Influence of alkaline activators on mechanical properties of environmentally friendly geopolymer concrete under different curing regimes.

Previous studies highlighted the significance of tailoring alkaline activators (AA) to specific fly ash (FA) sources for optimal properties of geopolymer concrete (GPC). This study examines the influence of various AA's properties on mechanical properties and microstructures of local low-calcium FA-based GPC under varying curing conditions. A comprehensive investigation consists of several factors such as NaOH molarities (10 M, 12 M, 14 M, 16 M), Na 2 SiO 3 / N a O H ratios (1.5, 2.0, 2.5) and A A / F A ratios (0.5, 0.6). The results reveal a complex relationship, demonstrating that NaOH molarity positively influences compressive strength up to a threshold of 14 M, beyond which an adverse effect was observed while, the flexural strength was increased up to 16 M. Moreover, the study highlights the complex relationship between Na 2 SiO 3 / N a O H ratios and mechanical strengths. Notably, these properties exhibited an increase as the ratio rose up to 2.0, but a subsequent decrease was observed when the ratio reached 2.5. Moreover, proposed regression equations predict the compressive and flexural strengths of both ambient-cured GPC and heat-cured GPC with marginal statistical errors. The optimal GPC mix exhibited 49% lower embodied CO 2 emissions than the corresponding OPC concrete. GPC has higher cost, but it exhibited lower cost-to-strength ratio compared to OPC concrete.

Spectrophotometric determination of o-phenylphenol in canned drinks using three-phase hollow-fiber liquid phase microextraction.

A three-phase hollow-fiber liquid phase microextraction for o-phenylphenol (OPP) determination was developed. 1-octanol was employed as the organic phase, impregnated within the pores of the hollow fiber wall which was immersed in the sample solution, serving as a donor phase. OPP in the sample solution was extracted via octanol in the fiber pores into NaOH, which acted as the acceptor phase in the lumen of the fiber. The extracted OPP was then subjected to spectrophotometric detection at 712 nm using the indophenol blue reaction. The developed method showed a linear calibration curve (0.002-0.040 mg L-1) with high sensitivity (5.75 L mg-1), low limit of detection (0.31 µg L-1), and high recovery (73.6-94.8 %). Intra-day and inter-day precision at 2.1 µg L-1 OPP were 7.4 % (n = 12) and 10.9 % (n = 4) relative standard deviations, respectively. The determined OPP in various canned drinks was found to be between 2.0 and 17.8 µg L-1 using the developed method.

Chemical characterization of hibiscus rosa-sinensis plant fibers facilitated through design of experiments and artificial neural network hybrid approach.

The integration of natural fibers into Fiber Reinforced Polymers (FRPs) has emerged as a promising avenue for sustainable and high-performance composite materials. Natural fibers, derived from plants, offer notable advantages such as renewability, low cost, and environmental friendliness. Among these natural fibers, Hibiscus Rosa-Sinensis (HRS) plant fibers have gained significant attention owing to their widespread availability and unique mechanical properties. In this study, HRS fibers were chemically treated using Sodium Hydroxide (NaOH), Potassium Permanganate (KMnO4), and Acetic Acid (CH3COOH) at different weight percentages (3, 4, 5 Wt.%) and solutionizing times (1, 2, 3 h) based on Taguchi's L27 orthogonal array. The fibers, extracted from epidermis of the stems, underwent cleaning and chemical treatment after water retting. The crystallinity index, determined via X-ray Diffraction (XRD), indicated a maximum value of 65.77%. Thermo-gravimetric analysis (TGA) exhibited a degradation temperature of 365.24 °C and a material loss of 63.11%. Potassium Permanganate treatment at 4 Wt.% and 3 h of solutionizing time has yielded the best results. Multi-Layer Perceptron Artificial Neural Network (MLP-ANN) has been successfully applied to accurately predict the output physical characteristics of chemically treated HRS fibers using experimental data. The results are in close alignment with the literature. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses have provided valuable insights into the microstructure and constituents of the chemically treated HRS fibers. This research emphasises on the effectiveness of the chemical treatment process in enhancing the properties of HRS plant fibers for potential composite applications.

Cellulose nano-dispersions enhanced by ultrasound assisted chemical modification drive osteoblast proliferation and differentiation in PVA/HA bone tissue engineering scaffolds.

To develop a biological bone tissue scaffold with uniform pore size and good cell adhesion was both challenging and imperative. We prepared modified cellulose nanocrystals (CNCs) dispersants (K-PCNCs) by ultrasound-assisted alkylation modification. Subsequently, nano-hydroxyapatite (HC-K) was synthesized using K-PCNCs as a dispersant and composited with polyvinyl alcohol (PVA) to prepare the scaffold using the ice template method. The results showed that the water contact angle and degree of substitution (135°, 1.53) of the K-PCNCs were highest when the ultrasound power was 450 W and the time was 2 h. The dispersion of K-PCNCs prepared under this condition was optimal. SEM showed that the pore distribution of the composite scaffolds was more homogeneous than the PVA scaffold. The porosity, equilibrium swelling rate, and mechanical properties of the composite scaffolds increased and then decreased with the increase of HC-K content, and reached the maximum values (56.1 %, 807.7 %, and 0.085 ± 0.004 MPa) at 9 % (w/w) of HC-K content. Cell experiments confirmed scaffold has good cytocompatibility and mineralization capacity. The ALP activity reached 1.71 ± 0.25 (ALP activity/mg protein). In conclusion, the scaffolds we developed have good biocompatibility and mechanical properties and have great potential in promoting bone defect repair.

Activated Carbon for CO2 Adsorption from Avocado Seeds Activated with NaOH: The Significance of the Production Method.

The rise in atmospheric greenhouse gases like CO2 is a primary driver of global warming. Human actions are the primary factor behind the surge in CO2 levels, contributing to two-thirds of the greenhouse effect over the past decade. This study focuses on the chemical activation of avocado seeds with sodium hydroxide (NaOH). The influence of various preparation methods was studied under the same parameters: carbon precursor to NaOH mass ratio, carbonization temperature, and nitrogen flow. For two samples, preliminary thermal treatment was applied (500 °C). NaOH was used in the form of a saturated solution as well as dry NaOH. The same temperature of 850 °C of carbonization combined with chemical activation was applied for all samples. The applied modifications resulted in the following textural parameters: specific surface area from 696 to 1217 m2/g, total pore volume from 0.440 to 0.761 cm3/g, micropore volume from 0.159 to 0.418 cm3/g. The textural parameters were estimated based on nitrogen sorption at -196 °C. The XRD measurements and SEM pictures were also performed. CO2 adsorption was performed at temperatures of 0, 10, 20, and 30 °C and pressure up to 1 bar. In order to calculate the CO2 selectivity over N2 nitrogen adsorption at 20 °C was investigated. The highest CO2 adsorption (4.90 mmol/g) at 1 bar and 0 °C was achieved.

Comparative analysis of Escherichia coli Nissle 1917 ghosts quality: a study of two chemical methods.

The gram-negative bacterium Escherichia coli Nissle 1917 (EcN) has long been recognized for its therapeutic potential in treating various intestinal diseases. Bacterial ghosts (BGs) are empty shells of non-living bacterial cells that demonstrate enormous potential for medicinal applications. Genetic and chemical techniques can create these BGs. In the current study, we produced Escherichia coli Nissle 1917 ghosts (EcNGs) for the first time using benzoic acid (BA) and sodium hydroxide (SH). BA is a feeble acidic chemical that enhances gram-negative bacteria's external membrane permeability, reduces energy production, and decreases internal pH. SH has shown success in producing BGs from some gram-negative and gram-positive organisms. This research aims to produce EcNGs using the minimum inhibitory concentration (MIC) of SH and BA, specifically 3.125 mg/mL. We assessed the bacterial quality of the BGs produced using quantitative PCR (qPCR) and Bradford protein assays. Field emission scanning electron microscopy (FE-SEM) showed the three-dimensional structure of EcNGs. The study confirmed the presence of tunnel-like pores on the outer surface, indicating the preservation of cell membrane integrity. Importantly, this investigation introduces BA as a novel chemical inducer of EcNGs, suggesting its potential alongside SH for efficient EcNG formation.

Cellobionate production from sodium hydroxide pretreated wheat straw by engineered Neurospora crassa HL10.

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.

Effect of Solution-to-Binder Ratio and Molarity on Volume Changes in Slag Binder Activated by Sodium Hydroxide at Early Age.

This research investigates the impact of solution concentration and solution-to-binder ratio (S/B) on the volume changes in alkali-activated slags with sodium hydroxide at 20 °C. Autogenous and thermal strains are monitored with a customized testing device in which thermal variations are controlled. Consequently, both the autogenous strain and coefficient of thermal expansion (CTE) are determined. Heat flow and internal relative humidity (IRH) are also monitored in parallel, making this research a multifaceted study. The magnitudes of autogenous strain and CTE are higher than those of ordinary Portland cement paste. Decreasing the solution concentration or S/B generally decreases the autogenous strain (swelling and shrinkage) and the CTE. The shrinkage amounted to 87 to 1981 µm/m, while the swelling reached between 27 and 295 µm/m and was only present in half of the compositions. The amplitude of the CTE, which increases up to 55 µm/m/°C for some compositions while the CTE of OPC remains between 20 and 25 µm/m/°C, can be explained by the high CTE of the solution in comparison with water. The IRH of paste cannot explain the autogenous strain's development alone. Increasing S/B eliminates the self-desiccation-related decrease.

High temperature corrosion and oxide scale formation of nickel in molten NaOH at various basicity levels.

The corrosion behavior of alloy Ni 201 in molten sodium hydroxide (NaOH) at 600 °C was investigated at varying basicity levels of the molten NaOH. The ability for Ni 201 to form passivating oxides was investigated after immersion tests varying from 70 to 340 h under atmospheres of argon and argon with different partial pressure of water. Morphology and thicknesses of the corrosion products were characterized by Scanning Electron Microscopy (SEM) and crystallography of the corrosion products by X-ray Diffraction (XRD). Dynamic polarizations were made to investigate the effects of basicity and electrochemical potential. The results showed that Ni 201 corroded at a reduced rate in molten acidic NaOH compared to neutral NaOH due to the formation of NiO. The oxide scales formed on Ni 201 in acidic NaOH were shown to grow non-parabolically and did not result in full corrosion protection as the oxide scales showed crack development over time.

A dilute sodium hydroxide technique for radiolarian extraction from cherts.

Radiolarians have been used to determine geological ages and have contributed markedly to our understanding of Earth's history. Hydrofluoric acid (HF) has traditionally been used to extract radiolarian fossils from siliceous deposits (i.e., radiolarian cherts), but this acid is strictly regulated because of environmental and human health concerns. Here we report on the successful extraction of radiolarians from cherts using a low-concentration NaOH solution (1 mol/L NaOH) as an alternative to HF. The degree of chert dissolution in NaOH is strongly temperature-dependent and is limited at < 80 °C. However, even a 1 mol/L NaOH solution is sufficient to dissolve chert at 100 °C. Our new NaOH method yields better-preserved radiolarian fossils compared with the conventional HF method. The 1 mol/L NaOH solution is less hazardous, easier to handle, and has fewer effects on the environment and human health than HF. Therefore, this method can be widely used for research and teaching purposes in studies of radiolarian fossils, even in institutions where HF cannot be used owing to chemical restrictions.

Facile fabrication of next-generation sustainable brick and mortar through geopolymerization of construction debris.

Waste from construction and demolition (also known as CDW) is one of the most harmful environmental issues. This study's primary goal is to produce new mortar and brick materials from recycled concrete powder (RCP) and recycled brick powder (RBP), two of the most popular CDW. Geopolymeric mortar and brick samples were produced by passing RCP and RBP through sieve No. 50 (with sand filler if necessary) and combining them with an alkaline solution made of water glass (WG) and NaOH. In this study, the mixture was then cured for three days at 80 °C in an oven. The effects of filler, RBP amount, WG amount, and the concentration of NaOH alkaline solution on the samples' strength were examined. Additionally, XRF and SEM/XRD tests were performed to verify the materials' composition and microstructure. The mechanical strength of the samples showed an increase with the increase of RCP values, so the brick sample with filler showed the highest compressive strength, measuring 59.53 MPa. The study's samples exhibited strong mechanical properties. Additionally, all of the bricks' water absorption fell within the standard range. In summary, according to different standards, both waste concrete and waste brick can be used to produce geopolymer materials especially bricks for construction and paving purposes.

Inhibitory effects of glutathione peroxidase on microbial spoilage of crayfish (Procambarus clarkii) during refrigerated storage.

The variety of enzyme-based biological preservatives is limited. This study evaluated the effects of glutathione peroxidase (GSH-Px) on the quality of crayfish during refrigerated storage by measuring the pH, total volatile basic nitrogen, trimethylamine, and microbial contamination in crayfish muscle simulation system. The results revealed that 0.3% GSH-Px (CK3) not only suppressed the degradation of nitrogenous substances but also decreased the contamination levels of total viable, Enterobacteriaceae, and Pseudomonas counts (P < 0.05). Furthermore, the populations of Lactococcus, Aeromonas, and Massilia differed in the CK3 group compared to the other groups (P < 0.05) at the end of the storage (day 15). Moreover, the principal coordinate analysis showed that the colony composition of CK3 stored for 15 days was similar to that of the control group stored for 10 days. Therefore, GSH-Px exhibits antibacterial activity against Gram-negative bacteria and has good application potential in freshwater aquatic product preservation.

Chitin nanofibrils assisted 3D printing all-chitin hydrogels for wound dressing.

The direct ink writing technique used in 3D printing technology is generally applied to designing biomedical hydrogels. Herein, we proposed a strategy for preparing all-chitin-based inks for wound dressing via direct ink writing technique. The ß-chitin nanofibers (MACNF) with a high aspect ratio were applied as a nanofiller to modulate the rheological properties of the alkaline dissolved chitin solution. The printing fidelity significantly depends on the MACNF introduction amount to the composite ink. 5-10 wt% MACNF ratio showed superior printing performance. The printed scaffold showed a uniform micron-sized pore structure and a woven network of nanofibers. Due to the good biocompatibility of chitin and the stereoscopic spatial skeleton, this scaffold showed excellent performance as a wound dressing, which can promote cell proliferation, collagen deposition and the angiogenesis of wounds, demonstrating its potential in biomedical applications. This approach successfully balanced the chitinous printability and biofunctions.

Preparation of Activated Biocarbons from Cones and their Potential Application for Adsorption of Antibiotics (Tetracycline).

The pine cones (PC), spruce cones (SC) and fir cones (FC) were used for biocarbons preparation. Chemical activation with sodium hydroxide was applied to prepare activated biocarbons. All the materials under investigation were characterized by the N2 adsorption, scanning electron microscopy (SEM), elemental analysis (CHNS), infrared spectroscopy (ATR FT-IR), and the Boehm's titration method. Moreover, pHpzc (the point of zero charge) was determined. It was shown that cones are a good, cheap precursor from which biocarbons with a developed porous structure, characterized by good adsorption properties, can be obtained. All the obtained adsorbents are characterized mainly by a microporous structure. Moreover, they contain both acidic and basic surface functional groups (acidic ones prevail over basic ones). The tested activated biocarbons have large specific surface area values ranging from 578 to 1182 m2 g-1. The efficacy of selected materials in the adsorption of an essential contaminant of increasing concern, tetracycline (TC), was investigated. The experimental data were described using the Langmuir and Freundlich adsorption isotherm models. The maximum adsorption capacity of the tested biocarbons ranges from 200 to 392 mg g-1. Thermodynamic studies proved that adsorption is a spontaneous and endothermic process. In summary, economical and environmentally friendly adsorbents were obtained.

Synthesis and characterization of thermosensitive 2-hydroxypropyl-trimethylammonium chitin and its antibacterial sponge for noncompressible hemostasis and tissue regeneration.

Noncompressible hemorrhage is a leading cause of preventable death in battlefield/civilian trauma. The development of novel injectable and biodegradable hemostatic sponges, with rapid shape recovery and excellent antibacterial activity that can control hemorrhage in noncompressible bleeding sites and promote in situ tissue regeneration is still urgently needed. In this study, thermo/pH sensitive 2-hydroxypropyl-trimethylammonium chitins (QCHs) with low degree of quaternization substitution (DS: 0.07-0.23) and high degree of acetylation (DA: 0.91-0.94) were synthesized homogeneously for the first time. Their chemical compositions including DS and DA were characterized accurately by proton NMR for the first time. High strength QCH based sponges with good water/blood absorbency, rapid shape recovery and good antibacterial activity were prepared without using any crosslinkers but only due to their thermosensitive property, since they are soluble at low temperature but insoluble at high temperature. Compared with commercial products, the QCH sponges with cationic groups had the stronger pro-coagulant ability, better hemostatic effect in normal/heparinized liver perforation and femoral artery models in rats and porcine subclavian arteriovenous resection model. Moreover, the porous structure and biodegradability of the QCH sponges could promote in situ tissue regeneration. Overall, the QCH sponges show great clinical translational potential for noncompressible hemorrhage and tissue regeneration.

Time-resolved transcriptomic and proteomic profiling of Heyndrickxia coagulans during NaOH-buffered L-lactic acid production.

The L-lactic acid (L-LA) fermentation process, based on sodium hydroxide neutralization, demonstrates environmental friendliness during product extraction. However, lactate fermentation is hindered by the pronounced stress effect of sodium lactate on the strain compared with calcium lactate. In this study, we performed time-resolved transcriptomic and proteomic analyses of Heyndrickxia coagulans DSM1 during NaOH-buffered L-LA production. The expression levels of the glycolytic genes demonstrated an initial increase followed by a subsequent decrease, whereas the tricarboxylic acid cycle genes exhibited an initial decrease followed by a subsequent increase throughout the fermentation process. Moreover, we identified clusters of genes consisting of transcription factors and ATP-binding cassette (ABC) transporters that demonstrate a progressive elevation of expression levels throughout the fermentation process, with significant upregulation observed at later stages. This investigation yields valuable insights into the response mechanisms of H. coagulans during NaOH-buffered L-LA fermentation and presents potential targets for metabolic engineering.

Optimization of Alkali Treatment for Production of Fermentable Sugars and Phenolic Compounds from Potato Peel Waste Using Topographical Characterization and FTIR Spectroscopy.

Potato peel waste (PPW) was utilized as a bio-template for the production of valuable compounds such as reducing sugars (RS), total sugar (TS) and total phenolic compounds (TPC). Two methods of alkali treatments, i.e., chemical (NaOH) and thermochemical (NaOH assisted with autoclaving) processes, were employed for the deconstruction of PPW. Response surface methodology (RSM) was used to study the effects of alkali concentration (0.6-1.0 w/v), substrate concentration (5-15 g) and time (4-8 h) on the extraction of RS, TS and TP from PPW. The application of alkali plus steam treatment in Box-Behnken design (BBD) with three levels yielded the optimum releases of RS, TS and TP as 7.163, 28.971 and 4.064 mg/mL, respectively, corresponding to 10% substrate loading, in 0.6% NaOH for 8 h. However, the alkali treatment reported optimum extractions of RS, TS and TP as 4.061, 17.432 and 2.993 mg/mL, respectively. The thermochemical pretreatment was proven a beneficial process as it led to higher productions of TP. FTIR and SEM were used to analyze the deterioration levels of the substrate. The present work was used to explore the sustainable management of PPW, which is a highly neglected substrate bioresource but is excessively dumped in open environment, raising environmental concerns. The cost-effective methods for the breakdown of PPW starch into fermentable sugars might be utilized to extract valuable compounds.

Assessment of the application for renewal of the authorisation of a feed additive consisting of sodium hydroxide for dogs, cats and ornamental fish (Brenntag Holding GmbH and Electroquímica de Hernani, S.A.).

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the assessment of the application for renewal of authorisation of sodium hydroxide as a technological additive (acidity regulator) for dogs, cats and ornamental fish. The applicants have provided evidence that the additive currently on the market complies with the existing conditions of authorisation. There is no evidence that would lead the FEEDAP Panel to reconsider its previous conclusions. Thus, the Panel concluded that the additive remains safe for all animal species and the environment under the authorised conditions of use. Regarding user safety, the additive is corrosive and therefore the provision of the authorisation that 'breathing protection, eye protection, gloves and protective clothing shall be used during handling' should be confirmed. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Inhibition of human cervical cancer development through p53-dependent pathways induced by the specified triple helical ß-glucan.

This study demonstrates that the purified ß-glucan (LNT) with a triple helix and relatively narrow molecular weight distribution, extracted and purified from artificially cultured Lentinus edodes, showed a significant cervical cancer inhibition with little cytotoxicity against normal cells in vitro and in vivo. From the in vitro data, the potential mechanism of anti-cervical cancer was preliminarily revealed as follows: LNT was firstly recognized by the human cervical cancer cell line of Hela and induced cell proliferation inhibition through p21 and apoptosis via a mitochondrion-dependent pathway by targeting the tumor suppressor of p53, indicated by an increase in reactive oxygen species (ROS) generation and a loss of mitochondrial membrane potential (Δψm), in a significant dosage-dependent manner. Meanwhile, LNT repressed tumor growth with an inhibition ratio of 61.2 % and induced tumor cell apoptosis through endogenous MDM2/p53/Bax/mitochondrion signal pathway by up-regulating the expression of p53, Bax, Cyt. c, caspase 9, and caspase 3, as well as down-regulating Bcl-2, MDM2, and PARP1 levels in Hela cells-transplanted BALB/c nude mice. This study provides a scientific basis for the clinical treatment of cervical cancer with LNT as a potential drug candidate characterized by the triple helix and specified molecular weight with a relatively narrow distribution.

Water soluble AIEgen-based thermosensitive and antibacterial hydroxypropyl chitin hydrogels for non-invasive visualization and wound healing.

Antimicrobial hydrogels containing antibacterial agents have been extensively studied for postoperative infections, wound repair and tissue engineering. However, the abuse of antibiotics has led to the enhancement of bacterial resistance and traditional antibacterial agents are losing their effect. Therefore, fabricating novel and efficient antibacterial hydrogels with enhanced photodynamic antimicrobial activity, good biocompatibility, biodegradability and injectability are highly desirable for clinical application. Herein, a fluorescent and sunlight-triggered synergetic antibacterial thermosensitive hydrogel (red fluorescent hydroxypropyl chitin, redFHPCH) is constructed based on a new water-soluble AIEgen (aggregation-induced emission fluorogen) covalently introduced in hydroxypropyl chitin for non-invasive visualization and wound healing. The thermosensitive redFHPCH solution showing good injectability with fluidity at low temperature was completely transformed into hydrogel under body temperature. The in vitro and in vivo visualization and reactive oxygen species (ROS) generation of the redFHPCH hydrogel are demonstrated clearly because of its excellent AIE fluorescence imaging quality in the red/near-infrared region and superefficient ROS production by sunlight. Moreover, the redFHPCH hydrogel with positively charged quaternary ammonium groups displays a strong synergistic antibacterial effect for healing of infected wound under sunlight irradiation. We believe that this novel strategy can open a new door to explore diversified and multifunctional hydrogels for clinical application.