Search

This study investigated cellobionate production from a lignocellulosic substrate using Neurospora crassa HL10. Utilizing NaOH-pretreated wheat straw as the substrate obviated the need for an exogenous redox mediator addition, as lignin contained in the pretreated wheat served as a natural mediator. The low laccase production by N. crassa HL10 on pretreated wheat straw caused slow cellobionate production, and exogenous laccase addition accelerated the process. Cycloheximide induced substantial laccase production in N. crassa HL10, enabling the strain to yield approximately 57 mM cellobionate from pretreated wheat straw (equivalent to 20 g/L cellulose), shortening the conversion time from 8 to 6 days. About 92% of the cellulose contained in the pretreated wheat straw is converted to cellobionate. In contrast to existing methods requiring pure cellobiose or cellulase enzymes, this process efficiently converts a low-cost feedstock into cellobionate at a high yield without enzyme or redox mediator supplementation.

Volcanic ash was used as a precursor for the synthesis of a geopolymer activated by sodium hydroxide and using hydrogen peroxide as a pore-forming agent. Factors controlling geopolymer synthesis such as sodium hydroxide concentration (6–12 mol/L), liquid/solid mass ratio (0.3–0.5), and H2O2 mass concentration (0%–2%) were optimized using the Box-Behnken design method. The chosen process variables were optimized to enhance both the geopolymer's porosity and its effectiveness in removing crystal violet. Sodium hydroxide concentration and H2O2 mass concentration had a significant effect on both responses. Under optimal conditions of 6 mol/L NaOH concentration, a 0.3 liquid/solid ratio, and 2% H2O2 mass concentration, the model-predicted and experimental values for both responses were highly comparable. Additionally, response surface methodology was used to assess the removal of crystal violet from an aqueous solution, employing the geopolymer produced under these optimal conditions as the adsorbent. Experiments were carried out according to the Box-Behnken statistical surface design with four input parameters, namely, contact time (A: 10–120 min), initial crystal violet concentration (B: 20–100 mg/L), adsorbent dose (C: 0.1–0.6 g), and pH (D: 3–9). Regression analysis indicated a strong fit of the experimental data to the second-order polynomial model, with a coefficient of determination (R2) of 0.9864 and a Fisher's F value of 61.97. Optimization of the parameters A (35.415 mg/L), B (98.184 min), C (0.359 g), and pH (6.950) achieved a maximum crystal violet removal of 98.413% by the geopolymer. [ABSTRACT FROM AUTHOR]

This article systematically investigated the improvement effect of polypropylene fiber (PPF) on the mechanical and freeze–thaw properties of alkali-activated fly ash slag concrete (AAFSC) with high fly ash content and cured at room temperature. Fly ash and slag were used as precursors, with fly ash accounting for 80% of the total mass. A mixed solution of sodium hydroxide and sodium silicate was used as alkali activator, and short-cut PPF was added to improve the performance of AAFSC. Firstly, the strength characteristics of AAFSC at different curing ages were studied. Then, key indicators such as morphology, residual compressive strength, weight loss, relative dynamic modulus of elasticity (RDME), and pore characteristics of AAFSC after different freeze–thaw cycles were tested and analyzed. The strength performance analysis showed that the optimal dosage of PPF was 0.90%. When the alkali equivalent of the alkali activator was increased from 4% to 6%, the frost resistance of AAFSC could be improved. Furthermore, adding 0.90% PPF could increase the freeze–thaw cycle number of AAFSC by about 50 times (measured by RDME). With the increase in freeze–thaw cycles, the porosity of AAFSC increased, the fractal dimension decreased, and the proportion of harmless and less harmful pores decreased, while the proportion of harmful and multiple harmful pores increased. The relationship model between the porosity and compressive strength of AAFSC after freeze–thaw cycles was established. [ABSTRACT FROM AUTHOR]

High-strength carbon fibers were recovered by a new method, involving the decomposition of the thermosetting resin part of carbon fiber-reinforced plastic (CFRP) by heating it in a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Alkali molten hydroxide was prepared by heating the mixture of NaOH and KOH at various ratios (NaOH: KOH = 1:0, 3:1, 1:1, 1:3, 0:1) at 400oC, and the CFRP was then heated with the aforementioned alkali molten hydroxide under a nitrogen atmosphere at 200–400oC for 0–90 min. Subsequently, the CFRP was washed with distilled water and filtered to recover the carbon fibers, and its tensile strength was estimated. Carbon fibers with higher strength can be recovered by heating the CFRP with an alkali molten hydroxide. As the temperature increased, the strength of the recovered carbon fiber decreased owing to the increase in gas generation caused by the decomposition of the thermosetting resin and carbon fiber in the molten hydroxide, such as H2 and CH4. KOH increase in the alkali molten hydroxide promoted decomposition of the resin, whereas the fiber was degraded. High-strength carbon fiber, nearly the same as virgin fiber, can be recovered at 200oC using the NaOH: KOH molten hydroxide at a ratio of 1:3. [ABSTRACT FROM AUTHOR]

This study comprises two distinct but interrelated parts. The first part involves optimizing the conditions for the conversion of phosphogypsum to a Ca(OH)2 and Na2SO4 solution. The second part focuses on enhancing the mechanical properties of gypsum through the use of a sodium sulphate additive derived from the conversion of phosphogypsum. An ultrasonic disperser was employed to accelerate the reaction between phosphogypsum and a sodium hydroxide solution. The mean dispersion time was found to be 0.2, 0.5, 1.0, and 2.0 min. The resulting product was a solution of calcium hydroxide and sodium sulfate. The impact of varying quantities of Na2SO4 on the compressive strength and density of building gypsum samples was investigated. An increase in the quantity of sodium sulphate from 0.2% to 2% resulted in a notable rise in the density of the building gypsum samples, from 1127 kg/m3 in the reference sample to 1264 kg/m3 in the sample containing 2% sodium sulphate. Therefore, in all instances, the utilization of the Na2SO4 additive in the gypsum samples resulted in elevated compressive strengths (4.8–8.6 MPa) in comparison to the reference sample devoid of this additive (1.6 MPa). [ABSTRACT FROM AUTHOR]

Air pollution caused by sulphur dioxide (SO2) emissions is pervasive and has severe health and environmental consequences. In recent years, global SO2 emissions have decreased dramatically due to the widespread adoption of cleaner technologies and stricter emission regulations. The availabilities of highly concentrated SO2 separation prompted this study's focus on reducing SO2 emissions, particularly for low-concentrated SO2 (100 ppm), employing ferric oxide nanoparticles. Upon thermal degradation of the adsorptive ferric oxide, both functional Fe–O and ferric oxide were observed. A 3:1 mixture of sodium hydroxide and ethanol was used to chemically activate the surface of the adsorbent, increasing both the pH and surface area from 6.5 to 10 and 183 to 531 m2 g−1, respectively. Maximum adsorption capacity (477.5 mg g−1) and maximum adsorption percentage (97.89%) were highest for the lowest SO2 concentration (56 mg m−3) compared to the other two SO2 concentrations (65 and 73 mg m−3). The Freundlich isotherm outperforms the other four models with the highest correlation coefficient (R2 = 0.9897). SO2 adsorption was physisorption, as the thermodynamic values, change of enthalpy and free energy decreased from −902 to −2052 kJ mol−1 and −243 to −562 kJ mol−1 as the temperature of the adsorption process ascended from room temperature to 70 °C. The SO2 was successfully removed from the adsorbent using temperature-programmed desorption analysis, with a maximal discharge of 1681 mg m−3 of SO2 and enhanced ferric oxide. Effective SO2 adsorption by the adsorbent for up to four cycles suggests that SO2 capture costs could be decreased. [ABSTRACT FROM AUTHOR]

Dechlorination is a crucial strategy for archeological bronze stabilization to resist corrosion induced by cuprous chloride (CuCl). Conventional samples, either archeological or simulated ones, have deficiencies in revealing dechlorination mechanisms for their complex rust layers and difficulties in quantifying chlorine content. In this work, samples with fixed chlorine amounts were prepared by compressing method to solve overcomplicated and unquantifiable problems. Then, patina profiles and desalinization solutions were analyzed to revisit the dechlorination mechanism across varying solution concentrations and current densities after dechlorination treatments. Results indicate that the sodium hydroxide (NaOH) desalinization method is achieved by converting CuCl to trihydroxychloride (Cu2(OH)3Cl). However, this transformation leads to an expansion of the CuCl layer, nearly doubling the CuCl layer thickness at the current density of 25 μA/cm2. Dechlorination solution measurements provide information on quantifying chlorine removal and dechlorination progress. Theoretically, the endpoint (c0) for the NaOH dechlorination method is supposed to be a chloride ion concentration of 358.2 ppm. As the NaOH solution concentrations vary from 10−6 to 10−2, CuCl dechlorination progress (Et=24h) calculations are at about 3% to 6% at 24 h. Applying the current significantly improves the effectiveness of dechlorination at 2.5 μA/cm2. However, the chloride ion concentration in the solution starts to decrease after reaching a current density of 12.5 μA/cm2, even dropping to 12.07 ppm at 25 μA/cm2. According to a theoretical analysis, chlorine evolution during electrolytic processes would be responsible for this phenomenon. [ABSTRACT FROM AUTHOR]

Recycling the metals found in spent batteries offers both environmental and economic benefits, especially when extracted and purified using environmentally friendly processes. Two basic leaching agents were tested and compared: ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH). Using NH4OH 4 M at 25 °C, 30.5 ± 0.7 wt. % of zinc (Zn) was dissolved for a solid/liquid (S/L) ratio of 1/10 (g of black mass (BM)/mL of solution); meanwhile, with NaOH 6 M at 70 °C, and an S/L ratio of 1/5 (g of BM/mL of solution), 69.9 ± 2.8 wt. % of the Zn initially present in the BM of alkaline batteries was leached. A virtual representation of the experimental data through digital twins of the alkaline leaching process of the BM was proposed. For this purpose, 90% of the experimental data were used for training a supervised learning procedure involving 600 different artificial neural networks (ANNs) and using up to 12 activation functions. The application was able to choose the most suitable ANN using an ANOVA analysis. After the training step, the network was tested by predicting the outputs of inputs that were not used in the training process, to avoid overfitting in a validating process with 10% of the data. The best model was employed for estimating the degree of leaching of different metals that can be obtained from BM, obtaining a data deviation of less than 10% for highly concentrated compounds such as Zn. [ABSTRACT FROM AUTHOR]

Backfill materials are used in underground engineering to fill voids and buried excavated parts. In this study, solid waste was utilised as a raw material mixed with different amounts of polypropylene fibres to determine the optimal sodium hydroxide content, water—solid ratio, and fibre content. The uniaxial compressive strength (UCS) of the produced backfill materials was measured, and the interfacial structures were analysed via scanning electron microscopy. The results revealed that the mechanical properties of the backfill materials were influenced in the order sodium hydroxide doping > water—solid ratio > fibre doping. The optimal material composition corresponded to a sodium hydroxide content of 3%, water—solid ratio of 0.28, and fibre content of 5 ‰. The slag produced a C—S–H gel. Meanwhile, the fly ash and gangue contained large amounts of aluminium, which formed hydrated aluminosilicates. The addition of polypropylene fibres reduced the number of internal defects in the backfill structure and increased the UCS. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a versatile biopolymer with significant potential across biomedical, food, and industrial applications. To remove bacterial contaminants, such as protein and DNA, BC pellicles undergo purification, which traditionally relies on harsh alkali treatments, such as sodium hydroxide or strong surfactants, which present environmental concerns. In response, this study evaluates the efficacy of various non-conventional surfactants—both non-biodegradable and biodegradable—as alternatives for BC purification. Among the surfactants tested, sodium cocoyl isethionate (SCI), a mild anionic and biodegradable surfactant, emerged as particularly effective, achieving an 80.7% reduction in protein content and a 65.19% reduction in double-stranded DNA (dsDNA) content relative to untreated samples. However, these advantages were not without additional challenges, such as the appearance of residual surfactants. Given SCI's promising performance and biodegradability, it was further examined in two-step treatment protocols; additionally, sodium dodecyl sulfate (SDS) was also examined as a more traditional anionic surfactant as well as NaOH. For the two-step treatment protocol, BC pellicles were treated with one reagent for 3 h, followed by a second reagent for an additional 3 h. Notably, by using NaOH as the final step in the two-step treatment protocol, residual surfactant was not detected in the FTIR analysis. Overall, this work demonstrates that SCI, in addition to subsequent NaOH treatment, can be used as a surfactant-based approach for BC purification, representing a potential environmentally friendly alternative to traditional surfactant-based approaches for BC purification. [ABSTRACT FROM AUTHOR]

Mild conditioned, second-life ternary nickel–cobalt–manganese (NCM) black powder regeneration from spent lithium-ion batteries' (LIBs) black powder mixture was demonstrated after mild conditioned p-toluenesulphuric acid (PTA)-assisted wet leaching. The NCM ratio was tailored to several combinations (333, 523, 532, and 622) by adding a suitable amount of metal (Ni, Co, Mn)-sulphate salt to the leachate. Regenerated NCM was obtained by co-precipitation with sodium hydroxide pellets and ammonia pH buffering solution, followed by lithium (Li) sintering under ambient air and size sieving. The obtained regenerated NCM powder was used for the energy storage materials (ESM) in coin cell (Li half-cell, CR2032) evaluation. Systematic characterization of regenerated NCM showed that the NCM ratio was close to the target value as assigned in the tailored process, and regenerated 622 (R622) exhibited strong activity in CR2032 coin cell testing among all four ratios with a maximum discharge capacity of 196.6 mAh/g. [ABSTRACT FROM AUTHOR]

This paper studies the extraction of alumina from kaolin through an acidic leaching process. The kaolin sample used in this study was taken from the Zonuz kaolin mine (Iran Porcelain Industries Company) at particle sizes smaller than 150 microns. Calcination of the kaolin sample was conducted at 700 ºC for 2 hours. Aluminum was leached from calcined kaolin with an H2SO4 acid solution. Temperature and time of leaching, acid concentration, and liquid-to-solid ratio were investigated as leaching parameters. The optimal leaching conditions were considered at 90 °C, 3 hours duration, 2.5 M acid concentration, 7 ml/g liquid-to-solid ratio, and 600 rpm stirring speed, and under these conditions, aluminum leaching recovery was obtained at 94.87%. To remove the iron impurity that is transferred to the solution during leaching, the pregnant leaching solution was purified. Purification was done by solvent extraction with an organic phase containing D2EHPA as an extractant and oil as a diluent, iron removal was achieved at 88.71%. By precipitating the aluminum hydroxide from a solution of aluminum sulfate with sodium hydroxide followed by calcination of the produced aluminum hydroxide at a temperature of 1200 °C for 2 hours, alumina with a purity of 97% was produced. The total recovery of alumina obtained from the studied kaolin under optimal conditions was 89.46%, which is desirable. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC-Co) with a cobalt binder has been widely used in industrial application. Through their high wear resistance and hardness, which make it a challenge to machine. Electrochemical discharge machining (ECDM) is a newly developed hybrid technique used to machine conductive and nonconductive materials. Tungsten carbide machining is an area that needs more investigation. In this study, different types of electrolytes have been tested in the electrochemical machining of tungsten carbide. It has been concluded that tungsten carbide was successfully machined with electrolytes that were either neutral salts or a combination of neutral salts and hydroxides, the highest material removal rate achieved was (0.09250 g/min), and the average surface roughness achieved in this work was measured at (Ra 0.9275 µm). However, deposition took place on the surface of machined tungsten carbide when the samples were treated with sodium hydroxide and potassium hydroxide. EDX analysis of successfully machined tungsten carbide samples reveal the presence of carbon (C) due to diffusion from the base material and oxygen (O), most likely due to oxidation brought on by the high temperatures utilized. Scanning electron microscopy confirmed that the machined surfaces had craters, pores, restricted microcracks, and re-deposited melt particles, among other things. [ABSTRACT FROM AUTHOR]

Abstract In this study, several methods for a novel binderless technology were explored, the effects of treatment conditions on the adhesive performance were examined and the surface was characterized during adhesion. The method entailed a three-step process for bonding solid wood, which involved immersion in sodium hypochlorite–containing treatment solutions, surface scratching, and drying with pressing. Various treatment conditions were investigated, including solution types, immersion durations, scratch treatment materials, and pressing methods. The resulting shear strength was 9.7 MPa, which is well above the Japanese Agricultural Standards value for laminated wood (6 MPa). In this method, the specimens were immersed in a bleach solution containing a surfactant for 16 h, followed by pressurization at 1 MPa for 24 h at 60 ℃ using a pressure-controlled press. Around the bonding area in the specimens, the cells in the immersed area were significantly compressed, and the aldehyde groups of the coniferyl aldehyde in the lignin were denatured or lost. Based on these findings, a new binderless technology was developed for solid wood without a high-temperature, high-pressure pressing step.

Mild steel corrosion adversely impacts various industries, specially in acidic environments, leading to reduced metal efficiency. This study explored the efficacy of mango leaves crude ethanolic extract (MLCEE) as a natural corrosion inhibitor for mild steel. Different concentrations, such as treatment 1 (25%), treatment 2 (50%), treatment 3 (75%), and treatment 4 (100%) MLCEE, were tested, along with a commercial inhibitor (WD-40). The dilution method was utilized to obtain the concentrations and acid/base solutions. The mild steel plate was cut and pre-treated through rapid thermal annealing. The mild steel was then immersed in 1M HCl and 1M NaOH for its corrosion test. Gravimetric weight loss was computed and statistically analyzed using one-way ANOVA and Tukey's HSD Test to determine the treatments’ effectiveness, revealing that the 100% concentration significantly differed from other treatments in both mediums, where it had a p-value of 0.00. Treatment 4 yielded no significant change in the weight of mild steel before (5.05 g) and after (5.01 g) immersion in HCl, and in weight before (4.65 g) and after (4.61 g) immersion in NaOH, as shown in the paired sample ttest, thus it indicates its potential as a metal coating against corrosion activity. This implied that MLCEE is capable of inhibiting corrosion inhibition and can withstand aggressive media. These results may become a basis for future studies covering metal corrosion and plant extract utilization. However, different annealing processes may be considered to promote better adsorption, and other parameters may be added to further explore the efficacy of MLCEE as a potential corrosion inhibitor.

Patient: Male, 23-year-old Final Diagnosis: Mycobacterium marinum infection Symptoms: Multiple sporotrichoid skin lesions Clinical Procedure: -- Specialty: Infectious Diseases Objective: Unknown etiology Background: Mycobacterium marinum is a slow-growing non-tuberculous mycobacterium that is known to cause skin and soft tissue infections, even in healthy patients, and is commonly associated with fish and aquatic environments. Case Report: A 23-year-old man working in aquarium management presented with a chronic progression of multiple skin nodules on his right forearm and thumb. The patient was referred from the Dermatology Department to the Outpatient Clinic due to suspected skin tuberculosis, as indicated by a positive T-SPOT.TB test. A second excisional biopsy tested positive for M. marinum via PCR sequencing by the National Institute of Infectious Diseases, confirming the diagnosis. The initial treatment consisted of rifabutin at 300 mg/day and clarithromycin at 800 mg/day. However, due to liver dysfunction, the regimen was changed to moxifloxacin at 400 mg/day and rifabutin. Moxifloxacin was discontinued due to nausea. Finally, the treatment was adjusted to linezolid at 1200 mg/day and clarithromycin. The patient's skin condition improved, with the nodular lesions showing a trend toward resolution. Culturing is time-consuming, and the sensitivity can be reduced when using N-acetyl-l-cysteine--sodium hydroxide in the pre-treatment process; therefore, caution with its use is necessary. Pathological examination can initially show inflammatory changes, and granulomatous lesions with caseous necrosis are not always present. Antibiotics such as rifampicin, rifabutin, moxifloxacin, and clarithromycin are used, but there is scant evidence for treatment regimens, often resulting in prolonged monotherapy or combination therapy. Conclusions: In cases presenting chronic lesions resembling multiple sporotrichoid forms, repeated biopsies are crucial due to the challenges associated with culturing. [ABSTRACT FROM AUTHOR]

Cement Asphalt Mortar (CAM) is widely applied in infrastructure, particularly in railways, bridge expansion joints, and pavements, due to its combination of cement's load-bearing capacity and asphalt's flexibility. Conventional CAM formulations, however, often encounter challenges such as extended setting times, high shrinkage, and limited durability under extreme environmental conditions. This study addresses these limitations by integrating bio-oil and polymer additives to enhance both the sustainability and performance of CAM mixtures. CAM mixtures were evaluated with cement-to-asphalt emulsion (C/AE) mass ratios of 75:25 and 50:50, incorporating bio-oil contents of 2% and 4% by mass and latex–acrylic polymer proportions ranging from 1% to 2% by mass. The optimized mix design, with a 75:25 cement-to-asphalt emulsion (C/AE) mass ratio, 2% bio-oil, and 1.5% polymer, improved flowability by 25%. This formulation achieved a flow diameter of approximately 205 mm and reduced the flow time to 72 s. Compressive strength tests indicated that this formulation reached an early-stage strength of 10.45 MPa (a 20.8% improvement over the control) and a 28-day strength of 24.18 MPa. Thermal stability tests at 45 °C demonstrated that the optimized CAM retained 86.6% of its compressive strength, compared to a 25% reduction in unmodified mixtures. Chemical resistance assessments in 5% sulfuric acid and 5% sodium hydroxide solutions showed strength retention of 95.03% and 91.98%, respectively, outperforming control mixtures by 17% and 13%. SEM examination revealed a dense, cohesive microstructure, reducing shrinkage to 0.01% from 0.15% in the control. These findings underscore the potential of bio-oil and latex–acrylic polymers to improve the performance and sustainability of CAM mixtures, making them well suited for resilient, rapid-setting infrastructure applications. [ABSTRACT FROM AUTHOR]

In this study, several methods for a novel binderless technology were explored, the effects of treatment conditions on the adhesive performance were examined and the surface was characterized during adhesion. The method entailed a three-step process for bonding solid wood, which involved immersion in sodium hypochlorite–containing treatment solutions, surface scratching, and drying with pressing. Various treatment conditions were investigated, including solution types, immersion durations, scratch treatment materials, and pressing methods. The resulting shear strength was 9.7 MPa, which is well above the Japanese Agricultural Standards value for laminated wood (6 MPa). In this method, the specimens were immersed in a bleach solution containing a surfactant for 16 h, followed by pressurization at 1 MPa for 24 h at 60 ℃ using a pressure-controlled press. Around the bonding area in the specimens, the cells in the immersed area were significantly compressed, and the aldehyde groups of the coniferyl aldehyde in the lignin were denatured or lost. Based on these findings, a new binderless technology was developed for solid wood without a high-temperature, high-pressure pressing step. [ABSTRACT FROM AUTHOR]

This research focuses on the feasibility of sustainable biocomposites for thermal insulation created from corn starch and reinforced with jute spinning mill waste, specifically evaluating the effect of caustic soda (NaOH) treatment on the quality of biocomposite materials. Here, the jute fibers used were not clean because these fibers were collected from jute fibers waste. So it was necessary to clean the fibers and 15% (w/w) caustic soda (NaOH) showed more cleaning efficiency than 5%, 10%, and 20% (w/w) NaOH solution. After that, the composite material was made from caustic soda–treated and caustic soda–nontreated jute fibers. Then, the physical properties of composite materials were checked comparing with insulation foam for identifying the thermal insulation properties. Tensile strength, shore hardness, density, water absorption, and thermal conductivity were among the key performance indicators evaluated. The tensile strength, flexural strength, shore hardness, density, water absorption, thermal conductivity, SEM view, and surface smoothness were checked for 15% NaOH‐treated and NaOH‐untreated jute fibers and make compression with insulation foam to detect the thermal insulation of the biocomposite. Here, 15% caustic‐treated sample showed good results than the untreated sample. Overall, integrating caustic‐treated jute waste into corn starch‐based composites is a realistic and ecologically suitable alternative to typical thermal insulating materials, with higher mechanical properties, adequate thermal performance as well as being beneficial to the environment. [ABSTRACT FROM AUTHOR]

Stable electrospray generation from fused silica tips is critical for mass spectrometry, but these tips can degrade, leading to droplet formation and poor spray. A quick, cost-effective method has been developed to rejuvenate these tips, extending their usability and reducing expenses. The protocol involves sequentially rinsing pulled fused silica emitters for electrospray ionization (ESI) with acetone, water, an aqueous sodium hydroxide solution, water, and acetone again, followed by air drying. Next, the tip is dipped into a hydroxy-terminated polydimethylsiloxane solution and air dried. A final acetone rinse completes the process, which does not require disassembling the fluidic flow system or removing the nESI tip from its mount. This reconditioning not only prevents droplet formation but also restores the correct spray pattern, ensuring stable electrospray for 1–2 weeks. Tips can undergo multiple reconditionings. Although the protocol may lead to transient contaminant peaks, these diminish over 24 hours, and a list of potential contaminants is provided. [ABSTRACT FROM AUTHOR]

Purpose: To investigate post-market monitoring of the efficacy of antacids in different dosage forms available in Nigeria by evaluating the acid-neutralizing capacities (ANCs) of 28 antacid brands. Methods: The active pharmaceutical ingredients (APIs) were collected and the ANC was determined following the US Pharmacopeia monograph which involved reacting a minimum labeled dose (MLD) of the antacid with hydrochloric acid (HCl) and the excess was neutralized with sodium hydroxide (NaOH). All determinations were made using a pH meter at 37 ± 1 °C. Results: The ANC values of all brands ranged from 2.50 ± 0.23 to 28.10 ± 0.16 mEq/MLD. All the brands except one suspension contained simethicone alone and recorded ANC values above the acceptable limit (5 mEq/MLD). Antacids with aluminium hydroxide and magnesium hydroxide at amounts of ≥ 250 mg per 5 mL or tablet were associated with high ANC values. Antacids containing high amounts of single API such as sodium bicarbonate or calcium carbonate also had high ANC values. Conclusion: The ANC values of all the brands except one suspension (containing simethicone alone) are above the acceptable limit (5 mEq/MLD) and as such should be included on the drug labels. [ABSTRACT FROM AUTHOR]

Cracks in concrete structures are generally initiated due to the shrinkage i.e. the volume change characteristics of the concrete structures. In this experimental study, effects of the mix parameters related to alkaline liquid (AL) and recycled fine aggregate (RFA) on the shrinkage behaviour of environment-friendly mortar mixes produced with fly ash (FA)-based geopolymer binder and RFA were investigated and reported. To find out the effects of AL, concentration of liquid sodium hydroxide (LSH) was varied from 6M to 16M, ratio of liquid sodium silicate (LSS) to LSH in AL was varied from 1.0 to 2.5 and AL/FA ratio was considered as 0.4 and 0.6. Different fly ash-based geopolymer mortar mix were produced depending on above-said combinations of mix parameters along with the RFA content (by weight) of 10%, 20%, 30%, 40% and 50% in lieu of natural fine aggregate. Prismatic specimens (25 mm × 25 mm × 285 mm) were cast and cured at ambient air temperature to determine the shrinkage behaviour. Higher RFA content in mix, higher LSS/LSH ratio in AL and higher AL/FA ratio resulted in higher shrinkage value. But, lesser shrinkage value was noticed for those specimens of mortar mix with the consideration of higher concentration of LSH in AL with varying RFA content. [ABSTRACT FROM AUTHOR]

To reduce the risk of adsorption of granular activated carbon (AC) in the gastrointestinal tract, we successfully prepared a hollow-type spherical bacterial cellulose gel encapsulated with AC (ACEG) and evaluated its pH tolerance and adsorption capacity. The bacterial cellulose gel membrane of ACEG features a three-dimensional mesh structure of cellulose fibers, allowing the selective permeation of substances based on their size. In this study, the preparation method of ACEGs was investigated, and the indole saturation adsorption capacity of the obtained gel was measured. We modified the gel culture nucleus gel from calcium alginate gel to agar gel, facilitating the encapsulation of previously challenging particles. The new preparation method used sodium hydroxide solution for sterilization and dissolution to remove the debris of Komagataeibacter xylinus, which was feared to remain in the bacterial cellulose membrane. This treatment was also confirmed to have no effect on the adsorption capacity of the AC powder. Therefore, this new preparation method is expected not only to improve the performance of ACEGs but also to be applied to a wide range of adsorbent-encapsulated hollow-type bacterial cellulose gels. [ABSTRACT FROM AUTHOR]

In this research, the dietary fibers (DFs) from ginseng residue were extracted by employing three different extraction methods (alkaline: AL, acidic: AC, enzymatic: EN). The extracted DFs were characterized in terms of their structural and functional properties. The results clearly showed that, regardless of the extraction methods, all DF samples exhibited representative infrared spectral features. The DF extracted by AC (citric acid) had more porous structures with a looser configuration, in conjunction with high apparent viscosity, whereas the DF extracted by EN (α-amylase and protease) exhibited higher thermal stability. Moreover, the monosaccharide composition of the DF samples was significantly influenced by the extraction method type. The DF from ginseng residue extracted by AC had the highest functional properties, such as water holding capacity (8.16 g/g), oil holding capacity (3.99 g/g), water swelling capacity (8.13 g/g), cholesterol-absorption capacity (12.85 mg/g), bile acid absorption capacity (91.51 mg/g), nitrite ion absorption capacity (124.38 ug/g at pH 2.0), glucose absorption capacity (52.67 mg/g at 150 mmol/L), as compared to those of DF extracted by the EN and AL (sodium hydroxide) methods. Hence, ginseng residue-derived DF extracted by the AC method may be potentially employed in the preparation of functional food ingredients. [ABSTRACT FROM AUTHOR]

This paper presents an experimental approach to the study of the compressive strength, isothermal calorimetry and life cycle assessment (LCA) of alkali-activated pastes based on soda–lime–silica glass, established to investigate the effect of the nature and proportion of the activator. Four different activators are compared: Portland cement, sodium silicate, sodium carbonate (at four percentages by weight: 5, 10, 15 and 25 wt% relative to glass) and sodium hydroxide (3.5 wt%). Portland cement and sodium carbonate were added in dry form (powder), while sodium hydroxide (pellets) and silicate were used in solution. At room temperature, glass exhibited slow reaction kinetics, with mechanical performance increasing significantly beyond 28 days of curing. The nature of the activator had a direct impact on the mechanical performance of the activated glass. Cement-activated pastes and those containing 25 wt% of sodium carbonate developed strength at an early age (0–7 days). The other activators showed lower strength development before 28 days of reaction. While a higher activator content improved short-term performance, it also increased the environmental impact, primarily due to the activator. The LCA, conducted on 11 indicators, revealed that the environmental impact was largely driven by the type and amount of activator used. A performance impact indicator (PII) related to global warming was introduced to compare pastes with different performance values. At an early age (0–28 days), the PII was lower when the activator level was high but decreased over time as the strength improved. In terms of long-term performance (360 days), hydroxide and sodium carbonate (10 wt%) achieved compressive strengths of 91 and 74 MPa, respectively. These systems offered a balance between high performance and a reduced environmental impact, making them of interest for sustainable applications. [ABSTRACT FROM AUTHOR]

Recycled manure solids (RMS) are dried cow dung processed using a manure dewatering machine and subsequently sun-dried to ~ 20% moisture. Benefits of RMS include abundant availability, low cost, and eco-friendliness, but its use as bedding material for cows is hindered by a moisture content that promotes microbial growth. This in vitro study evaluated impacts of calcium hydroxide (CH; 5 and 7.5%) and sodium hydrosulphate (SHS; 6 and 8%), independently and in combinations, at various depths of RMS, on physicochemical and microbial properties. The CH-treated groups had increased pH and reduced moisture on Day 0. Incorporating 7.5% CH + 6% SHS at 15–20 cm, and 7.5% CH + 8% SHS at all depths, effectively suppressed Escherichia coli and Klebsiella spp. Furthermore, a combination of 7.5% CH + 8% SHS at 20 cm inhibited coliform growth, whereas 7.5% CH with 6% SHS inhibited Streptococcus spp. In conclusion, a combination of 7.5% CH with either 6 or 8% SHS at a depth of 15 cm in RMS was particularly effective in controlling environmental mastitis-causing pathogens, specifically E. coli and Klebsiella spp. [ABSTRACT FROM AUTHOR]

Some efforts have proposed the utilization of Sidoarjo mud for geopolymer paste. However, the original dry mud in geopolymer concrete showed decreased compressive strength and increased required water. In this paper, the one-part method is proposed to reduce the water in the mixture. First, the mud was chemically flocculated. Then, the dry mud was mixed with fly ash, activated geothermal silicate, and sodium hydroxide mixture in solid form before then the distilled water was added. This reduced the required water to 50% compared to the two-part method. The flocculant sedimented heavy metal that resulted in higher compressive strength at a later age. At 28 days, dry flocculated mud showed higher compressive strength than the original dry mud, with a compressive strength of 13 MPa and 11 MPa, respectively. This is because of the increase of silica, alumina, and iron content from 70% in dry LUSI to 75% in dry flocculated mud. [ABSTRACT FROM AUTHOR]

Submerged plants and related disturbances can affect both the phosphorus (P) release and the microbial communities in sediments. In this study, a sediment resuspension system was constructed, and P variability characteristics influenced by Vallisneria natans (V. natans) and the response mechanism of the microbial community were studied. The results indicated that the total phosphorus (TP) content increased from 678.875 to 1019.133 mg/kg and from 1126.017 to 1280.679 mg/kg in sediments and suspended solids (SSs) during the sediment resuspension process, respectively. Organic P (OP) increased by 127.344 mg/kg and 302.448 mg/kg in sediments and SSs after the disturbance, respectively. The microbial communities in the sediments and the leaves of V. natans had higher Chao values after the disturbance, while Shannon values decreased after the disturbance compared to the control in SSs. Proteobacteria had the highest abundance with the value of 51.1% after the disturbance in the sediments and SSs, and the abundance values of Proteobacteria in rhizomes and leaves of V. natans could reach 73.2% on average. Chloroflexi, Acidobacteria, and Firmicutes were also the main phyla in the sediment resuspension system. Sodium hydroxide extractable P (NaOH-P) in sediments could reduce the bioavailability of this P fraction under disturbance conditions. The decrease in the abundance of Bacteroidetes and Nitrospirae indicated that they were more sensitive to the disturbance, and the rotational speed changed the survival conditions for the Bacteroidetes and Nitrospirae. The response mechanism of microbial community during the sediment resuspension process could reflect the influence of the microbial community on the changing characteristics of P and could provide a theoretical foundation for P control at the micro level. [ABSTRACT FROM AUTHOR]

This study investigates the impact of strontium (Sr) additions on the corrosion resistance of an LM6 (A413) aluminium alloy. By incorporating varying concentrations of Sr (0.01 wt.% and 0.05 wt.%), the morphological and corrosion behaviours of the alloy were analysed under different corrosive environments, including sulphuric acid, sodium hydroxide, and sodium chloride solutions. The results demonstrate that Sr modifications significantly enhance the alloy's corrosion resistance, with the most substantial improvement observed at 0.05 wt.% Sr. The analysis revealed that the weight loss of the alloy in sulphuric acid decreased by 2.5% with 0.05 wt.% Sr after 10 days of immersion, due to the formation of a stable passive oxide layer. In sodium hydroxide, however, the weight loss was reduced by 5% with 0.05 wt.% Sr after 10 days, indicating aggressive uniform corrosion. In the 3.5% sodium chloride solution, the corrosion rates remain relatively low, and the 0.05 wt.% Sr alloy showed a decrease in corrosion product formation over time, suggesting enhanced resistance. Detailed surface analyses, including 3D profiling and morphology assessments, revealed that Sr additions refine the eutectic silicon phase, transforming it from a coarse to a more desirable fibrous or lamellar structure, thus improving the alloy's overall performance. The innovative findings underscore the potential of Sr as an effective microstructural modifier for enhancing the durability and longevity of Al-Si alloys in corrosive environments. [ABSTRACT FROM AUTHOR]

Alkali activated materials (AAMs) offer significant advantages over traditional materials like Portland cement, but require the use of strong alkaline solutions, which can have negative environmental impacts. This study investigates the synthesis of AAMs using metakaolin and wollastonite, aiming to reduce environmental impact by eliminating sodium silicate and using only sodium hydroxide as an activator. The hypothesis is that wollastonite can provide the necessary silicon for the reaction, with calcium from wollastonite potentially balancing the negative charges usually countered by sodium in the alkaline solution. This study compares raw and carbonated wollastonite (AAM-W and AAM-CW) systems, with raw materials carefully characterized and binding networks analyzed using TGA, FT-IR, and XRD. The results show that while wollastonite can reduce the amount of sodium hydroxide needed, this reduction cannot exceed 50%, as higher substitution levels lead to an insufficiently alkaline environment for the reactions. The carbonation of wollastonite enhances the availability of silicon and calcium, promoting the formation of both N-A-S-H and C-A-S-H gels. [ABSTRACT FROM AUTHOR]

Sodium hydroxide (NaOH) is increasingly drawing attention as a highly selective etchant for femtosecond laser-modified fused silica. Unprecedented etching contrasts between the irradiated and pristine areas have enabled the fabrication of hollow, high-aspect-ratio structures in the bulk of the material, overcoming the micrometer threshold as the minimum feature size. In this work, we systematically study the effect of NaOH solutions under different etching conditions (etchant concentration, temperature, and etching time) on the tracks created by tightly focused femtosecond laser pulses to assess the best practices for the fabrication of hollow nanostructures in bulk fused silica. [ABSTRACT FROM AUTHOR]

Chemical activation of geopolymer concrete is critical for improving its performance. The purpose of this research is to improve the chemical activation of self-compacted fly ash-based geopolymer concrete exposed to chlorides using magnetized water. A multicompound activator containing sodium hydroxide (SH) and sodium silicate (SS) was used to activate fly ash. Various SS/SH ratios (1.0–3.0), various molarities of SH (8–16 M), and MW of 1.2 tesla were considered. Slump flow, L-box, v-funnel, compressive strength, chloride profile, and X-ray diffraction approaches were performed. The results confirmed that the optimal concentration of SH increased from 14 M in nonmagnetized concrete to 16 M in magnetized concrete, indicating that MW has a positive impact on the chemical activation and consequently the geopolymerization reaction. Concrete workability decreased as the SH concentration and SS/SH ratio increased. Using an SS/SH ratio of 3.0 results in superior mechanical behavior and increased chloride penetration resistance. [ABSTRACT FROM AUTHOR]

This research investigates the manufacturing and characterisation of polyester-based composites reinforced with jute fibres and red mud particulates. The motivation stems from the need for sustainable, high-performance materials for applications in industries, like aerospace and automotive, where resistance to erosion is critical. Jute, a renewable fibre, combined with red mud, an industrial byproduct, offers an eco-friendly alternative to conventional composites. The composites were fabricated using compression moulding with varying red mud contents (10, 20, and 30 wt.%) and a fixed 40 wt.% of jute fibre. Fibre treatments included sodium hydroxide (NaOH) and silane treatments to improve bonding and performance. Erosion tests were performed using an air-jet erosion tester, examining the effects of the red mud content, fibre treatment, and impact angles. Scanning Electron Microscope (SEM) analysis provided insights into the erosion mechanisms. A distinctive reduction in erosion rates at higher impact angles (30°–60°) was observed, attributed to the semi-ductile nature of the composites. The addition of red mud enhanced erosion resistance, although an excess of 30 wt.% reduced resistance due to poor surface bonding. Silane-treated composites showed the lowest erosion rates. This study provides new insights into the interplay among material composition, fibre treatment, and erosion dynamics, contributing to the development of optimised, eco-friendly composite materials. [ABSTRACT FROM AUTHOR]

One material that can be used in bone and soft tissue engineering is bioglass. By adhering to bone tissues and forming an apatite layer that further starts the biomineralization process, it can also encourage skin regeneration and wound healing in addition to playing a significant part in the healing processes of bone fractures.In this research, Syrian clay was used as a cheap silica source for preparation bioglass by melting method. Pure silica was isolated by mixing clay with sodium hydroxide in the following amounts (1:1), (2:1), (3:1), treated at different temperatures (700, 800, 900)˚C, treated with HCl solution, filtrated, dried, the yield reached to 96% with purity of 99% when clay was mixed with NaOH by (2:1) and treated at 800˚C. Bioglass was prepared using isolated silica according to thermal program, the formation of bioglass was confirmed by XRD, IR and biodegradability test, which confirmed formation of hydroxyapatite, on the surface which confirmed the biological effectiveness of the prepared bioglass. [ABSTRACT FROM AUTHOR]

Foshou yam (Dioscorea opposita Thunb.), cultivated as a vegetable in the region of eastern Hubei Province, China, is a nutritious delicacy. Polysaccharides in the genus Dioscorea play important roles in health-promoting activities. Previous extraction methods used to obtain polysaccharides from Foshou yam (FYP) included water and enzymes, but not alkali conditions. The extraction methods greatly influenced the structure and biological properties of polysaccharides. Hence, in the present work, the alkali extraction of FYP was explored and optimised using the response surface method. The characterisation and antioxidant activity of FYP were also investigated. The results showed that the optimal extraction conditions were as follows: sodium hydroxide concentration, 1.0 mol/L; extraction time, 8 h; and solvent-to-material ratio, 10 mL/g. Under these conditions, the FYP extraction yield was 64.52 ± 0.23%. FYP contained 91.70% of the total sugar with a minimal amount of protein. FT-IR analysis revealed the presence of α-D-glucopyranose in FYP. Congo Red tests indicated that the triple helical conformation in FYP did not exist. In addition, in vitro antioxidant activity experiments revealed that FYP exhibited good scavenging capacity on DPPH and superoxide anion free radicals. These results indicated that the FYP can be used as a novel natural antioxidant in the functional food industries. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the effects of treatment with sodium hydroxide on the nutritional value of banana (Musa acuminata) trees to see if they can be used as a source of fibre for ruminants since there is large banana production and consequently some waste. The samples were collected and dried in an oven with a controlled air flow. They were then sprinkled with a sodium hydroxide solution (2, 4, 6 and 8% of dry matter) and placed in a suitable container. The chemical properties were analysed. The results show that sodium hydroxide treatment leads to a significant decrease in neutral fibre and acid lignin contents in both leaves and pseudostems. A significant (p < 0.05) increase was observed in ash, and digestibility values were lower in leaves, confirming the values for neutral detergent fibres. The total amount of gas produced was measured after 4, 8, 12, 24, 48, 72 and 96 h of incubation. The results showed that the gas production in the leaves was lower in all treatments compared to the pseudostem, which was consistent with the digestibility results. Analysis of the results showed that the best NaOH concentration to improve the nutritional value of M. acuminata was 6 and 8%. [ABSTRACT FROM AUTHOR]

In the present study, the evolution of free water content in five different alkali-activated slag (AAS) systems was continuously monitored and compared using 1H low-field NMR. The alkali activators used were waterglass solutions with three different moduli (1.2, 1.4, and 1.6), sodium hydroxide solution, and sodium sulfate solution. The findings reveal that the type of activator significantly affected the dynamic changes in the relative free water content. Notably, an increase in free water content was observed in the early stages of hydration of all AAS systems except for those activated by sodium sulfate solution. Additionally, this study investigated the relationship between changes in free water content and hydration heat in the AAS systems, dividing the initial 24 h of AAS hydration into three stages. The results demonstrate that free water can serve as an effective probe for monitoring the hydration process in fresh AAS pastes, offering valuable insights alongside traditional thermal signals. [ABSTRACT FROM AUTHOR]

This study shows the influence of the inclusion of abaca fiber (Musa Textilis) on the coefficients of consolidation, expansion, and compression for normally consolidated clayey silt organic soil specimens using reconstituted samples. For this purpose, abaca fiber was added according to the dry mass of the soil, in lengths (5, 10, and 15 mm) and concentrations (0.5, 1.0, and 1.5%) subjected to a curing process with sodium hydroxide (NaOH). The virgin and fiber-added soil samples were reconstituted as slurry, and one-dimensional consolidation tests were performed in accordance with ASTM D2435. The results showed a reduction in void ratio (compared to the soil without fiber) and an increase in the coefficient of consolidation (Cv) as a function of fiber concentration and length, with values corresponding to 1.5% and 15 mm increasing from 75.16 to 144.51 cm2/s. Although no significant values were obtained for the compression and expansion coefficients, it was assumed that the soil maintained its compressibility. The statistical analysis employed hierarchical linear models to assess the significance of the effects of incorporating fibers of varying lengths and percentages on the coefficients, comparing them with the control samples. Concurrently, mixed linear models were utilized to evaluate the influence of the methods for obtaining the Cv, revealing that Taylor's method yielded more conservative values, whereas the Casagrande method produced higher values. [ABSTRACT FROM AUTHOR]

In recent years, magnesium slag has been used as a raw material for solid waste treatment using the carbonization method and has proven to be promising in reducing carbon emissions. In this study, the alkali activation reaction was introduced to promote the carbonization of magnesium slag. The resulting mechanical properties, microstructural attributes, and carbonization mechanism were studied by varying the sodium hydroxide content, temperature, and carbon dioxide concentration during the reaction process. The results showed that the amounts of calcium hydroxide, C-S-H, and calcium carbonate in the reaction products increased with the sodium hydroxide content, which enhanced the compressive strength of the composite. However, it does not influence the carbonization mechanism with the increasing reaction temperature, which only elevates the reaction rate. With the increase in the carbon dioxide concentration during alkali activation, the carbonization reaction is dominated by the amount of CO2 dissolved in the reaction medium, and the carbonization mechanism is changed. Thus, a significant decrease in the calcium hydroxide content and a sharp increase in the calcium carbonate content in the products occurred, which significantly improved the compressive strength of the resulting magnesium slag composite. Among them, the maximum compressive strength is 6.83 MPa. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tailing storage facilities are very complex structures whose failure generally leads to catastrophic consequences in terms of casualties, serious environmental impacts on local biodiversity, and disruptions in the mineral supply. For this reason, structures at risk must be reinforced or decommissioned. One possible option is its reinforcement with compacted filtered tailings stabilized with binders. Alkali-activated binders provide a more sustainable solution than ordinary Portland cement but require an optimization of the tailing–binder mixture, which, in some cases, can lead to a substantial experimental effort. Statistical models have been used to reduce the number of those experiments, but a rational design methodology is still lacking. This methodology to define the right mixture for a required strength should consider both the mixture components and in situ conditions. In this paper, response surface methods were used to plan and interpret unconfined compression strength test results on an iron tailing stabilized with alkali-activated binders. It was concluded that the fly ash content was the most important parameter, followed by the liquid content and sodium hydroxide concentration. From the obtained results, several statistical models were defined and compared according to the definition of a strength prediction model based on a mixture index parameter. It was interesting to observe that models with the porosity cement index still provide reasonable adjustment even when different tailings' water contents are considered. [ABSTRACT FROM AUTHOR]

Achieving highly selective, highly responsive detection of formaldehyde gas at ppb level at room temperature is highly challenging for air monitoring and life health observation. Therefore, in this paper, low-cost, easy-to-fabricate, highly responsive as well as highly selective Zn 2 SnO 4 /SnO 2 (ZTO/SnO 2) metal-oxide semiconductor gas sensors have been successfully prepared by using one-pot hydrothermal method. The results showed that the synergistic effect of the n-n heterojunction formed between ZTO/SnO 2 prepared by this method led to a substantial increase in the sensitivity to the target gases, and ZTO/SnO 2 -3 a higher response (291) to 100 ppm formaldehyde compared to the response values of pure samples of Zn 2 SnO 4 (20.4) and pure SnO 2 (6.99) at room temperature. In addition, the response value for formaldehyde reached about 16.5–295 times higher than that for other common hazardous gases (100 ppm) in our lives. The ZTO/SnO 2 -3 sample with 1 mol/L NaOH was homogeneous and small, exposing as much surface as possible, and the theoretical minimum detection limit was calculated to be 50 ppb. Therefore, the large specific surface area and active adsorption/interaction sites are favorable for gas sensing. This work provides an excellent way to prepare gas-sensitive characteristic sensors using NaOH to improve the surface structure. [ABSTRACT FROM AUTHOR]

A large amount of pyrite concentrate slag washing solution is produced in China every year, and this contains valuable components such as Cu2+ and Au. The traditional treatment method not only pollutes the environment but also wastes metal resources. For the washing solution containing Cu2+ 437 mg/L and Au 0.13 mg/L, two new processes comprehensive recovery schemes were developed and compared in this paper, namely iron powder replacement pore filtration and neutralization precipitation pore filtration. When the iron powder replacement pore filtration process was adopted, Cu2+ and Au were mainly comprehensively recovered in the form of a mixture of sponge copper and particulate gold. The test results showed that the replacement optimal conditions involved a pH of 3.0, iron powder dosage of 6 g/L, and replacement time of 3.0 h. After replacement, the filter cloth with below 1 μm pore size was used for filtration. The recovery rate of Cu2+ in the washing solution was 98.13 and the total recovery rate of Au was 95.83%. Otherwise, when the neutralization precipitation pore filtration process was adopted, Cu2+ and Au were mainly comprehensively recovered in the form of a mixture of copper hydroxide and particulate gold. The test results showed that sodium hydroxide was used as the precipitant and the optimum neutralization pH value was 6.5. After precipitation, the filter cloth with a below 1 μm pore size was used for filtration. The recovery rate of Cu2+ in the washing solution was 97.35% and the total recovery rate of Au was 93.54%. The economic benefit estimation of the two processes showed that the neutralization precipitation pore filtration process had the advantages of low material consumption, low cost and high economic benefit. [ABSTRACT FROM AUTHOR]

To solve the contradiction between reducing water-insoluble content and maintaining high viscosity in the preparation of modified guar gum for oilfield fracturing fluid, in this work, sodium 3-chloro-2-hydroxypropylsulfonate was used as a modifier to prepare sulfonated guar gum. Orthogonal and single-factor extrapolation experiments were conducted to explore the effects of reaction conditions and the optimal process was determined as follows: reaction temperature of 26 oC, reaction time of 2.0 h, sodium hydroxide as a mass fraction of guar gum of 1.0%, and sodium 3-chloro-2-hydroxypropyl sulfonate dosage as a mass fraction of guar gum of 0.5%. Furtherly, the temperature stability, filtration property, and inhibition of formation clay of the sulfonated products were investigated. The results showed that the apparent viscosity of 0.6% solution of guar gum was increased by 33%, the water-insoluble content was decreased by 0.42%, and the temperature stability, filtration resistance, and clay inhibition were all improved. Especially, the viscosity of cross-linked sulfonated guar gum is 100% higher than that of unmodified guar gum. The structure of sulfonated guar gum was characterized and confirmed by infrared spectrum, DSC, thermogravimetric, and elemental analysis. [ABSTRACT FROM AUTHOR]

This study focused on developing an effective cell wall-breaking method for Phaffia rhodozyma, followed by utilizing subcritical fluid extraction to isolate, extract, and concentrate astaxanthin from the complex fermentation products of P. rhodozyma. A comprehensive comparison of seven distinct methods for disrupting cell walls, including dimethyl sulfoxide treatment, lactic acid treatment, sodium hydroxide treatment, β-glucanase enzymatic digestion, β-mannanase enzymatic digestion, and a combined enzymatic treatment involving both β-mannanase and β-glucanase was conducted. The results identified the lactic acid method as the most effective in disrupting the cell walls of P. rhodozyma. The software, Design Expert, was used in the process of extracting astaxanthin from cell lysates using a subcritical extraction method. Through fitting analysis and response surface optimization analysis by Design Expert, the optimal extraction conditions were determined as follows: an extraction temperature of 41 °C, extraction frequency of two times, and extraction time of 46 min. These parameters facilitated the efficient extraction, concentration, and enrichment of astaxanthin from P. rhodozyma, resulting in an astaxanthin concentration of 540.00 mg/L. This result can establish the foundation for its high-value applications. [ABSTRACT FROM AUTHOR]