Mass Ratio Of Solution Research Articles

Dynamic characteristics and performance analysis of a double-stage energy storage heat transformer with a large temperature lift

Intermittence and low grade are significant barriers for the widespread application of renewable/waste energy. An absorption energy storage heat transformer with adequate energy storage and temperature lift characteristics effectively addresses this challenge. An advancement in this technology is the double-stage energy storage heat transformer (DESHT), which further enhances the range of temperature upgrade through twice temperature lifts. This paper proposes a time-dependent approach for a comprehensive study of the DESHT cycle with a working pair of LiBr/H2O. Firstly, the dynamic characteristics of the DESHT cycle are shown. Subsequently, the effects of discharging temperatures, charging temperatures, and solution mass ratio on cycle performance are analyzed. Results show that the DESHT cycle can achieve a temperature lift from 35 °C to 55 °C. 90 % of the total storage capacity can be reached in 60–70 % of the total charging time. The maximum discharging time per unit of charging time is achieved at a temperature lift of 45 °C. Besides, compared to the conventional double-stage absorption energy storage cycle, the DESHT cycle shows a higher exergy efficiency. Optimizing the solution mass ratio can enhance the cycle performance. These findings can serve as a valuable reference in exploring the DESHT cycle.

Development of conditions for obtaining oil from sunflower oil hydration waste

The object of the study is the process of treatment of sunflower phosphatide concentrate using sodium chloride solution. Hydration is a stage of oil refining. The waste of the process is a phosphatide concentrate, the disposal of which is dangerous to the environment. The concentrate contains valuable components – oil and phosphatides. An important task is to separate these components for effective use in various industries. The process of extracting oil from phosphatide concentrate by hydration in the presence of sodium chloride solution was investigated. The influence of the concentrate treatment conditions on the oil yield was determined. A sample of concentrate according to SOU 15.4-37-212:2004 (CAS 3436-44-0) was used: mass fraction of moisture and volatile substances – 2.8 %, mass fraction of phosphatides – 41.5 %. The concentrate was treated with sodium chloride solution with a concentration of (5–20) %. The hydration time was 25 min., the temperature was 45 °C, and the mass ratio of the sodium chloride solution to the concentrate was 1:1. Conditions for the concentrate treatment were determined: the concentration of sodium chloride solution was 15 %, settling time was 5 hours. At the same time, the yield of oil was 86.9 %. The parameters of the extracted oil were determined: acid value 2.8 mg KOH/g, peroxide value 3.2 ½ O mmol/kg, mass fraction of moisture and volatile substances 0.12 %. According to these indicators, the extracted oil corresponds to first-grade unrefined unfrozen sunflower oil according to DSTU 4492. The mass fraction of phosphorus-containing substances in terms of stearooleolecithin was 1.7 %, which slightly exceeds the standard value. The research results make it possible to process hydration waste and obtain oil, which is a raw material for the products of many industries. This will help solve the problem of disposal of environmentally hazardous waste and improve the state of the environment

Preparation and Characterization of Red Mud-Based Geopolymer Composited with Rice Husk Ash for the Adsorption of Bromocresol Green in Aqueous Solution

Geopolymer-based industrial waste as red mud (RM) was successfully obtained in the presence of different loadings of rice husk ash (RHA). During the preparation, the added amounts of RHA in the geopolymer composition were varied from 10 to 50 % when the mass ratio of binder solution (Na2SiO3) and activated alkali-metal solution (NaOH 7 M) were 2.5 and the curing condition was fixed at 333 K within 24 h. For characterization, the surface morphology was evaluated by scanning electron microscope (SEM) equipped with the energy-dispersive X-ray, which detected the distribution of elements before and after the geopolymerization. To indicate the formation of geopolymer, Fourier–transform infrared spectroscopy (FT-IR) was used. The effect of the loading amounts of RHA on the Brunauer–Emmett Teller (BET) surface area value and Barrett–Joyner–Halenda (BJH) pore size of the obtained geopolymers were determined using a nitrogen gas adsorption instrument. In the bromocresol-green (BG) adsorption performed at pH 2, the higher addition of RHA in the geopolymer composition enhanced the adsorption capacities within 180 minutes. In addition, the adsorption behavior of the mixed geopolymer to BG fits well the Langmuir model, indicating that the adsorption occurs on the homogeneous monolayer surface of geopolymer. From this study, the RHA could be a natural potential filler to improve the BG-uptake of RM-based geopolymer in wastewater treatment.

Investigating the effects of testing protocol factors on chloride binding capacity in cementitious materials

This study investigates the influence of testing protocol factors, such as the degree of saturation (DoS), exposure solution composition, sample shape, and the solid-to-exposure solution mass ratio (SLR), on the measured chloride binding capacity of cementitious systems. Samples underwent varying degrees of saturation, including vacuum-saturated, partially saturated, and oven-dried conditions. The exposure solution composition included calcium, potassium, and sodium ions, in addition to pure sodium chloride. Different sample forms (powdered, crushed, and disk-shaped) were explored. Three SLRs of 1:3, 1:6, and 1:10 were also examined for their impact on chloride binding. The results indicated that DoS significantly influences chloride binding, with vacuum-saturated samples exhibiting higher binding capacity than partially saturated and oven dried samples. Additionally, the findings showed that samples in solutions containing additional ions had reduced binding capacities compared to pure chloride solutions. Increasing the sample surface area by crushing or powdering it led to an increase in chloride binding capacity compared to solid, disk-shaped specimens. Lastly, the results demonstrated that increasing the SLR can enhance the binding capacity of the system.

Compression Behavior of Rubber–Bentonite Mixture under Different Salinities

This study investigated the engineering properties of a rubber–bentonite mixture under different salt solution concentrations, mass ratios, and consolidation pressures. In addition, the effects of different solute ion concentrations on the compression index of the samples were compared. The results showed that the compression coefficient could be reduced effectively by increasing the weight percentage of rubber without being affected by the salt solution. However, with the increase in the salt solution concentration, the compression coefficient of mixed materials with different mass ratios increased, and when the salt solution concentration exceeded 0.5 mol/L, the compression coefficient increased more obviously. In a 0.1 mol/L NaCl solution, the addition of different levels of rubber could increase the compression modulus of the mixed material and reduce the compression ratio of the mixed material. This showed that in an environment with a low salt solution concentration, adding rubber into the mixed material could enhance its compressive deformation resistance. However, when the rubber content exceeded 50%, significant pores appeared in the sample, and the effect of high salt solution concentration intensified. The rubber content also had an effect on the swelling properties of soil, and the degradation of rubber in the salt solution showed reduced mechanical properties. This emphasizes the need to consider the stability and resistance of saline–alkali areas to salt erosion.

Study of fly ash-slag geopolymer mortar as a rapid strengthening agent for concrete structures

A fly ash-slag geopolymer mortar (GPM) was developed as an efficient bond material for rapidly strengthening concrete structures. To determine the most significant factors affecting fluidity, setting time, and early compressive strength, we studied the following six factors using an orthogonal test: the amount of slag in the binder (SL/B), the mass ratio of sodium silicate to sodium hydroxide (SS/SH), the molarity of NaOH (MN), the mass ratio of alkali solution to binder (A/B), the superplasticizer addition to binder (SP/B), and the mass ratio of fine aggregates to binder (F/B). Different admixtures have been studied to improve the fluidity of the GPM. Bonding tests were conducted to investigate the differences in the bond behavior of the GPM. The results indicate that SL/B and A/B significantly affected the properties of the GPM. Increasing SL/B was beneficial for enhancing the early compressive strength of the GPM and decreasing its fluidity and setting time, whereas A/B exhibited the opposite trend. It is challenging to meet the requirements of high early strength and fluidity of the GPM by only changing the chemical composition, and admixtures should be added. The 1-day GPM without the interfacial agent exhibited a bond strength similar to that of the PCM at 7 days and the existing interfacial agent was not suitable for the early-strength GPM.

Study on mechanical properties of metakaolin based geopolymer pervious concrete

In this study, geopolymers were used as binder materials and large-sized aggregates as coarse aggregates to prepare pervious concrete. Design different alkali activator modulus, concentration, and coarse aggregate: geopolymer binder materials in mass, and test the physical, and mechanical properties. According to the compression test, the stress-strain curve of the metakaolin-based polymer pervious concrete was obtained, and the elastic modulus and strain were analyzed. The test results show that: with the increase of the modulus of the alkali activator, the compressive strength and splitting tensile strength show a trend of increasing first and then decreasing. The higher alkali activator concentration and the ratio of the crude aggregate to the polymer binder material are detrimental to the development of strength in pervious concrete. The mass ratio of geopolymer binder material to coarse aggregate is 1: 5, the concentration of alkaline activator is 40%, the modulus is 1.3, and the mass ratio of alkali activator solute (sodium silicate+sodium hydroxide) to metakaolin is the geopolymer pervious concrete prepared at 0.35 has higher strength and water permeability.

Development of machine learning models for the prediction of the compressive strength of calcium-based geopolymers

Compressive strength is an important mechanical index that determines the mixture design of geopolymer, and its accurate prediction is essential. The existing experiment-based and statistical methods are time-consuming, labor-intensive and inaccurate. This study aims to develop an effective, reliable and interpretable machine learning (ML) model for predicting the compressive strength of calcium-based geopolymers. Feature engineering was constructed with molar ratios of raw material oxide composition, curing system, and mixing design. A total of eight algorithms in three types, traditional ML algorithms, integrated tree-based ML algorithms, and deep neural network algorithm, were employed to predict the compressive strength, and their differences, advantages, and disadvantages were compared. The importance of input variables in model training was evaluated. The contribution and influence pattern of input features on the development of compressive strength were revealed using the SHapley Additive exPlanations (SHAP) and inverse prediction. The results demonstrate that among the eight models proposed, the XGB model had the highest prediction accuracy (91%) and the lowest root mean squared error (3.85 MPa). Based on the importance analysis and the SHAP value, the parameters that had the greatest impact on the compressive strength were curing age, n(H2O)/n(Na2O), curing temperature, n(SiO2)/n(CaO) and the mass ratio of alkali activation solution to solid powder (L/S). The effects of input features on the compressive strength development of calcium-based geopolymers captured by SHAP and inverse predictions based on the best predictive model were consistent with the experimental results and theoretical understanding. The research in this paper facilitates the rapid prediction, improvement and optimization of the proportioning design and application of calcium-based geopolymers, and also provides a theoretical basis for the utilization of industrial and construction waste, in line with sustainable and low-carbon development strategies.

Performance Investigation of Geopolymer Grouting Material with Varied Mix Proportions

Grouting materials require not only high ultra-early-stage strength of the stone body, but also proper working performances, such as high fluidity and fast setting time, as well as good stability. Compared with the traditional pure cement grout, geopolymer grouting material has the advantages of fast setting time, high fluidity, good slurry stability, and high early strength of the slurry stone body, which is beneficial to reuse solid waste resources and can be applied to the conditions of rapid construction or repair work to a certain extent. This paper presents an experimental investigation into the performance variation of geopolymer grouting material with varied mass fractions of raw materials, and the grouting performance of geopolymer material with optimal mix proportion is also presented. The study is implemented by employing the designed experimental schemes, focused on fluidity and setting times, as well as ultra-early-stage (4 h, 8 h, 12 h, 16 h, 20 h, and 24 h) mechanical strength. The experimental result demonstrates that both ground granulated blast-furnace slag (GGBS) content and the mass ratio of activator solution to solid have influence on the working performance of geopolymers, and both GGBS content and activator concentration have influence on the mechanical strength of geopolymers. Furthermore, the variance analysis demonstrates that the fluidity of geopolymer material is dominantly affected by the mass ratio of activator solution to solid, the setting time of geopolymer material is mainly influenced by GGBS content, and the mechanical strength of geopolymer material is mainly affected by activator concentration. Moreover, the recommended mix proportion of geopolymer grouting material is proposed in this study, in which the replacement rate of GGBS is 45%; the modulus and concentration of modified sodium silicate activator are 1.5 and 75%, respectively; and the mass ratio of activator solution to solid is 1.5. In the recommended mix proportion, the geopolymer material has excellent comprehensive performance to implement grouting operation, in which the compressive and tensile strengths of the stone body reach 12.2 MPa and 0.8 MPa in 4 h, and reach 21.2 MPa and 2.1 MPa in 24 h. The fluidity is 223 mm, the initial setting and final setting times are 50 min and 57 min, the slurry stability of geopolymer material is good without liquid precipitation, in which the setting time is far less than 2 h. This work provides the experimental foundations for investigating the performance of geopolymer grouting material, which is also expected to provide reference for the further application and promotion of geopolymer materials used for grouting operations in rapid construction or repair work.

PREPARATION AND PROPERTIES OF AGGLOMERATED CORK PANELS BOUND WITH CHITOSAN BINDER

In this paper, acidified chitosan was used as an adhesive to prepare aldehyde-free, environmentally-friendly agglomerated cork panels by hot-pressing. After preparation, thephysical, mechanical, and the finishing properties of the chitosan-glued agglomerated cork panels were investigated. The optimal mass ratio of acetic acid solution (1wt.%) to chitosan was determined to be 30:1. The resulting hot-pressed agglomerated cork panels, which featured adensity of 0.55 g.cm-3and a thickness of 4 mm, exhibited a tensile strength of 1.70 MPa and athermal conductivity of 0.11W.m-1·K-1. The agglomerated cork panels coated with theoil-based polyurethane and water-based, acrylic-modified polyurethane paints exhibited significantly lower lightness and higher glossiness. The total color differences (ΔE*) ofboth agglomerated cork panels increased before and after finishing. The oil-based polyurethane paint coating exhibited high adhesion of paint film, reaching a level-0 adhesion, while thewater-based, acrylic-modified polyurethane paint coating achieved a level-1 adhesion. Theabrasion resistance results showed that the substrates of cork agglomerates coated two types of paint did not expose after undergoing abrasion for 100 revolutions atthe turntable speed of 60 rpm.

Self-Cleaning Coatings for the Protection of Cementitious Materials: The Effect of Carbon Dot Content on the Enhancement of Catalytic Activity of TiO2

The urgent demand for pollution protection of monuments and buildings forced the interest towards specific preservation methods, such as the application of photocatalytic coatings with self-cleaning and protective activity. TiO2 photocatalysts without and with a variety of carbon dots loading (TC0, TC25–75) were synthesized via a green, simple, low cost and large-scale hydrothermal method using citric acid, hydroxylamine and titanium isopropoxide (TTIP) and resulted in uniform anatase phase structures. In photocatalysis experiments, TC25 and TC50 composites with 1:3 and 1:1 mass ratio of C-dots solution to TTIP, respectively, showed the best degradation efficiency for methyl orange (MO) under UV-A light, simulated solar light and sunlight compared to TiO2, commercial Au/TiO2 (TAu) and catalysts with higher C-dot loading (TC62.5 and TC75). Treatment of cement mortars with a mixture of photocatalyst and a consolidant (FX-C) provided self-cleaning activity under UV-A and visible light. This study produced a variety of new, durable, heavy metal-free C-dots/TiO2 photocatalysts that operate well under outdoor weather conditions, evidencing the C-dot dosage-dependent performance. For the building protection against pollution, nanostructured photocatalytic films were proposed with consolidation and self-cleaning ability under solar irradiation, deriving from combined protective silica-based agents and TiO2 photocatalysts free or with low C-dot content.

Fabrication and characterization of chitosan nanoparticles using the coffee-ring effect for photodynamic therapy.

Biocompatible nanoparticles have been increasingly used in a variety of medical applications, including photodynamic therapy. Although the impact of synthesis parameters and purification methods is reported in previous studies, it is still challenging to produce a reliable protocol for the fabrication, purification, and characterization of nanoparticles in the 200-300 nm range that are highly monodisperse for biomedical applications. We investigated the synthesis of chitosan nanoparticles in the 200-300 nm range by evaluating the chitosan to sodium tripolyphosphate (TPP) mass ratio and acetic acid concentration of the chitosan solution. Chitosan nanoparticles were also crosslinked to rose bengal and incubated with human breast cancer cells (MCF-7) to test photodynamic activity using a green laser (λ = 532 nm, power = 90 mW). We established a simple protocol to fabricate and purify biocompatible nanoparticles with the most frequent size occurring between 200 and 300 nm. This was achieved using a chitosan to TPP mass ratio of 5:1 in 1% v/v acetic acid at a pH of 5.5. The protocol involved the formation of nanoparticle coffee rings that showed the particle shape to be spherical in the first approximation. Photodynamic treatment with rose bengal-nanoparticles killed ~98% of cancer cells. A simple protocol was established to prepare and purify spherical and biocompatible chitosan nanoparticles with a peak size of ~200 nm. These have remarkable antitumor activity when coupled with photodynamic treatment.

Rapid enzymatic hydrolysis of crambe oil catalyzed by castor seeds lipases

Oil hydrolysis is an important industrial process that requires high temperatures and pressure, or expensive enzymatic catalysts; it is, therefore, necessary to seek the use of inexpensive raw materials and process enhancement. In this work, a rapid and eco-friendly method, using ultrasound power, was successfully employed to hydrolyze crambe (Crambe abyssinica Hochst.) oil using lipase enzymes directly from castor (Ricinus communis L.) seeds, in oil-free and fresh forms. A yield of 86 % conversion of triglycerides into free fatty acids (FFA) was achieved in 5 min using castor fresh seeds and 73 % of conversion when performing the reaction with oil-free seeds. The operational conditions of ultrasound power, mass ratio of buffer solution and oil, catalyst, and total substrate were evaluated using a central composite rotatable design (CCRD). The hydrolysis yield was optimized by response surface methodology (RSM). The optimum conditions were approximately 70 % of ultrasound power (350 W), 1.79 buffer solution/oil mass ratio, and 0.25 catalyst/substrate mass ratio for fresh seeds. For the oil-free seeds, the optimal conditions found were 68 % (340 W) of ultrasound power, 1.67 buffer solution/oil mass ratio, and 0.06 catalyst/substrate mass ratio. Mathematical modeling was applied to the experimental kinetic data, and it was possible to predict FFA concentration values from independent experiments.

Construction of high-performance CeO2 ultrafiltration membrane for high-temperature dye/salt separation

CeO2 is an alternative membrane material for precise separation under harsh conditions because of its single fluorite structure and outstanding high-temperature stability. In this study, uniform and stable CeO2 colloidal sols were successfully prepared using an ultrasound-assisted precipitation method with an average particle size of approximately 5 nm. To prepare crack-free CeO2 membranes with a controllable thickness, concentration of polyvinyl alcohol in the colloidal sol and the coating time were investigated. An integrated membrane layer was fabricated by adjusting the sol to PVA solution mass ratio to 1:1 with a coating time of 30 s. After calcination at 500 °C, a thin CeO2 membrane (approximately 200 nm thick) was obtained. In addition, the CeO2 material derived from the as-prepared sol showed a fluorite structure and lattice fringes corresponding to different crystal planes, indicating the formation of a pure CeO2 thin membrane. The CeO2 membrane exhibited a high performance, with a molecular weight cut-off of 3.9 kDa and a high water permeance of 100 L m−2 h−1·bar−1. It showed excellent thermal stability, promising good potential applicability at high temperatures. Additionally, it exhibited the dye rejection rates of >99% for Direct Red 80 and 95.5% for Congo Red, and salt rejection rates of <1% at 60 °C in the simulated dye wastewater treatment. Overall, this study presents a new tight ultrafiltration membrane material that has good potential for high-temperature dye wastewater treatment.

Modeling of liquid fuel purification by the LTA zeolite using machine learning methods

Impurities have severe negative influences on both the application and energy content of the dimethyl aminoethyl azide (DMAZ) fuel. Therefore, it is necessary to dehydrate the DMAZ liquid fuel using an appropriate separation scenario. This separation is often performed through an adsorption process employing the LTA zeolite (Linde type A). Hence, this study aims to employ different artificial intelligence techniques to simulate the performance of LTA zeolite for dehydration of DMAZ liquid fuel. Initial water concentration, contact time, temperature, and zeolite per solution (DMAZ + water) mass ratio are those features utilized to estimate zeolite capacity for water adsorption. Systematic ranking analyses applied on several statistical criteria approved that the generalized regression neural network is the best smart model for the considered matter. The proposed generalized regression approach predicted a big reliable experimental database with the AARD = 5.68%, RMSE = 11.26, MAE = 6.97%, and R2 = 0.9675. The influence of different operating conditions on the performance of zeolite adsorption capacity (ZAC) is investigated both experimentally and by using the generalized regression approach. Modeling results justified that the maximum water removal per unit mass of the LTA zeolite is about 0.202 in the optimum conditions.

Soil Conditioning Tests on Sandy and Cobbly Soil for Shield Tunneling

Soil conditioning is an important stage in shield tunnel construction that can effectively improve muck flow plasticity, reduce cutter head wear and improve tunneling efficiency, especially in sandy and cobbly soils. The aim of this paper is to obtain the optimal ratio of residue modifiers in sandy and cobbly soil and to improve the equipment used in residue-related shield machines. Residual soil in a sandy pebble layer was selected, and particles with sizes over 50 mm were removed to form soil samples. Through laboratory tests, the optimal ratio of the modifier was obtained, and the shield tunneling machine equipment was optimized. The research results for the laboratory tests and equipment optimization were verified and adjusted appropriately through field tunneling tests. The following results were obtained. 1) A 3% foaming agent C was selected for the soil conditioning tests. The final mass ratio of the bentonite mixed solution of water, bentonite, soda ash (Na2CO3), and carboxymethyl cellulose (CMC) was 6:1:0.028:0.035. 2) Improving earth pressure balance (EPB) shield machine equipment can improve the effects of soil conditioning. 3) Compared with the volume of residual soil, the optimal ratio of soil conditioning in sandy and cobbly layer was 13% water, 4–5% bentonite mixed solution and 12–15% foam. In addition, the maximum ratio shall be taken for the strata with poor grain composition. These results can be used to provide excavation guidelines for using an EPB machine under these soil conditions.

Hydrogel-Based Transparent Subdural Electrode with Salt Bridge As Interface to Brain Surface

Intraoperative biomedical devices are used in many medical fields such as monitoring, diagnosis and treatment of diseases. Subdural electrodes used in monitoring cortical activity contribute to an identification of pathological lesions in an epilepsy surgery and also the advance of elucidation of brain function. These electrodes as an interface with living systems should be flexible, biocompatible, and conformable to the curved brain surface. However, conventional electrodes consisting of metals such as Pt electrodes and a silicone-based substrate have not fully resolved mismatches between electronics circuit of a machine and biological wet systems, which causes a decrease of measurement accuracy and damage to bio-tissue[1]. In a previous study, we have developed a totally organic hydrogel-based subdural electrode by embedding a carbon fabric (CF) modified with poly(3,4-ethylenedioxythiophene) (PEDOT) into a poly(vinyl alcohol) (PVA) hydrogel substrate[2]. This wet electrode showed a good softness similar to the living tissue, a high conformability to a curved surface such as brains, and easy handling. Moreover, the totally organic nature would contribute to obtain clear MRI images without image artifacts.In this study, we have developed a new type of the hydrogel-based transparent subdural electrode in which the salt bridge acts as interface to bio-tissue (Fig. 1A). The present electrode consisted of three different parts, a salt bridge made of PVA hydrogel insulated by the microchannel made of Poly(dimethylpolysiloxane) (PDMS) membrane embedded into the PVA hydrogel substrate. The unique feature of the hydrogel-based electrode with the salt bridge system was aqueous-based interface to bio-tissue on which can be decreased an effect of the electrochemical reaction. The aqueous-based electrode similar to bio-tissue enable to be flexible, biocompatible, and conformable due to the use of highly soft and wet biomaterial. In addition, the device has an optical transparency which can contribute to obtaining detailed visual information under the electrode during surgical operations and would be valuable to the neuroscience in optogenetics.The PDMS membrane-based channel (thickness: 600 µm, width: 500 µm, height 100 µm) was fabricated by spin-coating at 700 rpm for 15 seconds on the SU-8 mold and bonding with an oxygen plasma treatment. PVA (Mw~145000) hydrogels for both a salt bridge (10 wt%) and substrate (15 wt%) were dissolved in a mixture of dimethyl sulfoxide (DMSO) and saturated KCl solution (mass ratio = 4:1). The PDMS membrane-based channel connected to the silicone tube for extension was filled with PVA hydrogel as a salt bridge, sandwiched by glass slides with 1.5 mm-thickness spacer which was filled with the PVA hydrogel, and crosslinked by freeze-thaw cycles (as -30 °C for 10 min and 4 °C for 10 min, each repeated three times). The fabricated electrode was rinsed twice in Ringer’s solution for one hour and overnight. The conformability was evaluated by the rate of contact area between electrodes and the surface of the curved sheet with various curvatures. In vivo recording was conducted on a porcine which was anaesthetized with the head fixed in a stereotaxic apparatus, and the dura mater was partially removed by a neurosurgeon to expose the surface of the cerebral cortex. Then, electrodes were placed on the exposed cortex on each hemisphere for simultaneous electrocorticography (ECoG) recording (2019MdA-324).Figure 1B shows the conformability of the developed and conventional electrode to the curved surface. The contact area of the hydrogel electrode showed more than 80 %, which was higher conformable than that of the silicone-based conventional electrode (~ 50 %). Figure 1C shows that the hydrogel electrode consisting of PVA hydrogels and PDMS as a highly transparent and biocompatible material, showed a sufficiently transparent to recognize the condition under the device. In contrast, the commercially available electrode was opaque due to thick silicone-based substrate and metal. As shown in Figure 1D, we successfully measured brain waves by the hydrogel electrode with the salt bridge system in vivo measurements on porcine. From this result, the salt bridge acted as the resistance for ionical connection and ionically connected from bio-tissue to electronic measurement machine. We successfully developed a new hydrogel-based transparent subdural electrode with the salt bridge as a bio-friendly interface.

Physical appearance and arsenate removal efficiency of Fe(III)-modified clinoptilolite beads affected by alginate-wet-granulation process parameters

Fe(III)-modified clinoptilolite (Fe-Clin) was encapsulated into beads using sodium alginate (NaAlg) and Ca2+ and/or Fe3+ ions by a simple wet-gelation method to obtain Fe-Clin beads. The impacts of various parameters including mixture pH, type of cross-linker, concentration of cross-linking solution and initial mass ratio of NaAlg to Fe-Clin were investigated on the appearance of beads and also their performance in As(V) removal. To increase the net negative surface charge of alginate, pH value of the mixture was essentially adjusted to the level 12–13. This strong alkaline condition increased the ability of alginate mixture to form stable and well-shaped beads. Ca2+ acting as a cross-linker showed a less impact on the beads shape than Fe3+ due to the strong tendency of Fe3+ ions to react with oxygen atoms in carboxylate groups of alginate. A loosely cross-linked Ca2+-alginate network formed during preparation of Fe-Clin beads was considered as the main reason for their lower arsenate removal efficiency of 29.4% rather than 60.5% for those cross-linked in FeCl3. In addition, there were found optimal values of FeCl3 cross-linking solution concentration and initial mass ratio of NaAlg: Fe-Clin as 2% (w/v) and 1:4, respectively to achieve the maximum As(V) removal efficiency of 82%.

Assessment of sulfamethoxazole removal by nanoscale zerovalent iron

Removal of pharmaceutical compounds, such as sulfamethoxazole (SMX) from the aquatic environments, is critical in order to mitigate their adverse environmental and human health effects. In this study, the effectiveness of nanoscale zerovalent iron (nZVI) particles for the removal of SMX was investigated under varying conditions of initial solution pH (3, 5, 7 and 11) and nZVI to SMX mass ratios (1:1, 5:1, 10:1, 13:1, 25:1). Batch kinetic studies, which were well represented using both pseudo-first-order and pseudo-second-order kinetic models (R2 > 0.98), showed that both solution pH and mass ratios strongly influenced SMX removal. At a fixed mass ratio of 10:1, removal efficiencies were higher in acidic conditions (83% to 91%) compared to neutral (29%) and alkaline (6%) conditions. A similar trend was observed for removal rates and removal amounts. For mass ratios between 1:1 and 10:1, an optimum pH existed (pH 5) wherein highest removal efficiencies were attained. Increasing the mass ratio above 10:1 resulted in virtually complete removal efficiencies at pH 3 and 5, and 70% at pH 7. Analysis of SMX speciation and zeta potential of nZVI particles provided insights into the role of pH on the efficiencies, rates and extents of SMX removal. Total organic carbon analysis and mass spectrometry measurements of SMX solution before and after exposure to nZVI particles suggested the transformation of SMX via redox reactions, which are likely the dominant process compared to adsorption. Five transformation products were observed at m/z 156 (TP1), 192 (TP2), 256 (TP3), 294 (TP4) and 296 (TP5). TP1, TP2 and TP3 were further identified using ion fragment analysis. Overall, results from this study indicate a strong potential for SMX removal by nZVI particles, and could be useful towards identifying reaction conditions for optimum SMX transformation.

Secado solar de berenjenas impregnadas con Ca y Zn

La berenjena (Solanum melongena L.) posee componentes bioactivos beneficiosos para la salud. El objetivo del trabajo fue obtener berenjenas deshidratadas con alto valor nutricional y excelente capacidad de rehidratación. Las berenjenas se cortaron en rodajas de 5 mm, se deshidrataron en un secadero solar, algunas de ellas se sometieron a un pretratamiento de deshidratación osmótica/impregnación (DO/I) para fortificarlas con calcio y zinc y otras no para poder comparar posteriormente su calidad estructural y nutricional. La solución deshidratante consistió en 40% m/m sacarosa, 5% m/m cloruro de calcio, 5% m/m ácido ascórbico y 1% m/m ácido cítrico (55° Brix) a una temperatura de 40°C. Se empleó una relación masa de solución a masa de berenjenas de 4 y un nivel de agitación de 120 rpm.Durante el secado se tomaron muestras para determinar el contenido de calcio y zinc por espectrofotometría de absorción atómica, la humedad, la pérdida de peso y, el color. Asimismo, se modeló la cinetica de secado y la posterior rehidratación.Luego del secado solar por 6 h, las berenjenas sin DO/I alcanzaron una concentración de 600 mg Ca/kg mientras que las pretratadas, un valor de 18000mg Ca/kg. Las berenjenas frescas presentan un rango de humedad de 91-94% en base húmeda, luego de un pretratamiento por (DO/I) de 1h se alcanza un valor de 64-67% (bh) y el posterior secado solar por 7h logra un valor de 30-21%. Con secado solar sin pretratamiento de 7h, se obtuvo una humedad 66- 63% (bh). El producto pretratado presentó menor luminosidad L*: 49,7 ± 0,7 respecto del sin pretratar L*: 71,7 ± 3,1, valores de a* superiores con una diferencia del 50% y valores de b* bastante similares. Para modelar la cinetica de secado se usó el modelo Page y Crank, Los parámetros del modelo de Page obtenidos fueron: C: 1±0,25; K: 0,078±0,004 y n: 1,7±0,3 para un ajuste (R2: 0,995), para las muestras que se sometieron a pretratamiento por deshidratación osmótica y C: 2,65±0,50; K: 0,0047±0,00024, n: 2,75±0,48 (R2: 0.998) para las restantes. El coeficiente de difusión efectivo obtenido por el modelo de Crank fue de 2,44 ± 0,33. 10 -10 m2 /s y de 1,87 ± 0,25. 10 -10 m2 /s para las muestras con y sin pretratamiento por deshidratación osmótica, respectivamente. La rehidratación fue mejor en la berenjena pretratada. Al cabo de 4h de rehidratación a 20°C, se alcanzó una humedad de 89% (b.h). Este fenómeno evidenció que la deshidratación osmótica/impregnación logra preservar la estructura del alimento.