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Porous aluminum alloys are widely used for lightweight structural materials such as marine structures, energy absorbers, and buoyant components. However, the conventional foaming agent TiH2 presents limitations such as high cost and elevated decomposition temperatures, which increase manufacturing costs and restrict industrial applicability. In addition, the utilization of recycled raw materials such as aluminum machining chips has emerged as an important challenge in material development for resource efficiency and sustainability. To address these issues, porous aluminum alloys were fabricated in this study using recycled A356 aluminum chips by incorporating TiH2 and a low-cost alternative foaming agent, Na2B4O7·10H2O (borax), either individually or in combination. The effects of foaming agent content (1, 1.5, and 3 wt.%) on pore characteristics, microstructure, hardness, and corrosion resistance were systematically investigated. TiH2 induced an increase in porosity due to hydrogen generation and also promoted grain refinement, which contributed to the improvement of hardness and corrosion resistance, while Na2B4O7·10H2O exhibited effective pore formation and hardness improvement at 1–1.5 wt.% but tended to deteriorate corrosion resistance as its content increased. In particular, combined addition of both agents at 1.5 wt.% showed excellent pore formation and corrosion resistance properties, with a relatively high pore area fraction (2.38%), porosity (27.0%), SDAS (48.1 ± 4.8 µm), hardness (59.35 ± 6.4 HV), corrosion potential (−1.039 V), pitting potential (−0.709 V), and corrosion current density (4.956 μA/cm2). This study demonstrated that Na2B4O7·10H2O (borax) foaming agent can be an economic alternative to TiH2, and shows that the performance of porous aluminum alloys can be effectively improved by optimizing the combination of recycled raw materials and foaming agents.

This article applies nuclear magnetic resonance technology to the study of boron-containing traditional Chinese medicine, in order to explore the morphological evolution of boron elements in traditional Chinese medicine. Borax is a traditional Chinese medicine with anti-corrosion, anti-inflammatory, antibacterial, and anticonvulsant effects. It is made by boiling, removing stones, and drying borax minerals like borate salts. This article introduces an [sup.11]B nuclear magnetic resonance method for identifying and characterizing boron-containing compounds in TCM. We applied this technology to borax aqueous solutions in different chemical environments and found that with boron mixed in the form of SP[sup.2] hybridization in equilateral triangles and SP[sup.3] hybridization in equilateral tetrahedra, the pH changes in alkaline environments significantly affected the ratio of the two. At the same time, it was found that in addition to the raw material peak, boron signals of other boron-containing compounds were also detected in 20 commercially available boron-containing TCM preparations. These new boron-containing compounds may be true pharmaceutical active ingredients, and adding them directly to the formula can improve quality and safety. This article describes the detection of [sup.11]B NMR in boron-containing traditional Chinese medicine preparations. It is simple, non-destructive, and can provide chemical fingerprint studies for boron-containing traditional Chinese medicine.

Since cleaning of artworks may cause undesirable physicochemical alterations and is a nonreversible procedure, it is mandatory to adopt the proper cleaning procedure. Such a procedure should remove undesired materials whilst preserving the original surface. In this regard, numerous gels have been developed and exploited for the cleaning of various artwork surfaces. Lately, agarose (AG) and polyvinyl alcohol-borax (PVA-B) hydrogels have been widely employed as cleaning tools by conservators. Both hydrogels show some limitations in specific cleaning practices. In this work, we investigated the influence of including increased levels of agarose into PVA-B systems. For this reason, we performed a detailed characterization on the double network (DN) hydrogel including the chemical structure, the liquid phase retention, the rheological behavior, and the self-healing behavior of various PVA-B/AG double network hydrogels. These new hydrogels revealed better properties than PVA-B hydrogels and obviated their limitations. The inclusion of AG into PVA-B systems enhanced the liquid retention capacity, shape-stability, and mechanical strength of the blend. Furthermore, AG minimized the expelling/syneresis issue that occurs when loading PVA-B systems with low polarity solvents or chelating agents. The resultant double network hydrogel exhibits relevant self-healing properties. The PVA-B/AG double network is a new and useful cleaning tool that can be added to the conservators’ tool-kit. It is ideal for cleaning procedures dealing with porous and complex structured surfaces, vertical surfaces and for long time applications.

This paper elucidates the influence of borax decahydrate addition on the flexural and thermal properties of 10 mm thin fly ash/ladle furnace slag (FAS) geopolymers. The borax decahydrate (2, 4, 6, and 8 wt.%) was incorporated to produce FAB geopolymers. Heat treatment was applied with temperature ranges of 300 °C, 600 °C, 900 °C, 1000 °C and 1100 °C. Unexposed FAB geopolymers experienced a drop in strength due to a looser matrix with higher porosity. However, borax decahydrate inclusion significantly enhanced the flexural performance of thin geopolymers after heating. FAB2 and FAB8 geopolymers reported higher flexural strength of 26.5 MPa and 47.8 MPa, respectively, at 1000 °C as compared to FAS geopolymers (24.1 MPa at 1100 °C). The molten B2O3 provided an adhesive medium to assemble the aluminosilicates, improving the interparticle connectivity which led to a drastic strength increment. Moreover, the borax addition reduced the glass transition temperature, forming more refractory crystalline phases at lower temperatures. This induced a significant strength increment in FAB geopolymers with a factor of 3.6 for FAB8 at 900 °C, and 4.0 factor for FAB2 at 1000 °C, respectively. Comparatively, FAS geopolymers only achieved 3.1 factor in strength increment at 1100 °C. This proved that borax decahydrate could be utilized in the high strength development of thin geopolymers.

Borax-PVA hydrogels with excellent mechanical properties are prepared by simple physical mixing of polyvinyl alcohol (PVA, thickener) and borax (cross-linking agent) at room temperature. The resulting hydrogel is a three-dimensional structure composed of boric ester bonds as physical crosslinking points. Thus, the spatial structure, swelling properties, viscoelastic properties, tensile properties, and self-healing properties of hydrogels with different ratios of borax and PVA are studied. XRD confirmed that the hydrogels have similar structures near 2 θ values of 10 and 20. The microstructure of the hydrogel is confirmed by SEM and TEM. With an increase of borax mass fraction, the pore structure and morphology of hydrogel are more ordered, with substantial quantities of water immobilized within their three-dimensional structure. The viscoelastic properties and tensile properties showed that when the mass fraction of borax is 5%, the storage modulus and compressive stress of the hydrogel are the highest, reaching 100 Pa and 5.6 kPa, respectively. In addition, through physical and chemical stimulation (heating and varying pH, respectively), the hydrogels also showed reversible gel–sol conversion characteristics, indicating that the boric ester bonds have self-healing properties. Highlights The Borax-PVA hydrogels with excellent mechanical properties are prepared by simple physical mixing of polyvinyl alcohol and borax at room temperature. The Borax-PVA hydrogel is a three-dimensional structure composed of boric ester bonds as physical crosslinking points. The Borax-PVA hydrogels showed reversible gel–sol conversion characteristics, indicating that the boric ester bonds have self-healing properties.

The purpose of this study is to identify natural indicators that can be used to test the qualitative presence of formalin and borax. The results of this qualitative test can be used for student learning in schools, especially for harmful additive substances in food. Qualitative test using a drop test. Formalin test using extract flower of ribose ruellia, hibiscus rosa-sinensis L and Impatiens L balsamina, while for borax test using ruellia simplex, plumeria rubra, portulaca grandiflora and curcuma longa. Based on the results of the research that has been done, the extract can be used to determine the presence of borax and formalin with a drop test.

Surface terminations profoundly influence the intrinsic properties of MXenes, but existing terminations are limited to monoatomic layers or simple groups, showing disordered arrangements and inferior stability. Here we present the synthesis of MXenes with triatomic-layer borate polyanion terminations (OBO terminations) through a flux-assisted eutectic molten etching approach. During the synthesis, Lewis acidic salts act as the etching agent to obtain the MXene backbone, while borax generates BO 2 − species, which cap the MXene surface with an O–B–O configuration. In contrast to conventional chlorine/oxygen-terminated Nb 2 C with localized charge transport, OBO-terminated Nb 2 C features band transport described by the Drude model, exhibiting a 15-fold increase in electrical conductivity and a 10-fold improvement in charge mobility at the d.c. limit. This transition is attributed to surface ordering that effectively mitigates charge carrier backscattering and trapping. Additionally, OBO terminations provide Ti 3 C 2 MXene with substantially enriched Li + -hosting sites and thereby a large charge-storage capacity of 420 mAh g −1 . Our findings illustrate the potential of intricate termination configurations in MXenes and their applications for (opto)electronics and energy storage. MXenes with borate polyanion terminations are synthesized using a flux-assisted eutectic molten etching approach. These triatomic-layer terminations empower MXenes with considerably improved charge transport and charge storage capabilities.

Laser-induced graphene (LIG) is as a promising material for flexible microsupercapacitors (MSCs) due to its simple and cost-effective processing. However, LIG-MSC research and production has been centered on non-sustainable polymeric substrates, such as polyimide. In this work, it is presented a cost-effective, reproducible, and robust approach for the preparation of LIG structures via a one-step laser direct writing on chromatography paper. The developed strategy relies on soaking the paper in a 0.1 M sodium tetraborate solution (borax) prior to the laser processing. Borax acts as a fire-retardant agent, thus allowing the laser processing of sensitive substrates that other way would be easily destroyed under the high-energy beam. LIG on paper exhibiting low sheet resistance (30 Ω sq −1 ) and improved electrode/electrolyte interface was obtained by the proposed method. When used as microsupercapacitor electrodes, this laser-induced graphene resulted in specific capacitances of 4.6 mF cm −2 (0.015 mA cm −2 ). Furthermore, the devices exhibit excellent cycling stability (> 10,000 cycles at 0.5 mA cm −2 ) and good mechanical properties. By connecting the devices in series and parallel, it was also possible to control the voltage and energy delivered by the system. Thus, paper-based LIG-MSC can be used as energy storage devices for flexible, low-cost, and portable electronics. Additionally, due to their flexible design and architecture, they can be easily adapted to other circuits and applications with different power requirements. Graphical Abstract

Cotton (Gossypium hirsutum L.) is responsive to boron (B) fertilization when there is low soil availability, but the best source and rate to be used and whether this response is dependent on soil texture are still unknown. This study aimed to adjust boron fertilization for cotton as a function of the production environment and B source used. Two field experiments were conducted in the 2020/2021 season in Chapadão do Sul, MS (clayey soil—adequate B content) and Dracena, SP (sandy soil—low B content), Brazil. Treatments consisted of B sources (ulexite [low solubility], borax pentahydrate [BP] [intermediate solubility], and boric acid [BA] [high solubility]), and B rates (0, 1, 2, 4, and 6 kg ha−1) applied to the soil at 25 days after plant emergence. In sandy soil with low B content, application of 2 (high and medium solubility sources) and 4 kg B ha−1 (low solubility source) improved fiber yield between 10% (210 kg ha−1 fiber) and 28% (555 kg ha−1), respectively, as well as micronaire index, strength, elongation, uniformity, and short fibers. Application of B greater than 4 kg ha−1 via soluble sources reduced (between 9% (175 kg ha−1)—BP and 14% (257 kg ha−1)—BA) fiber yield only in sandy soil. When B content in the soil is adequate, B fertilization did not improve yield, but increased fiber strength (4%—1.1 g tex−1) and reduced the short fiber index (16%) by applying 1 kg B ha−1, regardless of the source used. The highest fiber yields were obtained with leaf B contents between 12 and 17 mg kg−1 (sandy soil) and 25 and 27 mg kg−1 (clayey soil). We recommend applying 2 kg B ha−1 (solubility sources) and 4 kg B ha−1 (low solubility source) in sandy soils with low B content to improve yield and fiber quality, and 1 kg B ha−1 in clayey soil with adequate B content to improve fiber quality and replace B amounts removed through harvesting. Core Ideas Boron fertilization in sandy soils increased fiber yield by 210–555 kg ha−1. There are no effects of B fertilization in clayey soils on fiber yield, but there are improvements in fiber quality. Rates greater than 4 kg ha−1 of B via soluble sources reduce fiber yield in sandy soils. Cotton grown in clayey soil is more resistant to B toxicity.

Nanocellulose-borax-polyvinyl alcohol (PVA) hybrid foams were prepared using a facile approach in an aqueous medium followed by a freeze-casting technique. Nanocellulose was well-dispersed in the PVA-borax (PB) matrix and acted as a cross-linking agent and nanofiller to bridge the 3D network, leading to enhanced mechanical and thermal performance. The effects of particle size, aspect ratio, surface charge and crystallinity on the microstructure and performance were investigated. With the increasing size and aspect ratio, cellulose nanofiber-PB foam with a density of ~0.110 g/cm 3 exhibited the most pronounced honeycomb-like structure with a porosity of 92.2%, the smallest cell diameter (~0.93 μm) and the highest mechanical strength (bearing more than 7560 times its own weight). Chemical cross-linking of nanocellulose-PVA foams with borax led to uniform porous structure, small pores and high mechanical strength. Possible lyophilization-induced assembly mechanisms, relationships between microstructure and mechanical properties, and complexation reactions between building blocks are proposed.