to 10%). The resultant green fly ash-based geopolymer (FAG) aggregates were subjected to a 15-minute microwave kiln treatment. The microwave-sintered FAG fine aggregates, varying in sizes from 0.60 to 2.36 mm, were then utilized to fabricate 50 mm cubic cement mortar samples. Findings indicated that the density of FAG aggregates was approximately 36% lower than that of natural sand, while the water absorption capacity of FAG aggregates exhibited a fivefold increase compared to natural sand. Notably, cement mortar samples made with FAG aggregate of 4% alkali activator exhibited maximum compressive strengths of 31, 37, and 42 MPa at 7, 14, and 28 days of curing, respectively. These compressive strengths were only 12% lower than those of cement mortars made with natural sand across all curing periods. The use of microwave hybrid heating to transform fly ash into aggregates with sufficient strength appears viable, suggesting that these manufactured FAG aggregates could serve as substitutes for natural aggregates in concrete production

Electrospinning of Sm0.5Sr0.5CoO3-δ nanofiber cathode for solid oxide fuel cells

Sm0.5Sr0.5CoO3-δ (SSC) fiber-electrode materials were prepared via electrospinning in this work. The characteristics of SSC fibers are influenced by the parameters of electrospinning, specifically the nitrate concentration of the spinning solution, applied voltage, and the gap between the spinneret and collector. The as-prepared SSC fibers exhibited average diameters ranging from 240 nm to 6.49 μm, which contracted to 50 nm–2.53 μm after calcination at 800 °C. Symmetric cells with SSC fiber-electrodes demonstrated an area-specific resistance (ASR) ranging from 0.212 to 0.508 Ω cm2 at 700 °C in air. In addition to the morphology of SSC fibers, the average grain size of the SSC fibers also exhibited potential influence on their ASR performance.

Optical directional differential operation enabled visual chirality detection.

Directional differential operation can extract the changes of directional information from complex signals, and plays an important role in target recognition and texture image processing. Here, we propose an optical directional differential operation based on large cross-polarization rotation, and realize the visual detection of chiral enantiomers. By using cross-polarization rotation in a specified direction, we design a corresponding directional spatial spectral transfer function whose transmission efficiency increases as the incident angle approaches the Brewster angle. The differential direction can be adjusted by changing the initial polarization state, and can be used to detect the concentration of chiral solutions. Finally, we apply the directional differential operation to achieve the visual detection of chiral enantiomers.

Bioassessment of Cd and Pb at Multiple Growth Stages of Wheat Grown in Texturally Different Soils Using Diffusive Gradients in Thin Films and Traditional Extractants: A Comparative Study.

The bioavailability of heavy metals in soil is a crucial factor in determining their potential uptake by plants and their subsequent entry into the food chain. Various methods, including traditional chemical extractants and the diffusive gradients in thin films (DGT) technique, are employed to assess this bioavailability. The bioavailability of heavy metals, particularly cadmium (Cd) and lead (Pb), is also influenced by soil texture and their concentrations in the soil solution. The primary objectives of this experiment were to compare and correlate the assessment of the Cd and Pb bioavailability using the DGT technique and traditional extractants across two soil textural classes: sandy clay loam (SCL) and clay loam (CL) at two contamination levels: aged contaminated (NC) and artificially contaminated (AC). The specific objectives included assessing the bioavailability of Cd and Pb at different growth stages of the wheat plant and correlating the DGT-based bioassessments of Cd and Pb with their concentrations in various plant parts at different growth stages. This study also compared the effectiveness of the DGT method and traditional extraction techniques in assessing the bioavailable fractions of Cd and Pb in soil. The regression analysis demonstrated strong positive correlations between the DGT method and various extraction methods. The results showed that the wheat plants grown in the AC soils exhibited lower root, shoot, and grain weights compared to those grown in the NC soils, indicating that metal contamination negatively impacts plant performance. The concentrations of Cd and Pb in the wheat tissues varied across different growth stages, with the highest levels observed during the grain filling (S3) and maturity (S4) stages. It is concluded that the in situ assessment of Cd and Pb though DGT was strongly and positively correlated with the Cd and Pb concentration in wheat plant parts at the maturity stage. A correlation and regression analysis of the DGT assessment and traditional extractants showed that the DGT method provides a reliable tool for assessing the bioavailability of Cd and Pb in soils and helped in developing sustainable soil management strategies to ensure the safety of agricultural products for human consumption.

Effect of spacing, concentration of NaCl solution, and biasing of graphite electrodes towards conductometric sensor response

Effect of spacing, concentration of NaCl solution, and biasing of graphite electrodes towards conductometric sensor response

Therapeutic effects of LIPUS on the elasticity of injured tendons: animal experiment

Abstract This paper aims to explore the efficacy and duration of low-intensity pulsed ultrasound (LIPUS) treatment in improving the elastic properties of injured tendons through animal experiments. 48 healthy 3-month-old New Zealand white rabbits (weight 2.5-3.0 kg) were randomly divided into the Control group (n = 9) and model group (n = 39). The rabbits in the model group were injected with 0.2ml PGE2 mixed solution (concentration: 500 ng/0.2ml) into the Achilles tendon 2cm above the calcaneus, once a week, for 4 weeks, to build the Achilles tendon injury model. The Control group was injected with the same volume of PBS solution. Three rabbits were randomly selected from the Control and model groups for model validation, the model group was randomly divided into the Model (n = 6) and LIPUS (n = 30) groups. Then the LIPUS was randomly divided into the LIPUS1 (n = 6), LIPUS4 (n = 6), LIPUS7 (n = 6), LIPUS14 (n = 6), and LIPUS28 (n = 6) subgroups. Following interventions on days 1, 4, 7, 14, and 28, tendon elasticity was assessed by shear wave elastography (SWE). The elastic modulus of the Model, LIPUS1, and LIPUS4 groups exhibited a significant decrease compared to the Control group during the early stages of treatment. With prolonged treatment duration, the elastic modulus of LIPUS groups gradually increased. By day 7, no statistically significant difference in elastic modulus existed between the LIPUS7 and Control groups, indicating that LIPUS treatment had successfully restored the Achilles tendon’s elasticity to a healthy state. In summary, LIPUS therapy demonstrates the potential to effectively ameliorate the elastic properties of injured Achilles tendons.

Removal of Pb(II) ions from aqueous solutions using natural and HDTMA-modified bentonite and kaolin clays

This work focused on the removal of Pb(II) from aqueous solution using kaolin and bentonite clays modified with hexadecyl trimethyl ammonium bromide (HDTMA). The clays were characterized using a zetasizer, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Brunauer-Emmet-Teller (BET), Fourier-transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA). Factors that influence the adsorption of Pb(II) from aqueous solution, namely pH, contact time, adsorbent mass, ionic strength, temperature and initial Pb(II) concentration were investigated. The results show that HDTMA was successfully incorporated into the kaolin and bentonite clay structures. The most favorable parameters for the adsorption of Pb(II) ions onto all adsorbents was pH of 6.0, temperature of 25 °C and adsorbent mass of 200 mg. Adsorption isotherms and kinetic studies showed that the adsorption of Pb(II) onto kaolin, bentonite and organobentonite clays followed the Langmuir isotherm and pseudo-first order kinetic model, while the adsorption onto organobentonite was better explained by the Freundlich isotherm and pseudo-second order kinetic model. Maximum monolayer adsorption capacity of organobentonite, calculated from the Langmuir model was 18.75 mg/g, which is higher than that obtained for the unmodified bentonite (14.71 mg/g); while for organokaolin it was 2.26 mg/g, which is less than that of the unmodified kaolin (4.19 mg/g). Thermodynamic studies showed that the reactions were exothermic and unfavoured at high temperatures. The adsorbents also showed good removal efficiency for up to four regeneration cycles.

Seeding Layer Effect on the Microstructure of Hydrothermally Grown α‐Manganese Dioxide Nanowires on Three‐Dimensional Graphene Foam

AbstractHydrothermal synthesis is a straightforward approach for producing high‐yield manganese dioxide (MnO2) nanostructures with efficient morphological control at low temperatures. This study investigates the microstructural dependency of hydrothermally grown α‐MnO2 nanowires (NWs) on pre‐treatment conditions on the substrate surface. Within this scope, α‐MnO2 NWs were synthesized on chemical vapor deposition (CVD)‐based graphene foam (GF) substrates pre‐treated via potassium permanganate (KMnO4) solution as a seeding layer with different concentrations (0.025, 0.050, 0.075, 0.1 M). A direct α‐MnO2 NWs growth (without pre‐treatment) was also performed on GF by hydrothermal method. The seeding layer effect on the NWs growth was elaborated to comprehend the process‐structure correlations by characterizing the resultant graphene foam/α‐MnO2 nanowires (GF/α‐MnO2 NWs) nanocomposites through Scanning Electron Microscopy (SEM), Raman Spectroscopy, X‐Ray Diffraction (XRD), and X‐Ray Photoelectron Spectroscopy (XPS). SEM, XRD, and Raman Spectroscopy revealed the successful acquisition of highly crystalline α‐MnO2 in one‐dimensional nanowire morphology on the high‐quality GF. Moreover, XPS results confirmed that all nanocomposites comprise α‐MnO2 and graphene without chemical degradation. Consequently, slight changes in solution concentration of seeding layers caused a noticeable alteration in the nanowire's structure, which could ensure effective control of nanocomposite properties without sacrificing the high purity of each component.

Layered heterogeneous structures integrated device for multiplication, division arithmetic unit and multiple-physical sensing

A layered heterogeneous structure (LHS), consisting of silver, liquid crystal, and nonlinear dielectric layers, is proposed to realize functions of computing and sensing. By leveraging the optical Tamm state, the intrinsic absorption principle of liquid crystal, and nonlinear effects, the design of an integrated device capable of passive multiplication and division operations, along with high-performance multi-physical quantity sensing functionalities, is achieved. The given LHS exhibits Janus properties, with different physical functions manifested depending on the direction of electromagnetic wave (EW) propagation. During forward propagation of EWs, the LHS displays high and sharp absorptivity peaks at 774.8 and 1517.6 nm. The relationship between the two peaks approximates a frequency multiplication factor of 1.960, enabling signal multiplication. Furthermore, the two absorptivity peaks at different wavelengths facilitate the sensing of serum creatinine solution concentration and external pressure, with sensitivity (S), quality factors (Q), and figure of merit (FOM) of 266.76 μmol L−1/nm and 213.33 GPa/nm, as well as 248.76 and 348.22, 84.1 L (μmol)−1 and 49.06 GPa−1, respectively. During backward propagation of EWs, absorptivity peaks with distinct resolutions are observed at 1423 and 2809 nm, with a multiple relationship between them of 1.974, enabling frequency doubling for signal division. Additionally, the absorptivity curve facilitates temperature sensing over a wide range from 257 to 347 K. Owing to the unique temperature S of liquid crystal, different sensitivities and resolutions are observed at 257 to 297 K and 307 to 347 K, with S of 1.015 and 0.686 K/nm, and corresponding Q and FOM of 21.57 and 12.576, 0.076 K−1 and 0.003 04 K−1, respectively.

Photocatalytic degradation of Alizarin Red contaminant using Ag2CrO4@NiFe-LDH composite under visible light irradiation.

In this study, Ag2CrO4@NiFe-LDH nanoparticles were synthesized by hydrothermal method for photocatalytic degradation of Alizarin Red (AR) dye. Three composites with different molar percentages were prepared, among which 50%Ag2CrO4@50%NiFe-LDH composite was the best sample with a removal rate of 97.1% in AR degradation. Also, the properties, structure, and characteristics of pure Ag2CrO4 and NiFe-LDH and their composites were determined by XRD, FESEM, FTIR, EDX mapping, and UV-visible analyses. It was found that Ag2CrO4@NiFe-LDH composites with the formation of heterogeneous structure of Z-scheme, in addition to increasing the active sites and increasing the specific surface, decrease the recombination rate of pure Ag2CrO4 and NiFe-LDH. Also, the Box-Behnken design technique, which is one of the most common designs used in response surface methodology, was used to optimize the operating conditions and investigate the effect of 4 independent parameters: catalyst amount, solution concentration, pH, and light intensity. The importance of independent parameters and their interactions were determined by ANOVA. By means of numerical optimization, the optimal values of the selected parameters equal to 1.34 g/L of catalyst, concentration of 16.45 mg/L, pH = 10.74, and light intensity of 15.53 W were obtained as optimal conditions with a desirability coefficient of 1.00 and an absorption value of 89.34%. The closeness of adjusted R2 (0.9838) and predicted R2 (0.9507) values show that this model can be successfully used for prediction.

Performance and microstructure of red-mud-blended concrete under different aqueous environments

The effects of aqueous environments on the performances of red-mud-blended concretes (RMCs) were evaluated by measuring their compressive strength, water absorption, and porosity. The pH value, electrical conductivity, and heavy metal concentrations of the immersion solutions were measured to determine the effects of RMCs on the aqueous solutions. The hydration products and microstructures of RMCs were analyzed to determine the effect mechanisms. The results showed that the addition of red mud to concretes increases the apparent porosity and water absorption and decreases the compressive strength. Acidic environments exhibited the most significant effect on the performances of RMCs. In a neutral environment, C–S–H gel generation and a high Si/Ca ratio resulted in enhanced corrosion resistance for the RMC with 35 % red mud, and its compressive strength decreased by 15.07 % after 28 d of immersion. The pH value and electrical conductivity showed a rapid increase, indicating the leaching of soluble alkalis and a large number of ions during soaking. The electrical conductivity showed a rapid increase with the immersion time within 60 d, indicating the leaching out of a large number of ions. The heavy metal concentration and pH value were within the range specified by Chinese standard (DZ/T 0290–2015), which provides many references for evaluating the interaction between RMCs and the aqueous environment.

Sensory Profile of Candied Tomatodates Using the Just About Right Method

Candied tomato dates are processed candies made from tomatoes that are dried until they are shaped like dates. Sensory profiles are needed to obtain candied date tomatoes with the most optimal betel lime solution concentration treatment and blanching time based on penalty analysis methods (JAR and hedonic scales). This study used the just about right method combined with the hedonic scale (overall liking) in the treatment of candied date tomatoes with a concentration of betel lime solution (2%, 3% and 4% (b/b)) and blanching time (5 minutes, 10 minutes and 15 minutes). There are 17 sensory attributes that will be tested through the assessment of the JAR scale and the hedonic scale (overall liking). The data obtained was then processed using XLSTAT 2024 software. Based on the results of the penalty analysis, it was shown that the most optimal candied date tomatoes were candied date tomatoes with a concentration treatment of 3% betel lime solution and a blanching time of 15 minutes where there were 14 insignificant test attributes or p-value≥0.05. Meanwhile, there are only 3 sensory attributes that need to be optimized or p-value˂0.05, namely juicy texture (p-value = 0.002), sweet taste (p-value = <0.0001) and fruity taste (p-value = 0.017).

Research on the process of preparing fiber filtration membrane by centrifugal blowing electrospinning technology

AbstractCurrently, the problem of air pollution is getting more and more serious, especially the pollution of tiny solid particles (PM, particulate matter) in the air, which poses a great challenge to the environment and human health. Therefore, it is particularly important to develop air filtration materials with high filtration efficiency and low resistance to meet this challenge. In this study, we propose to prepare air filtration membranes by centrifugal jet electrospinning technology, design multifactorial orthogonal coupling experiments, and investigate the effects of key process parameters of centrifugal jet electrostatic spinning, including solution concentration, airflow rate, rotational speed, and voltage, on the fiber diameter and uniformity by applying the polar analysis of variance and analysis of variance. PAN‐BaTiO3 electret nanofiber filtration membranes with high efficiency and low resistance were prepared by combining the optimized process of centrifugal blowing electrospinning. Various characterization methods (tensile test, water contact angle test, surface charge test, filtration test) were used to evaluate the effect of different BaTiO3 electret contents (0%, 0.1%, 0.5%, 1%) on the comprehensive performance of the filtration membranes, and the electret filtration efficiency of the electret filtration membranes prepared by the present process reached as high as 96.56% with a pressure drop of 29 Pa.

Evaluation of wind erosion resistance of EICP solidified desert sand based on response surface methodology

Wind erosion is the primary cause of land desertification in arid and semi-arid regions. Enzyme-induced carbonate precipitation (EICP) will produce a solid coating on the surface of desert sand that inhibits wind erosion. Three critical variables for EICP treatment, including enzyme-cementation ratio A, cementation solution concentration B, and spraying volume of reaction solution C, were evaluated with three wind erosion-resistance indexes (surface strength, calcium carbonate content, and solidified layer thickness) of desert sand, and further optimized with the response surface methodology (RSM). The mass loss of the EICP-treated desert sand was studied by wind tunnel tests with wind speeds of 8–14 m/s and erosion times of 0–30 min. Material composition and microstructure of the EICP precipitates were investigated with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Results indicate that the three wind erosion-resistance indexes tend to rise with greater A and B values followed by a decline while monotonically increasing with C but the increments decrease when C>5 L/m2. The optimal solidification effect was reached when A=1.082:1, B=1.282 mol/L and C=8.70 L/m2, which corresponds to a maximum wind speed of 14 m/s for solidified desert sand. Large amounts of calcite crystals were produced in the EICP-treated sand and filled soil pores. The particle contacts transform from point contact to surface contact and the enhanced particle bonding induces a more compact soil skeleton. The above experiment evidence corresponds to increased surface strength and wind erosion resistance. The results of this study will provide an experimental foundation for the application of EICP technology to enhance wind erosion resistance of desert sands.

Effects of Electrochemical Hydrogen Charging Parameters on the Mechanical Behaviors of High-Strength Steel.

Extended exposure to seawater results in the erosion of the structural high-strength steels utilized in marine equipment, primarily due to the infiltration of hydrogen. Consequently, this erosion leads to a decrease in the mechanical properties of the material. In this investigation, the mechanical responses of Q690 structural high-strength steel specimens were investigated by considering various hydrogen charging parameters, such as the current density, charging duration, and solution concentration values. The findings highlighted the significant impacts of electrochemical hydrogen charging parameters on the mechanical behaviors of Q690 steel samples. Specifically, a linear relationship was observed between the mechanical properties and the hydrogen charging current densities, while the associations with the charging duration and solution concentration were nonlinear. Additionally, the fracture morphology under various hydrogen charging parameters was analyzed and discussed. The results demonstrate that the mechanical properties of the material degrade with increasing hydrogen charging parameters, with tensile strength and yield stress decreasing by approximately 2-4%, and elongation after fracture reducing by about 20%. The findings also reveal that macroscopic fractures exhibit significant necking in uncharged conditions. As hydrogen charging parameters increase, macroscopic necking gradually diminishes, the number of microscopic dimples decreases, and the material ultimately transitions to a fully brittle fracture.

Characterizing the concentration of ethanol-water solutions by oblique-incidence reflectivity difference combined with deep learning algorithms

The detection of ethanol–water solution concentration plays an important role in industries, medical care, food and other aspects, which has attracted much attention. In this paper, a 632.8 nm laser combined with the oblique-incidence reflectivity difference (OIRD) method was used to obtain a signal linearly related to the solution concentration and containing the information of the dielectric constant of the solution. Combined with a variety of deep learning algorithms, ethanol–water solutions with a volume concentration of 0–95 % are detected. Among them, the prediction accuracy of the MLP, CNN, LSTM, CNN + BiLSTM + Attention models were 93.65 %, 96.54 %, 97.12 %, 99.23 %, respectively. The experimental results indicate that the OIRD method can achieve rapid, non-destructive, accurate and reliable detection of ethanol–water solutions.

Room-temperature mL-to-μL quantitative liquid concentration device for cyclone flow.

Highly sensitive quantitative analysis of liquids is required in various fields. Analytical instruments and devices such as chromatography, spectroscopic analysis, DNA sequencers, immunoassay, mass spectrometry, and microfluidic devices are utilized for this purpose. Typically, the sample volume is at the milliliter scale, while the analysis volume is at the microliter scale. Consequently, most of the sample is discarded. Therefore, a universal volume interface is required to quantitatively concentrate samples from milliliter to microliter volume. This study introduces a liquid quantitative function to the cyclone concentration method using a millimeter-scale channel, which is highly suitable for controlling liquids at the microliter scale due to its high fluidic resistance against cyclone flow. This method enables the effective control of liquid concentration by cyclone flow. The optimum channel structure is investigated, and a 33-fold concentration of aqueous solutions is demonstrated. Finally, the concentration device is applied to measure molybdenum ions in a river.

De Novo Design and Characterization of Amphiphilic Peptides with Basic Side Chains for Tailored Interfacial Chemistries.

Lysine-leucine (LK) peptides have been used as model systems and platforms for 2D material design for decades. LK peptides are amphiphilic sequences designed to bind and fold at hydrophobic surfaces through hydrophobic leucine side chains and hydrophilic lysine side chains extending into the aqueous subphase. The hydrophobic periodicity of the sequence dictates the secondary structure at the interface. This robust design makes them ideal candidates for controlling interfacial chemistry. This study presents the de novo design and characterization of two novel peptides: LRα14 and LHα14, which substitute lysine with arginine and histidine, respectively, in the helical LKα14 sequence. This modification is intended to expand the LK peptide platform to a new basic interfacial chemistry. We explore the stability of the new LRα14 and LHα14 designs with respect to changes in pH and salt concentration in bulk solution and at the interface using circular dichroism (UV-CD) and vibrational sum-frequency generation spectroscopy, respectively. Notably, the structural stability of the peptides remains unaffected across a wide range of pH and ionic strength values. At the same time, the variation of side-chain chemistry leads to a wide spectrum of interfacial water structures. By extension of the LK platform to include arginine and histidine, this study broadens the toolbox for designing tailored interfacial chemistries with applications in material and biomedical sciences.

Electrospun Polymeric Fiber Systems Inoculated with Cyanoacrylate Tissue Adhesive: A Novel Hemostatic Alternative during Open Surgery.

Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This study comprises the development of a novel wound dressing, combining the excellent properties of polylactic acid (PLA) non-woven textile, as substrate, obtained through electrospinning, and a cyanoacrylate-based (CA) tissue adhesive, for rapid hemostatic action. Thus, the fabrication of electrospun PLA membranes at three different PLA concentrations, the design and manufacturing of the support system and the production of surgical patches were carried out. SEM and FT-IR methods were employed for analyzing the morphology as well as the indicative markers for the shelf life evolution of the obtained patches. PLA fibers with well-defined structures and a mean diameter varying between 4.6 and 7.24 μm were obtained with the increase of the concentration of the PLA solutions. In vivo tests on a rat model as well as peeling tests for good patch adhesion on liver fragments harvested from the test animals, with a limit for the strength of the liver tissue of 1.5 N, were carried out. The devices exhibited excellent adhesion to the parenchymal tissue and a long enough shelf life to be used with success in surgical procedures, also facilitating prompt hemostatic action.

Snapshot computational spectroscopy enabled by deep learning

Abstract Spectroscopy is a technique that analyzes the interaction between matter and light as a function of wavelength. It is the most convenient method for obtaining qualitative and quantitative information about an unknown sample with reasonable accuracy. However, traditional spectroscopy is reliant on bulky and expensive spectrometers, while emerging applications of portable, low-cost and lightweight sensing and imaging necessitate the development of miniaturized spectrometers. In this study, we have developed a computational spectroscopy method that can provide single-shot operation, sub-nanometer spectral resolution, and direct materials characterization. This method is enabled by a metasurface integrated computational spectrometer and deep learning algorithms. The identification of critical parameters of optical cavities and chemical solutions is demonstrated through the application of the method, with an average spectral reconstruction accuracy of 0.4 nm and an actual measurement error of 0.32 nm. The mean square errors for the characterization of cavity length and solution concentration are 0.53 % and 1.21 %, respectively. Consequently, computational spectroscopy can achieve the same level of spectral accuracy as traditional spectroscopy while providing convenient, rapid material characterization in a variety of scenarios.