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Corundum and transition alumina powders are commonly produced through the Bayer process—that is, by digestion of bauxite in a sodium hydroxide solution, followed by gibbsite precipitation, which contains significant amounts of Na+ ions. During the de‐hydroxylation of gibbsite, Na+ is associated with retardation of the structural phase transformations between transition alumina and corundum (α‐Al2O3) phases, although the exact role of Na is unclear. The influence of Na+ ions on the phase transformation of γ‐Al2O3 to α‐alumina was investigated by varying the concentration of NaOH in aqueous γ‐Al2O3 suspensions. The phase transformation behavior of γ‐Al2O3 was monitored through thermal analysis, X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectrometer (XPS), and transmission electron microscope. As the Na concentration in γ‐alumina suspensions increased, the amount of α‐Al2O3 decreased in samples that were heat treated at 1200°C for 2 h. XPS analysis indicated that washing transition alumina powders with NH4OH solutions had decreased the surface concentration of Na+ and facilitated the phase transformation to α‐Al2O3. [ABSTRACT FROM AUTHOR]

It is imperative to minimize radioiodine release to the environment through gaseous emissions of spent fuel reprocessing facilities, thereby mitigating its potential impact on the general public. One effective and widely adopted strategy for achieving this objective is caustic scrubbing, a method that involves the absorption of molecular iodine from gaseous streams using caustic soda ( NaOH ) solution in a packed column. In-depth laboratory-scale experiments were conducted to ascertain the overall volumetric mass transfer coefficient K G a for the absorption of dilute iodine vapor from air into a caustic soda solution in a packed column and to establish optimum performance parameters for this process. The investigation yielded noteworthy findings: K G a increased proportionately to (Gas phase Reynolds number)1.0 at constant liquid flow rates across all types of packing tested. K G a displayed relative independence from liquid velocities for high and moderate NaOH concentrations. However, this coefficient varied proportionately to (Liquid phase velocity)0.26 to 0.42 at lower NaOH concentrations under conditions of high gas flow rates NaOH . As the height of the column increased, K G a was found to decrease slightly. The presence of NOx at an inlet concentration of 9000 ppm in the gaseous stream led to a reduction in the mass transfer coefficient of iodine, particularly at low NaOH concentrations. In summary, the study underscores the importance of caustic scrubbing as an effective means to minimize the release of radioiodine. The investigation's results provide valuable insights into optimizing performance parameters for this process, contributing to enhanced environmental protection. [ABSTRACT FROM AUTHOR]

Heating buildings with solar energy is challenged by the seasonal mismatch between solar availability and heating demand. Thermochemical energy storage is a promising technology to overcome this challenge because of its high energy density. In building applications, space requirement is also an important consideration. Therefore, both the storage space and collector areas are important considerations, with only the latter often being neglected in previous studies. This paper proposes a novel two-stage thermochemical heat pump heating system based on the working pair of NaOH/H2O. We demonstrate that this system can work with a concentration difference (70% wt–30% wt) for the climate in hot summer and cold winter regions in China. The energy storage density based on the discharged solution is 363 kWh/m3. With this solar-driven thermochemical heat pump heating system, 35.13 m2 of collectors and 10.48 tons of 70% wt NaOH solution are sufficient to complete a full charge–discharge cycle and meet the heating demand of a single-family house (winter space heating + DHW: 9370 kWh, summer DHW: 2280 kWh). The theoretical maximum storage for solution (discharged + water tank) is 32.47 m3. Compared with the sensible seasonal storage alternative, the collector area is reduced by 12.5% and the storage space is reduced by 59%, with a possible further reduction through optimization. With the potential to be further optimized for space saving, the two-stage solar–NaOH heat pump heating system is an energy-efficient and space-efficient heating system for buildings in the hot summer and cold winter regions of China. [ABSTRACT FROM AUTHOR]

Although several therapeutic effects have been attributed to wild blackthorn fruits, their use is still negligible. Purification of the antioxidant-active fraction, obtained from wild blackthorn fruits by hot ammonium oxalate extraction (Ao), yielded seven fractions after successive elution with water, sodium chloride and sodium hydroxide solutions. The purified fractions differ in carbohydrates, proteins, and phenolics. About 60% of the applied Ao material was recovered from the column, with the highest yields eluted with 0.25 M NaCl solution, accounting for up to 70 wt% of all eluted material. Analyses have shown that two dominant fractions (3Fa and 3Fb) contain 72.8–81.1 wt% of galacturonic acids, indicating the prevalence of homogalacturonans (HG) with a low acetyl content and a high degree of esterification. The low content of rhamnose, arabinose and galactose residues in both fractions indicates the presence of RG-I associated with arabinogalactan. In terms of yield, the alkali-eluted fraction was also significant, as a dark brown-coloured material with a yield of ~15 wt% with the highest content of phenolic compounds of all fractions. However, it differs from other fractions in its powdery nature, which indicates a high content of salts that could not be removed by dialysis. [ABSTRACT FROM AUTHOR]

Industrial production operations generate huge amounts of heavy metals enriched sludge. Due to inadequate management and illegal disposal practices, this waste sludge can deteriorate human and environmental health. For sustainable environmental development and conserving human health, sludge should be recycled to recover the heavy metals and the treated sludge (with permissible or safe limits of heavy metals) should be used to improve the soil fertility and physical properties. Herein, a study is carried out to identify the optimum concentration of sulphuric acid (H2SO4) to remove copper (Cu), nickel (Ni) and chromium (Cr) from the waste sludge and the number of organic matter residues that remained after the acid digestion. Besides, the optimum pH to precipitate Cu, Ni, and dissolute the Cr in the form of metal hydroxide is determined. Acid digestion is done by using H2SO4 and precipitation is done by sodium hydroxide (NaOH). The heavy metals concentrations were determined through inductively coupled plasma-optical emission spectroscopy (ICP-OES). The result showed that the concentration of H2SO4 is significantly affecting the sludge organic content. The respective percentage of Cu, Ni and Cr removed by 30% of H2SO4 were 98.99, 99.27 and 97.22%. At pH 14, Cu, Ni and Cr precipitation to form metal hydroxide was the highest. About 4.01%, 23.75% and 13.93% of copper hydroxide, nickel hydroxide and chromium hydroxide are, respectively, precipitated out. However, slight dissolution occurred due to the nature solubility of metal hydroxide. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effect of the alkaline sulfide (Na2S+NaOH) pre-identification process on cyanide leaching performance in oxidized refractory gold-silver ores. The ore has intensive oxide, carbonate, and silicate content, and contains Au/Ag minerals containing electrum, acanthite, and silver-bearing FePbZn Sulphate-Arsenate/Hydroxide minerals together with Fe, Pb, and Zn minerals. Niğde Ulukışla refractory Au/Ag ore has 8-9 g/T gold and 170-180 g/T silver grades. In mineralogical examinations, it was found that these metals were closed in minerals such as iron oxy/oxyhydroxide, calcite, and quartz or neighboring these minerals. In the cyanide soluble process after alkali sulfide preliminary procedure at room temperature, metal extraction yields were obtained as 62% for gold and 7% for silver. It is seen that silver is adversely affected by this process compared to the direct cyanidation process. However, after the hot alkali treatment process, metal extractions improved by approximately 25% of gold and 74% of silver. This increase in yield can be considered as converting Ag-oxyhydroxide into soluble Ag forms as a result of the effect of hot alkaline sulfur leaching on the cyanide process. The most important advantage of this decomposition process is to achieve high metal extraction efficiency in lower alkali concentrations. [ABSTRACT FROM AUTHOR]

Over 14 billion tons of mine tailings are produced throughout the world each year, and this type of waste is generally stored onsite indefinitely. Alkali activation is a promising strategy for the reuse of mine tailings to produce construction materials, converting this waste stream into a value-added product. One major problem with alkali-activated mine tailings is their low durability in water (i.e., low hydrolytic stability). In this article, the influence of a mixed sodium hydroxide/sodium silicate alkali activator on the compressive strength, hydrolytic stability, and microstructure of alkali-activated materials (AAMs) were systematically investigated. XRD, FTIR, NMR, and NAD were used to investigate microstructural changes, and a water immersion test was used to show improvements in hydrolytic stability. For gold mine tailings activated with pure sodium hydroxide, the compressive strength was 15 MPa and a seven-day water immersion test caused a strength loss of 70%. With an addition of 1 M sodium silicate in the activator, the AAMs achieved a compressive strength of over 30 MPa and strength loss of only 45%. This paper proposes a mechanism explaining why the strength and hydrolytic stability of AAMs are dependent on the dosage of soluble silicate. A high dosage of sodium silicate inhibits the depolymerization of the source material, which results in a sample with less amorphous aluminosilicate gel and, therefore, lower hydrolytic stability. [ABSTRACT FROM AUTHOR]

Chemical modification is an efficient strategy for improving wood quality; however, for some fast-grown wood species unwanted shrinkage occur upon treatment with alkaline solution. This study was devised to reveal the shrinkage behavior of poplar and radiata pine woods treated with 5, 10, 15 and 20 % alkaline sodium silicate (SS) solutions. Wood treated with sodium hydroxide (SH) solution adjusting to the same pH as the specific SS solution was used as a reference sample. The weight loss, chemical components analysis, and confocal microscopy revealed that treatments with SS caused considerable reductions in hemicellulose and acid-insoluble lignin (AIL) of poplar wood up to 51 % and 21 %, respectively. In contrast, such reductions of the SS-treated radiata pine wood were only 13 % and 2 %, respectively. Consequently, shrinkage of poplar wood in the tangential- and radial-directions reached up to 22 % and 11 % respectively. However, such shrinkage for radiata pine was less than 2 % in either direction. The crystallinity index of poplar and radiata pine woods after treatment increased up to 35.3 % and 4.8 %, respectively, attributable to removal of the amorphous fraction. The scanning electron microscopy displayed that treatments had minor effect on the cell structure of radiata pine, but brought about significant collapse of poplar cells. The above results show that radiata pine is more chemically stable to alkaline treatment than poplar. [ABSTRACT FROM AUTHOR]

CO2 capture experiments were carried out in a small-scale bubble column reactor using alkaline solutions of sodium hydroxide. The results of the experiments show that a higher NaOH content in the liquid phase and elevated CO2 concentrations in the gas mixture led to a higher CO2 removal efficiency. A mathematical model was developed to describe the CO2 absorption as a function of CO2 gas inlet and OH- concentrations at low CO2 and OH- concentrations. The CO2 uptake at high OH- concentrations (high pH) was accurately predicted by the model, whereas the CO2 uptake at lower OH- concentrations could not be predicted with the same accuracy. [ABSTRACT FROM AUTHOR]

Carbonated macaw palm oil and maleinised macaw palm oil were reacted with five different amines to obtain renewable copolymers with a bio-based content greater than 80%. The polymerisation process is greener and reduces parallel reactions in the glycerol ester backbone. Polymerisation was completed in only 24 h at 120 °C. Polymers demonstrated flexible properties and were in a rubbery state at room temperature. The polymer using 1,6-hexanediamine-HDA showed hydrophobicity and could be a promising coating for wood that can be used for industrial applications. Moreover, all polymers were totally hydrolysed in a sodium hydroxide solution. [ABSTRACT FROM AUTHOR]

Patient: Female, 70-year-old Final Diagnosis: Chemical burn in the oral cavity Symptoms: Heightened salivation * intense burning sensation * oral edema Clinical Procedure: -- Specialty: Dentistry Objective: Rare disease Background: Chemical burns in the oral cavity, although rare, cause more severe tissue damage than thermal burns, continuing tissue destruction even after removing the causative substance. Prompt identification of the substance, exposure extent, time from injury to treatment, and the injured area are imperative for effective management. This report details severe oral burns in an elderly woman from accidental NaOH ingestion. Case Report: A 70-year-old female patient was presented to our hospital approximately 15 h after inadvertent consumption of approximately 20 ml of NaOH (sodium hydroxide) solution. This incident led to oral discomfort and restricted mouth opening. The ingested solution, erroneously assumed to be a beverage, was later identified as a potent alkaline substance typically employed in grease removal. Initial manifestations included intense burning sensation, oral edema, and heightened salivation, which exacerbated on the following day, adversely impacting her alimentation and verbal communication. Clinical examination disclosed extensive damage to the oral mucosa. The diagnosis encompassed a chemical burn in the oral cavity coupled with chronic gastritis. The treatment regimen comprised dietary limitations, administration of famotidine for gastric acid suppression, intravenous hydration, nutritional support, oral care with Kangfuxin liquid, and nebulization therapy. Six months after therapy, she exhibited complete recovery, with the absence of discomfort and restored normal oral functions. Conclusions: Timely and targeted treatment strategies, particularly nebulization medication and Kangfuxin liquid, are effective in managing chemical burns in the oral cavity, promoting wound healing, and preventing complications. [ABSTRACT FROM AUTHOR]

The construction of lunar surface roads is conducive to improving the efficiency of lunar space transportation. The use of lunar in situ resources is the key to the construction of lunar bases. In order to explore the strength development of a simulated lunar soil geopolymer at lunar temperature, geopolymers with different sodium hydroxide (NaOH) contents were prepared by using simulated lunar regolith materials. The temperature of the high-temperature section of the moon was simulated as the curing condition, and the difference in compressive strength between dry curing and sealed curing was studied. The results show that the high-temperature range of lunar temperature from 52.7 °C to 76.3 °C was the suitable curing period for the geopolymers, and the maximum strength of 72 h was 6.31 MPa when the NaOH content was 8% in the sealed-curing mode. The 72 h strength had a maximum value of 6.87 MPa when the NaOH content was 12% under dry curing. Choosing a suitable solution can reduce the consumption of activators required for geopolymers to obtain unit strength, effectively reduce the quality of materials transported from the Earth for lunar infrastructure construction, and save transportation costs. The microscopic results show that the simulated lunar soil generated gel substances and needle-like crystals under the alkali excitation of NaOH, forming a cluster and network structure to improve the compressive strength of the geopolymer. [ABSTRACT FROM AUTHOR]

In order to explore ideal materials with suitable excitation wavelengths, high thermal stability and good emission characteristics for phosphor-converted white light emitting diodes (pc-WLEDs), in this work, a blueish-white phosphor (λ ex = 390 nm) was realized by a new strategy of carbocations formation in ZSM-5 zeolite, which maintains the luminescence intensity at 473 K is 103% of that at room temperature. Following immersion in ethanol, water, 40 wt% sodium hydroxide solution (NaOH), and concentrated hydrochloric acid (HCl) for 120 h, the luminescence intensity was maintained at 92%, 87%, 80%, and 82% of the normal state, respectively. By packaging the sample on a near-ultraviolet (NUV) chip (390 nm), a blueish-white pc-LED was fabricated, which has a promising commercial prospect in the field of aquatic plant lighting. Meanwhile, a pc-WLED device was fabricated by combining a 390 nm NUV chip and ZSM-5 zeolite and red phosphor K 2 MgGeO 4 :Eu3+. It has an excellent property with the correlated color temperature (CCT) = 4600 K and color rendering index (CRI) = 91.5, indicating that ZSM-5 zeolite has good application prospects in the pc-WLEDs field. [Display omitted] [ABSTRACT FROM AUTHOR]

It is of interest to develop wide-temperature domain damped hydrophobic materials. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. The added bio-based phenolic resin has reticulated structure blended with butyl rubber, combined with sodium hydride activation-modified IIR. The results show that sodium hydride activated modification of DBA is introduced into the main chain structure of IIR by infrared and 1H NMR analysis. The material hydrophobic is realized by the introduction of DBA with static water contact angle of 103.5°. The addition of 10phr lignin-based phenolic resin (LPF) is compatible with IIR, and the torque can reach 7.0 N-m. The tensile elongation of the modified butyl rubber composite can reach 2400% with tensile strength up to 11.43 MPa, while the damping factor can reach 0.37 even at 70 °C. The thermal stability of the composites is enhanced with mass retention rate of 28%. The bio-based PF/NaH activation-modified butyl rubber damping material has potential applications in damping hydrophobicity with wide temperature range. [ABSTRACT FROM AUTHOR]

The paper investigates the ion-exchange resin cleaning during processing of pregnant solutions obtained by in-situ leaching. Sodium and ammonium hydroxides and AMP and Purolite ion-exchange resins are used for cleaning. Regeneration of ion-exchange resins with and without preliminary cleaning is studied herein. The efficiency analysis of described processes is based on mass spectrometry, spectrophotometry, and X-ray fluorescence of the impurity content in alkali washes. It is found that alkaline cleaning is effective for washing silicon and phosphorus. [ABSTRACT FROM AUTHOR]

Natural fiber-based composites demonstrate excellent and comparable static and dynamic mechanical properties to conventional materials, such as steel and aluminum. They also extend their applications to aeronautical, sports equipment, and marine fields. This experimental study aims to find the effect of untreated and treated Abaca-reinforced epoxy composites on the viscoelastic behavior and the optimum combinations of fiber and resin to produce better bonding efficiency. The different specimens used for this study were pure epoxy, untreated, and chemically treated composite specimens. The four weight percentages of Abaca fibers are 10%, 20%, 30%, and 40% used to prepare composite specimens. Similarly, four different sodium hydroxide (NaOH) concentrations, 4, 6, 8, and 10 wt. %/vol. %, have been used for the chemical treatment of fibers. The storage modulus of Abaca-reinforced epoxy composite specimen has been investigated with respect to temperature and fiber content. The result shows that the 30% weight fraction of fibers with chemically (8 wt. %/vol. %) treated fiber-reinforced epoxy specimen produces 41.67% higher storage modulus than the 10% weight fraction of fibers content of composite specimens. Fourier-Transform Infrared Spectroscopy (FTIR) broad transmittance has been used to distinguish the raw and chemically treated fibers. FTIR results reveal the removal of functional groups after NaOH treatment. [ABSTRACT FROM AUTHOR]

The reactions of pyrethrin I, cinerin I and jasmolin I with sodium hydroxide in ethanol afforded an approximately 1:1 ratio of two respective cyclopentadienone dimers, isolated in good yield. A combination of one-dimensional and two-dimensional NMR spectroscopic studies allowed determination of the structure and stereochemistry of the dimers. The dimers are formed by cycloaddition reactions of the less substituted alkene of the cyclopentadienone, and by regioisomeric endo transition states. Density functional theory calculations were in accord with the experimental findings showing the products formed by ambimodal transition states. One such transition state led to two initial products with the less stable product undergoing facile conversion to the other more stable, experimentally observed product. These studies clarify the structures of the altered pyrethrolone reported by Staudinger and Ruzicka in 1924. On treatment with base, the natural pyrethrins pyrethrin I, cinerin I and jasmolin I undergo elimination to transient cyclopentadienones that dimerise to afford regioisomeric endo cycloadducts. (Image credit: J. H. Ryan.) [ABSTRACT FROM AUTHOR]

Geopolymers (GPs) are gaining prominence due to their low carbon emissions and sustainable attributes. However, one challenge with GPs, particularly those made with ground granulated blast furnace slag (GGBFS), is their significant shrinkage during the geopolymerization process, limiting its practical applicability. This study focuses on how the substitution ratio of metakaolin (MK) and the concentration of sodium hydroxide (NaOH) in the activator can influence the shrinkage and strength of a GGBFS-based GP. The experimental approach employed a 3 × 3 parameter matrix, which varied MK substitution ratios (0%, 50%, and 100%) and adjusted the NaOH concentration (6 M, 10 M, and 14 M). The results revealed that increasing MK substitution, particularly with 6 M NaOH activation, reduced the GP shrinkage but also diminished compressive strength, requiring higher NaOH concentrations for strength improvement. Statistical tools, including analysis of variance (ANOVA) and second-order response surface methodology (RSM), were employed for analysis. ANOVA results indicated the significant impacts of both the MK content and NaOH concentration on compressive strength, with no observable interaction. However, the shrinkage exhibited a clear interaction between MK content and NaOH concentration. The RSM model accurately predicted compressive strength and shrinkage, demonstrating a high predictive accuracy, for which the coefficients of determination (R2) were 0.99 and 0.98, respectively. The model provides a reliable method for determining the necessary compressive strength and shrinkage for GGBFS-based GP based on MK substitution and NaOH concentration. Within the optimization range, the RSM model compared with experimental results showed a 6.04% error in compressive strength and 0.77% error in shrinkage for one interpolated parameter set. This study establishes an optimized parameter range ensuring a GP performance that is comparable to or surpassing OPC, with a parameter set achieving a compressive strength of 34.9 MPa and shrinkage of 0.287% at 28 days. [ABSTRACT FROM AUTHOR]

Ironstone surrounds many fossils and has a hardness that provides a significant challenge to fossil conservators globally. There are various forms of ironstone, with the carbonate forms of siderite and silicates most often containing vertebrate fossils and potentially preserved soft tissues. The ironstone itself is much harder than the fossils preserved within, leading to the mechanical preparation of the fossils––typically using pin vises or airscribes––being time-consuming and presenting the risk of damage. Existing chemical methods for softening ironstone to prepare the fossils have varied success and also pose a risk of damaging the fossil itself. Here we show that carbonic acid can soften ironstone without damaging permineralized bone or potentially preserved soft tissues. Carbonic acid treatments reduced the hardness of ironstone without causing any significant change in hardness, color, chemical composition, or weight to permineralized ceratopsian bones or a modern cervid bone that retained nonmineralized internal tissues. In addition, we found that solutions of sodium hydroxide and hydrogen peroxide were viable for softening ironstone to remove from the permineralized bone when preserved soft tissue recovery is not a priority. The treatments proposed in this study are important as they are applicable to a range of preparation scenarios, are cost-efficient, are relatively safe to handle, and cause no damage to permineralized fossil bones. Putting these methods into practice can lead to more efficient and safe preparation of fossils in ironstone. [ABSTRACT FROM AUTHOR]

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. This article investigates the application and approaches of a unique form of high-frequency traveling-wave magnetic fields to low-conductivity liquids with conductivity ranging from 1 to 102 S/m. Experiments were conducted using four representative electrolytic solutions commonly employed in the chemical industry: sulfuric acid (H2SO4), sodium hydroxide (NaOH), sodium chloride (NaCl), and ionic liquid ([Bmim]BF4). The investigation focuses on the impact of high-frequency magnetic fields on these solutions at the optimal operating point of the system, considering the effects of Joule heating. The findings reveal that the high-frequency traveling magnetic field exerts a significant volumetric force on all four low-conductivity liquids. This technology, characterized by its non-contact and pollution-free nature, high efficiency, large driving volume, and rapid driving speeds (up to several centimeters per second), also provides uniform velocity distribution and notable thermal effects. It holds considerable promise for applications in the chemical industry, metallurgy, and other sectors where enhanced three-phase transfer processes are essential. [ABSTRACT FROM AUTHOR]

This article discusses a new method for synthesizing esters and carboxylic acids using copper-catalyzed carbonylative coupling reactions. The traditional methods for synthesis often involve harsh conditions and hazardous chemicals, but this new approach offers a more efficient and environmentally friendly alternative. The authors optimized the reaction conditions and demonstrated the scope and limitations of the process. The document also provides detailed procedures and characterization data for specific compounds synthesized using this method. Further research is being conducted to expand the scope of this method. [Extracted from the article]

An effective and novel synthesis of β-keto amides had been developed by NaOH promoted hydrolysis of α-oxo ketene-N, S-acetals. It was found that the hydrolysis of α-oxo ketene-N, S-acetals in the presence of 2 equivalent of NaOH in refluxing EtOH (95%) gave β-keto amides in excellent yields. The uses of toxic and harmful amines as well as the prepurification of these nucleophilic reagents were not required in the hydrolysis reaction. The method can extend to gram scale. [ABSTRACT FROM AUTHOR]

The tribological behavior of Ultra-High Molecular Weight Polyethylene (UHMWPE) composites, reinforced with nano-sized Zinc Oxide (ZnO) particles, was systematically investigated under both dry and wet conditions. Composites were fabricated via hot compression molding, ensuring homogeneous nanoparticle distribution and effective bonding. Wear rates in dry conditions were assessed using a pin-on-disc apparatus, with a composite pin against a 63 HR EN31 steel disc, while wet tribology tests employed distilled water as a lubricant. Post-experimental Scanning Electron Microscopy (SEM) analyses revealed distinct wear mechanisms between the two environments. Under dry conditions, an increase in wear rates and frictional forces was observed for the composites, whereas the introduction of water as a lubricant significantly reduced wear rates in wet conditions. The presence of nano ZnO was found to enhance the mechanical properties and wear resistance of UHMWPE, particularly in the presence of lubrication. When subjected to a 100rpm and 10N load, the UHMWPE composite with a 10wt% ZnO filler exhibited a marked reduction in weight loss (1.1mg) in comparison to the unfilled UHMWPE (5.1mg). This improvement was sustained at elevated speeds and loads, indicating that higher filler concentrations correlate with improved wear resistance. Wet wear testing further demonstrated the advantageous role of nano ZnO, with UHMWPE composites incurring less weight loss than their unfilled counterparts. The hydrophobic nature of nano ZnO was instrumental in reducing wear under lubricated conditions. These findings underscore the potential for nano ZnO reinforced UHMWPE composites in applications demanding high wear resistance, such as in biomedical implants and automotive components. Moreover, the hydrophobic properties of nano ZnO suggest additional benefits in wet environments. Future work should focus on optimizing nano ZnO loadings for maximum wear resistance and exploring the integration of other reinforcing agents to create composites with multifaceted functional attributes. [ABSTRACT FROM AUTHOR]

Simple Summary: The possibility of pain occurring in animals is often accepted if various criteria are fulfilled. These criteria include prolonged grooming or rubbing at the site of a wound or tissue damage, or other behaviour involving the site of damage. We also expect to see a reduction in such activities if a local anaesthetic is applied. Here, we report on an experiment that applied caustic soda, a known irritant in humans, to one eyestalk of the glass prawn. This caused immediate escape responses and then nipping and picking at the treated eyestalk rather than at the untreated eyestalk. Prior application of a local anaesthetic reduced the amount of directed behaviour. However, the local anaesthetic also appeared to be an irritant as it too caused immediate escape responses and directed behaviour to the eyestalk. The results provide further support to the idea that these animals can experience pain. Acceptance of the possibility of pain in animals usually requires that various criteria are fulfilled. One such criterion is that a noxious stimulus or wound would elicit directed rubbing or grooming at the site of the stimulus. There is also an expectation that local anaesthetics would reduce these responses to damage. These expectations have been fulfilled in decapod crustaceans but there has been criticism of a lack of replication. Here, we report an experiment on the effects of a noxious chemical, sodium hydroxide, applied to one eyestalk of the glass prawn. This caused an immediate escape tail-flick response. It then caused nipping and picking with the chelipeds at the treated eyestalk but much less so at the alternative eyestalk. Prior treatment with benzocaine also caused an immediate tail-flick and directed behaviour, suggesting that this agent is aversive. Subsequently, however, it reduced the directed behaviour caused by caustic soda. We thus demonstrated responses that are consistent with the idea of pain in decapod crustaceans. [ABSTRACT FROM AUTHOR]

We designed and characterized chitosan–caseinate fibers processed through wet spinning for biomedical applications such as drug delivery from knitted medical devices. Sodium caseinate was either incorporated directly into the chitosan dope or allowed to diffuse into the chitosan hydrogel from a coagulation bath containing sodium caseinate and sodium hydroxide (NaOH). The latter route, where caseinate was incorporated in the neutralization bath, produced fibers with better mechanical properties for textile applications than those formed by the chitosan–caseinate mixed collodion route. The latter processing method consists of enriching a pre-formed chitosan hydrogel with caseinate, preserving the structure of the semicrystalline hydrogel without drastically affecting interactions involved in the chitosan self-assembly. Thus, dried fibers, after coagulation in a NaOH/sodium caseinate aqueous bath, exhibited preserved ultimate mechanical properties. The crystallinity ratio of chitosan was not significantly impacted by the presence of caseinate. However, when caseinate was incorporated into the chitosan dope, chitosan–caseinate fibers exhibited lower ultimate mechanical properties, possibly due to a lower entanglement density in the amorphous phase of the chitosan matrix. A standpoint is to optimize the chitosan–caseinate composition ratio and processing route to find a good compromise between the preservation of fiber mechanical properties and appropriate fiber composition for potential application in drug release. [ABSTRACT FROM AUTHOR]

A hollow fiber supported liquid membrane (HFSLM) was used to extract and eliminate glufosinate ammonium from aqueous solution using TOA (tri-n-octylamine) in hexane and sodium hydroxide (NaOH) as carrier and stripping phase, respectively. Maximum extraction (∼76%) and stripping (∼75%) were achieved by feed solution at pH 1.0, temperature 60 °C, TOA concentration 6% (v/v) and NaOH concentration 1.0 M. The developed mathematical model exhibited high precision when predicting the concentration of glufosinate ammonium in raffinate solution and extraction percentage under different feed flow rates, with correlation coefficient (R²) 0.9863. [ABSTRACT FROM AUTHOR]

The current study presents an investigation into the optimal content determination of the mix parameters in their acceptable ranges through fresh, mechanical, and durability characteristics in ground granulated blast furnace slag (GGBFS) based self-compacting geopolymer concrete (SCGC) cured under ambient temperature. Ordinary portland cement (OPC) based self-compacting concrete (SCC) was prepared as a control concrete. Both the M25 SCGC and SCC were characterized through fresh property tests satisfying the flowability, passing ability, and segregation resistance; mechanical tests by both nondestructive and destructive tests; and durability tests through water absorption, sorptivity, acid attack, sulfate attack; and rapid chloride permeability test (RCPT). The prime mix parameters considered in SCGC with their variation ranges were molar concentration of sodium hydroxide (10M, 12M, 14M, 16M), sodium silicate to hydroxide ratio (1.5, 2.0, 2.5, 3.0), superplasticizer (SP) dosage (5%, 6%, 7%, 8%), and percentage of extra water (EW) (15%, 18%, 21%, 24%). The results of SCGC were compared with the control SCC and discussed. The mix parameter optimal values derived from all the fresh and hardened concrete properties were a 12M concentration of sodium hydroxide, sodium silicate to hydroxide ratio of 2.5, SP dose of 7%, and EW percentage of 21%. SCGC thus prepared is stable, workable, and exhibits superior properties to OPC-based concrete to promote sustainable development. The current study estimates the optimal quantity of mix parameters, i.e., 12M NaOH, AAS ratio of 2.5, 7% SP, and 21% EW to produce ground granulated blast furnace slag (GGBFS)-based self-compacting geopolymer concrete (SCGC) cured under ambient temperature. The SCGC-optimized mix-parametric values are evaluated based on the mix materials whose physical and chemical properties are declared in the manuscript. The cementless concrete thus prepared is GGBFS based, which is an industrial byproduct, yielding sustainable concrete. Under ambient temperature, the SCGC can be cured, which is practically beneficial for the in situ construction work. The self-compacting capability of SCGC involves minimal energy in producing a dense, smooth concrete surface, reducing both the construction period and cost involvement. Being a stable workable concrete, its nonsegregation nature makes it homogeneous with minimal entrapped air. The reduced permeability nature renders it a larger insulating potential. Concerning OPC-based concrete, SCGC has larger mechanical and durability characteristics, making it a better choice. Thus, the SCGC has a huge potential in the global construction sector and is practically applicable. [ABSTRACT FROM AUTHOR]

The article presents research on the purification process of pyrolysis gas from hydrogen sulfide. To our best knowledge, similar studies have not been performed yet on a real pyrolysis gas obtained from waste tyres, which contains huge amounts of hydrogen sulfide - average 3.6% (up to 5.1% at 420 °C). Different sorbents were tested, among them sodium hydroxide, zinc oxide, and manganese oxide. NaOH in concentration 0.05 M appeared to be the most efficient, showing ∼94% H 2 S removal efficiency under the conditions studied. ZnO features a better efficiency of H 2 S removal from hot gas (∼55%) than MnO. Furthermore, the combination of ZnO and a 0.05 M solution of NaOH was studied. The detailed composition of the pyrolysis gas was performed, too. The main components and sulfur-containing compounds, such as methyl mercaptan, carbonyl sulfide, and ethyl mercaptan, concentrations were measured. Predominantly, the gas consists of methane, hydrogen, ethane, ethene, carbon dioxide, iso-butane, and hydrogen sulfide. Aggregated concentrations of the above-mentioned exceed 80% of the gas, which makes it a very promising gaseous fuel. • Pyrolysis gas with a high heating value – approx. 34 MJ/m3 – contains significant amounts of hydrocarbons and hydrogen. • Pyrolysis gas features high concentrations of sulfur-containing compounds, mainly hydrogen sulfide with average conc. 3.6%. • Pyrolysis gas is as a valuable gaseous fuel, but it needs pre-treatment focused on desulfurization. • Tested metal oxides can significantly reduce the concentration of hydrogen sulfide in the gases (∼55% - ZnO; 38% - MnO). • Sodium hydroxide (NaOH) features the best potential for hydrogen sulfide removal, reaching about 94% removal efficiency. [ABSTRACT FROM AUTHOR]

Phosphine-stabilized gold clusters are an important subgroup of metalloid gold cluster compounds and are important model compounds for nanoparticles. Although there are numerous gold clusters with different phosphine ligands, the effect of phosphine on cluster formation and structure remains unclear. While the linear alkyl-substituted phosphine gold chlorides result in a Au32 cluster, the bulky tBu3P leads to a Au20 cluster. The reduction of (iPr2nBuP)AuCl, with the steric demand of the phosphine ligand between the mentioned phosphines, results in the successful synthesis and crystallization of a new metalloid gold cluster, Au30(PiPr2nBu)12Cl6. Its structure is similar to the Au32 cluster but with two missing AuCl units. The UV/Vis studies and quantum chemical calculations show the similarities between the two clusters and the influence of the phosphine ligand in the synthesis of metalloid gold clusters. [ABSTRACT FROM AUTHOR]

Sudan I was determined using a switchable-hydrophilicity solvent (SHS) followed by ultraviolet/visible spectrophotometric detection at 445.0 nm in a simple, fast, sensitive, and low-cost method. The optimum switchable-hydrophilicity solvent liquid-liquid microextraction (SHS-LLME) conditions were achieved with 600 µL of octylamine and 600 µL of 10.0 M sodium hydroxide in 20.0 mL of the sample. Limits of detection ranged from 0.009 to 0.021 µg mL−1. The coefficients of determination (R2) of the calibration graphs were higher than 0.9983 and relative standard deviations were below 8.6%. Enrichment factors ranged between 5.29 and 12.89. The proposed method was applied to spices with recoveries (%RR) between 92.5% and 104.4%. [ABSTRACT FROM AUTHOR]

Co-generation of hydrogen with value-added by-products is a promising route for affordable low-carbon hydrogen. This work presents a system for and a technoeconomic analysis of hydrogen with the co-generation of chlorine and sodium hydroxide from waste brine. The system uses a conceptual triple-junction gallium arsenide (3-J GaAs)-based photoelectrochemical (PEC) reactor at high solar concentrations (50–500x). The base case of 200x solar concentration results in a solar-to-chemical (SCE) efficiency of 15% and a levelized cost of hydrogen (LCOH) production of $15.76/kgH2. Revenue from by-products ($45.36/kgH2) is critical for offsetting the operating costs, with sodium hydroxide constituting 64% of total by-product revenue. The sensitivity analysis showed that under favorable combinations of the key variables (sodium hydroxide price, waste brine pretreatment price, and PEC replacement lifetime) PEC hydrogen generation from waste brine would be viable and have prices reaching $0.78/kgH2. • Analysis of concentrated triple-junction photoelectrochemical hydrogen production. • Desalination waste brine as feed with co-production of chlorine and sodium hydroxide. • Results show that solar hydrogen can be reduced below the U.S. Department of Energy target of $1/kg H2. • Reactor lifetime, concentration factor, and co-product prices have economic leverage. [ABSTRACT FROM AUTHOR]

The reaction of (1,2-dibromoethyl)(diphenyl)phosphine oxide with CH-acids (acetylacetone, acetoacetic ester, and malonic ester) in the presence of sodium hydroxide has afforded diphenylphosphoryl-substituted cyclopropanes in high yield. It has been shown that the reaction of (1,2-dibromoethyl)(diphenyl)phosphine oxide with primary arylamines leads to the formation of bis(phosphine oxides), in contrast to alkylamines which lead to phosphoryl-substituted aziridines. [ABSTRACT FROM AUTHOR]

Sodium stannate has numerous applications, including electroplating, tin alloy, catalysts, precursor to flame retardants, and also can be used as solid electrolytes and electrode materials in emerging battery systems. The primary method for producing sodium stannate typically involves the reaction between tin metal and sodium hydroxide solution. However, the procedure exhibited several limitations, such as high energy consumption, a long process flow for the production of metallic tin, as well as the release of potentially hazardous gases. Therefore, the present study focused on synthesizing sodium stannate from cassiterite minerals through alkaline pressure leaching, followed by crystallization. The main aim of this study was to examine the effect of various leaching process parameters, such as sodium hydroxide concentration, leaching temperature, and leaching time on the improvement of tin dissolution. The results showed that the alkaline pressure leaching process can successfully produce sodium stannate from the cassiterite mineral. The optimum parameters for alkaline pressure leaching to produce sodium stannate from cassiterite have been determined: temperature of 150°C, sodium hydroxide concentration of 4 mol/L, and duration of 240 minutes. [ABSTRACT FROM AUTHOR]

Kenaf fiber is gaining prominence because of its ability as a natural-based reinforced material in advanced composites. However, kenaf contains a hygroscopic natural waxy substance that covers the fiber layer, providing a low surface tension and preventing strong bonding with the polymer matrix. The goal of this study is to optimize the blending parameters of kenaf fiber-reinforced epoxy composites by alkali treatment concentration, length, and fiber-matrix loading using central composite design. The maximum tensile strength was obtained at 6.03 wt% of NaOH concentration, fiber loading of 26.02 wt%, and fiber length at 7.39 mm, which showed a strong correlation between experimental and predicted values. The analysis of variance function model indicated that fiber length, sodium hydroxide concentration, and fiber loading all play important roles in mechanical properties of composites. Based on the fracture surface observations, kenaf fiber composite strength was closely related to bonding at fiber-matrix interfaces. The most common failure modes in the samples were voids, matrix fracture, fiber breakage, weak bonding, and fiber pull-out. [ABSTRACT FROM AUTHOR]

Rice husks, a byproduct of rice milling, were used to develop composite boards. Different processing methods, grinding, and treating with sodium hydroxide (NaOH), were adopted to improve the bonding and mechanical performance. NaOH solution was prepared at 5% (wt/v) concentration. The effect of different adhesives, phenol formaldehyde (PF), and polymeric diphenylmethane diisocyanate (pMDI), was evaluated. Rice husks mixed with resin were hot pressed to the target density of 768 kg/m3 and thickness of 12.7 mm. Specimens cut from these flat panels were submitted to bending, internal bond, water absorption, and thickness swelling tests. Results revealed that chemical treatment with NaOH significantly improved fiber-to-fiber bonding of rice husks. Internal bond strength of specimens made from chemically treated rice husks increased at least 1000% compared to others. Considering the mechanical properties and water uptake, rice husk boards fabricated with unprocessed rice husks and pMDI showed a better performance. [ABSTRACT FROM AUTHOR]

European paper mills are currently facing the question of whether recovered paper, their main raw material, will be available in sufficient quantities and an acceptable quality in the future. An alternative to recovered paper or wood fiber is the use of agricultural residues such as wheat straw. Sodium carbonate-based straw pulping processes have the advantage of not requiring recausticizing for chemical recovery, which reduces investment and operating costs. With the addition of oxygen, delignification can be significantly improved to provide pulps suitable for bleaching. This study compares the pulping of wheat straw using sodium carbonate, sodium carbonate + oxygen, and sodium carbonate + sodium hydroxide + oxygen. Pulping parameters such as temperature, retention time, and chemical charge were varied, and their influence on pulp properties was studied. The use of sodium carbonate alone produced pulps with high yields of up to 72% and comparably high burst and compressive strength. The addition of oxygen and small amounts of sodium hydroxide produced pulps with a high initial brightness of 42 %ISO and a low kappa number (18), still at high pulp yields of 62%. These pulps were two-stage bleached to achieve brightness levels of up to 73 %ISO. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2‐chloroquinoxaline‐3‐carbonitrile 1. The compound 1 was subjected to a reaction with selenium metal in the presence of NaBH4 as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3‐cyanoquinoxaline‐2‐selenolate, which was subsequently reacted with α‐halogenated carbonyl compounds in situ. This reaction produced a series of newly synthesized 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐substituents. Ethyl 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9. This salt was then refluxed with acetic anhydride to produce oxazinone compound 10. The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3‐b]quinoxaline derivative 11. Compound 11 was then chlorinated using phosphorous oxychloride to give the corresponding chlorocompound. [ABSTRACT FROM AUTHOR]

Various purification methods have been developed to improve local salt quality, with the NaCl content above 94%. Bentonite is one of the materials used as binder impurities in purification. The purpose of the study was to synthesize a modified bentonite using an alkaline solution, which includes sodium hydroxide (NaOH) and potassium hydroxide (KOH) with various concentrations (1 M, 1.5 M, 2 M, and 2.5 M) and determined levels of Na+, Ca2+ and Mg2+ metals using AAS. The bentonite and activating agent 1 M (1:10) were stirred for three hours. Then, the bentonite was dried for two hours in an oven at 110 °C. The activated bentonite was dried for four hours at 170 °C. The activated bentonite was characterized using XRD, FTIR, and SEM. The basal spacing d001 on the diffractogram bentonite was significantly unaffected by alkaline activation. FTIR analysis represents the stretching vibration of -OH shifts towards a lower wavenumber. Alkaline activation reduced impurities from bentonite and increased the pore surface's porosity. NaCl levels in people's salt increased after being activated using alkaline. The increase in Na+ levels was followed by a decrease in Ca2+ and Mg2+ contents. KOH-activated bentonite had a higher NaCl level than NaOHactivated bentonite. [ABSTRACT FROM AUTHOR]

Reactive dyes such as Remazol Yellow FG are contaminants that are difficult to degrade in the environment. The adsorption method is an alternative to overcome this problem. Corn husk and eggshells can be adsorbents in adsorption. Corn husk contains an organic compound called cellulose, while eggshells have the main component of calcium carbonate. Corn husks and eggshells have the potential to be adsorbents with different characteristics. This research aimed to determine the optimum conditions for the combined adsorbent of corn husks and eggshells, which included composition comparison, contact time, pH, and application in dye waste. The interactions between Remazol Yellow FG dye in solution and combined adsorbent were conducted in batch method. Based on the research results, the optimum composition of corn husks and eggshells was 1:2, with an optimum contact time of 80 minutes at a pH of 2, resulting in an adsorption capacity of 0.559 mg/g, with an adsorption percentage of 33.95%. Adsorption of Remazol Yellow FG in sewage using combined adsorbents under optimal conditions obtained an adsorption capacity of 36.6579 mg/g with an adsorption percentage of 27.87%. The results demonstrate that the combined adsorbent of corn husks and eggshells is a potentially useful for removing Remazol Yellow FG dye from textile wastewater. [ABSTRACT FROM AUTHOR]

Tungsten (W) isotopes are useful tools in geological and cosmochemical research, but the chemical separation of W is cumbersome for high‐precision measurement. Here, a novel alkali (sodium hydroxide, NaOH) precipitation method for separation and purification of W in geological samples is described, which simplifies the chemical procedure. The amphoteric character of W is exploited to separate it from most matrix elements in alkaline conditions. Subsequently, TEVA resin was applied to further purify W for measurements using a multi‐collector inductively coupled plasma‐mass spectrometer. Importantly, the introduction of a certain amount of Na in the W analyte can increase the signal intensity by approximately 1.6 times, which may be caused by Coulomb fission. Such Na‐triggered signal enhancement reduces the test portion mass required for analysis. Our results show that the Alfa Aesar W standard solution and geological reference materials JB‐3, BCR‐2 and BHVO‐2 yield 182W/184W ratios consistent with previously reported values within uncertainty. Repeated measurement of the Alfa Aesar W standard solution shows that the intermediate precision of 182W/184W was better than 5 ppm (2s), which is sufficient to identify subtle 182W isotope variations in terrestrial and extra‐terrestrial samples. Above all, the alkali precipitation method in this study optimises the experimental process and mass spectrometric analysis. [ABSTRACT FROM AUTHOR]

Today, concrete is the most widely used building material. Cement production releases about 7% of carbon dioxide gas into the atmosphere and increases greenhouse gases, so it seems necessary to use an alternative to Portland cement. In recent years, geopolymers have been considered a suitable and environmentally friendly alternative to conventional Portland cement. Geopolymer concrete can be made from different sources of alumina silicate. The main goal of this experimental research is to improve the properties of physical resistance and durability of geopolymer concrete, such as carbonation, chloride ion penetration and water absorption, in order to produce sustainable materials and replace ordinary cement. It has been determined that with the concentration of the alkaline solution of 12 M and the curing temperature of 90 degrees Celsius, the properties of mechanical resistance, impact resistance (energy absorption) and durability of geopolymer concrete are improved. Also, the results show that if alkaline solutions are combined, the sample containing 80% NaOH and 20% KOH has better mechanical properties, durability and higher modulus of elasticity than other cases. Also, in terms of the correlation matrix of the modulus of elasticity (percentage of compliance with the common concrete regulations), the best results are related to the T-N80K20 mixing design with concentrations of 8 and 12 M and at curing temperature of 90 degrees Celsius with the CEB regulations, and at a curing temperature of 25 °C was obtained according to ACI 365 and ACI 318 regulations. [ABSTRACT FROM AUTHOR]