Addition Of Borax Research Articles

Preparation and microstructure evolution of novel ultra-low thermal conductivity calcium silicate-based ceramic foams

In this study, municipal solid waste incineration fly ash (MSWI FA) was used as a new raw material for the ceramics industry and a novel ultra-low thermal conductivity calcium silicate-based foams (CSFs) was prepared by the direct foaming method. The effects of the addition of foam and borax on the sintering behavior and microstructural evolution of the CSFs were investigated. With the optimal amount of foam, the CSFs had an apparent porosity of 63.43%–67.49%, bulk density of 0.75–0.84 g/cm3, compressive strength of 1.83–3.21 MPa, and room-temperature thermal conductivity of 0.213–0.235 W/(m·K). Notably, the whisker morphology, pore structure, and sintering behavior of the samples can be controlled by changing the amount of borax. The prepared ceramic foams can be applied in the fields of thermal insulation, filtration, and catalyst carriers.

Thermo-mechanical behaviour of fly ash-ladle furnace slag blended geopolymer with incorporation of decahydrate borax

This paper elucidates the effect of adding decahydrate borax (1 and 2 wt%) on thermo-mechanical properties of fly ash-ladle furnace slag (FS) geopolymer at 29 °C – 1000 °C. Adding borax improved the compressive strength of unheated (40.5 MPa) and heat-treated (36.9 – 43.1 MPa) FS geopolymers by 8.4% and 21.2%, respectively. The higher crystallinity, incompact microstructure, and the presence of B-bonds and B-crystals contributed to the high-temperature resistance of FS-B geopolymer. The reduced sintering temperature by 75 °C due to addition of borax compared to FS geopolymer improved the thermal stability and structural integrity during high-temperature applications.

Properties of Microplasma Coating on AZ91 Magnesium Alloy Prepared from Electrolyte with and without the Borax Addition.

Magnesium alloys, due to their unique properties, low density and high strength properties, are becoming more frequently used in industrial applications. However, a limitation of their use may be the need to ensure high abrasive wear resistance and corrosion resistance. Therefore, magnesium alloys are often protected by applying protective coatings. The paper presents the influence of the modification of the electrolyte composition, with or without the addition of borax, on the morphology (observed by SEM method) and phase composition (analyzed by EDS and XRD) of the formed layers on the AZ91 magnesium alloy, and their abrasive wear (determined with Ball-on-Disc method) and corrosion resistance (evaluated using the immersion method and by electrochemical tests), especially in chloride solutions. It has been clearly demonstrated that the modification of the electrolyte composition significantly impacts the final properties of the protective coatings on the AZ91 alloy formed by the plasma electrolytic oxidation (PEO) process. On the basis of the results, it was found that the new type of PEO coatings with the borax addition, compared to base PEO coatings, showed significantly higher abrasion resistance and an order of magnitude lower corrosion rate.

Developing Novel Fabrication and Optimisation Strategies on Aggregation-Induced Emission Nanoprobe/Polyvinyl Alcohol Hydrogels for Bio-Applications.

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0–5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2. In contrast to traditional methods, which are expensive and time-consuming and involve polymerization and post-functionalization to develop FL hyperbranched molecules, our proposed method offers a one-step method to prepare an AIE-HB nanoprobe with excellent FL characteristics. We employed the nanoprobe to fabricate fluorescent injectable bioadhesive gel and a hydrogel microchip based on polyvinyl alcohol (PVA). The addition of borax (50 mM) to the PVA + AIE nanoprobe results in the development of an injectable bioadhesive fluorescent gel with the ability to control AIEgen release for 300 min. When borax concentration increases two times (100 mM), the adhesion stress is more than two times bigger (7.1 mN/mm2) compared to that of gel alone (3.4 mN/mm2). Excellent dimensional stability and cell viability of the fluorescent microchip, along with its enhanced mechanical properties, proposes its potential applications in mechanobiology and understanding the impact of microstructure in cell studies.

Heat Transfer in Cassava Starch Biopolymers: Effect of the Addition of Borax.

In recent years, polymer engineering, at the molecular level, has proven to be an effective strategy to modulate thermal conductivity. Polymers have great applicability in the food packaging industry, in which transparency, lightness, flexibility, and biodegradability are highly desirable characteristics. In this work, a possible manner to adjust the thermal conductivity in cassava starch biopolymer films is presented. Our approach is based on modifying the starch molecular structure through the addition of borax, which has been previously used as an intermolecular bond reinforcer. We found that the thermal conductivity increases linearly with borax content. This effect is related to the crosslinking effect that allows the principal biopolymer chains to be brought closer together, generating an improved interconnected network favoring heat transfer. The highest value of the thermal conductivity is reached at a volume fraction of 1.40% of borax added. Our analyses indicate that the heat transport improves as borax concentration increases, while for borax volume fractions above 1.40%, heat carriers scattering phenomena induce a decrement in thermal conductivity. Additionally, to obtain a deeper understanding of our results, structural, optical, and mechanical characterizations were also performed.

Effects of diluted Concord grape juice laced with sodium chloride and selected boron-containing compounds on attraction, consumption, crop muscle contractions, and mortality of adult Drosophila suzukii Matsumura (Diptera: Drosophilidae).

In recent years, there has been interest in low-cost, reduced-risk materials that could be used for attract-and-kill of the invasive pest, spotted-wing Drosophila, Drosophila suzukii. This pest causes heavy economic damage to soft-skinned fruits in many countries. In this study, we evaluated physiological and behavioral effects of adding either borax, boric acid, or sodium chloride to diluted Concord grape juice (DGJ), a material that is attractive to adult D. suzukii. Results showed that the addition of borax, sodium chloride and boric acid did not significantly affect the response of adult D. suzukii, relative to DGJ alone. Increases in concentrations (to 5% and 10%) of borax, sodium chloride and boric acid were correlated with decreased ingestion of materials. Mortality of males and females was almost 100% with lower concentrations (1% and 5%) of borax and boric acid within 72 h. The higher concentrations of sodium chloride (5% and 10%) resulted in 100% mortality of both sexes within 72 h. There was no significant effect of chemicals on the number of crop contractions of flies when fed for 4h. This study suggests that some substances such as boric acid and borax may act as toxicants without influencing the behavioral response of D. suzukii. © 2021 Society of Chemical Industry.

The effect of borax addition to aluminum alloy produced by powder metallurgy on mechanical and thermophysical properties

PurposeLightweight, durable and economical materials production has gained considerable importance according to the needs of developing technology. The purpose of this paper is to develop an new aluminum alloy by powder metalurgy.Design/methodology/approachPowder metallurgy, which provides controllably on desired end product, method was applied. Aluminum alloy was created with Al, Zn, Mg, Cu powders and 1.5% Na2[B4O5(OH)4].8H2O added. It was pressed under high pressure and sintered at 600 °C under N2 gas atmosphere. Density, hardness behaviors and thermal properties were determined. Surfaces and crystal structures of samples were characterized.FindingsThe addition of borax made easier grains coming to together, acting as binders and the AlB2 crystal phase was formed. It was also observed that MgZn2, Al2CuMg phases were formed. In this way, the pores between the particles of the material were reduced from 35% to 5% total porosity and the hardness of the material was increased 29 N/mm2 to 45 N/mm2 (Brinell Hardness, HB). The surface properties improved and the hydrophobicity of the surface (from 63° to 102° contact angle with borax) increased. Thus, the heat transfer among atoms get easier and the borax addition decreased specific heat capacity and enthalpy of aluminum–borax samples. This situation was also simulated with the heat transfer module of COMSOL. As result, the energy required reduced. In the other word, sintering process occurred at low temperature and more efficient.Originality/valueNew aluminum alloy has been created from different amounts of Zn, Mg, Cu elemental powders. In addition to literature, relationship of borax and aluminum and other alloying elements on the mechanical, thermophysical and surface properties of new obtained aluminum alloy has been investigated.

Coatings Based on Phosphate Cements for Fire Protection of Steel Structures.

Fire events in buildings can cause losses to human life and important material damage, therefore a great deal of attention is paid nowadays to fire prevention. Buildings based on steel structures are especially affected in the event of a fire, due to the important loss of load-bearing capability when steel is heated at temperatures higher than 500 °C. Therefore, one possible method to mitigate the deleterious effect of fire is to protect steel structures from direct heating by applying protective coatings. In this paper, the ability of magnesium phosphate cement (MPC), based on dead burned magnesite and calcium magnesium phosphate cement (CMPC) coatings, to protect a steel substrate was assessed. CMPCs were obtained by mixing partially calcined dolomite with a KH2PO4 (MKP) solution, and in some cases, with a setting retarder (borax). The main mineralogical compounds assessed by X-ray diffraction and electronic microscopy (SEM-EDS) in CMPC are MgO, CaCO3, and K-struvite (KMgPO4·6H2O). The coatings based on MPC and CMPC, applied to steel plates, were tested in direct contact with a flame; the coatings of MPC and CMPC without the borax addition prevented the temperature increase of a metal substrate above 500 °C. No exfoliation of coatings (MPC and CMPC without borax addition) was noticed during the entire period of the test (45 min).

The Effects of Borax (NA2B4O710H2O) on Histopathology of Wistar Rats’ Cerebrum (Rattus norvegicus)

The present study aimed to determine the effects of borax (Na2B4O7.10H2O) addition on the changes of histological cerebrum imaging in the brains of white mice (Rattus norvegicus). The current research was an experimental study with randomization of 24 white mice that were divided into four treatment groups with five replications. Borax was dissolved for each treatment with a dose of 19 mg/mouse/day, 26 mg/mouse/day, and 37 mg/mouse/day, and it was administered orally for 14 days. Then, it was analyzed statistically using the Kruskal-Wallis test. The statistical analysis results suggested that there were significantly different results in each treatment group. The control treatment with an administration dose of 26 mg/rat/day had a significantly different result in the worst cloudy swelling degeneration of cerebrum in histopathology imaging on Wistar rats (Rattus norvegicus). Using the Mann-Whitney test, it was found that the dose of borax at 37 mg/rat/day led to significant difference, compared to the other treatment groups, which means that 37 mg/rat/day of borax caused the worst pyramidal cell necrosis in histopathology imaging of the cerebrum on white mice. Borax exposure on Wistar rats (Rattus norvegicus) can cause cloudy swelling at a dose of 26mg/head/day, and pyramidal cell necrosis at a dose of 37 mg/head/day.

The addition of magnesium sulfate and borax to urea reduced soil NH3 emissions but increased N2O emissions from soil with grass

Nitrogen (N) use efficiency can be increased by the addition of substances to urea. Magnesium sulfate (MgSO4) and boron were considered as plant nutrients, while zeolite was used as soil conditioner. The addition of these substances may affect soil NH3 and N2O emissions, by increasing N use efficiency. We conducted an 30 days incubation experiment with ryegrass using fertilizer treatments (12 g N m−2) as follows: urea (U); urea + MgSO4 (UM); urea + MgSO4 + borax (UMB); zeolite + urea + MgSO4 (Z-UM); and zeolite + urea + MgSO4 + borax (Z-UMB). We measured NH3 and N2O emissions and the aboveground N uptake of ryegrass. Cumulative NH3 emissions of UM, UMB, Z-UM and Z-UMB were 10%, 53%, 21% and 58% lower than U, respectively, while their N2O emissions were 32%, 133%, 43% and 72% higher than U, respectively. Aboveground N uptake of UM, UMB, Z-UM and Z-UMB were 9%, 6%, 12% and 13% higher than U, respectively. Overall, we suggest that the addition of MgSO4 and borax were effective in reducing NH3 emissions and potentially increase plant N uptake. However, the risk of higher denitrification and N2O emissions also needs to be considered. This study reveals the considerable effect of MgSO4 and borax in soil N cycles. Future research should evaluate how the application of urea + MgSO4 + borax effects gaseous emissions and crop yield of dicotyledons and in drier soil conditions.

Rheological criteria for distinguishing self-healing and non-self-healing hydrogels

Owing to the structural resemblance of synthetic hydrogels to biological tissues, numerous self-healing wet materials have recently emerged, based on either chemical or physical motifs. With a plethora of novel synthetic hydrogels, a reliable characterisation strategy to assess self-healing is necessary. Herein, we therefore propose rheological criteria to distinguish self-healing hydrogels by comparing two types of poly (vinyl alcohol) hydrogels prepared via freezing/thawing (FX) or borax addition (BX). Non-self-healing FX and self-healing BX hydrogels exhibit incompatible features for three rheological characteristics: 1) Bingham behaviour without a lower Newtonian flow region (LNFR) (FX) versus pseudoplastic behaviour with a LNFR (BX), 2) infinite chain flow relaxation time (τf) versus finite τf on a reasonable time scale, and 3) drastic gel-sol transition with heating versus negligible transition. The plotting of modulus master curves confirms the terminal flow behaviour of the self-healing BX hydrogels, in contrast to the rubbery nature of the FX gels. The flowability of the self-healing hydrogels is ascribed to the pseudo-state of the gel network, due to the dynamic nature of the borate-diol bonds. Thus, the rheological criteria provide a sound theoretical background for self-healing material characterisations.

Historical grisailles characterisation: A literature review

• Literature from 1984 to 2020 regarding grisaille is reviewed. • The spatio-temporal study reflects changes in grisailles composition. • The iron oxide is the main colouring agent identified throughout the centuries. • In Germany, Italy and Czech Republic the copper oxide is in higher proportion. • The main substrate glasses identified are sodium-rich and potassium-rich glasses. This work presents the first review on the characterisation of grisaille stained-glass paint, in order to follow the evolution of the production materials and methods throughout time and provenance. From the literature review, 38 scientific studies regarding the grisaille paint were found, dated between 1984 and 2020. In these works, various samples from the 13 th to the 20 th centuries belonging to 11 different European countries were characterised. In general, iron oxide was the main colouring agent identified throughout the centuries and countries, except in the Central and South-Central European countries where copper oxide was preferably used. Different metal oxides, such as cobalt, chromium and manganese were also identified in modern samples (19 th and 20 th centuries), used together with iron oxides. The base glasses generally presented a lower ratio PbO:SiO 2 (~0.5 to 1) than the expected from the historical recipes, and the addition of borax is suggested for grisailles from the 17 th century onwards. The proportion between the base glass and colouring agents showed ratios between 1 and 1.5, related to well-balanced grisailles. The present overview, critical analysis and comparison of published studies regarding this glass-based paint allow to draw a spatio-temporal map of the grisaille composition evolution, which reflects the changes in composition regarding the country of provenance and century.

The Study of Formaldehyde and Borax Content on Salted Fish from Several Markets in Tembilahan Indragiri Hilir, Riau

Fisheries and marine sector is one of the potential sectors in Indragiri Hilir district, Riau. Local fishermen make efforts to preserve the catch by salting it. Although salt can extend product shelf life, there are still many salted fish producers that add formaldehyde and borax to reduce production costs. The addition of formaldehyde and borax is carried out with the aim of extending product shelf life so that producers do not lose. The aim of this study was to determine the presence of formalin and borax content in salted fish products in several markets in Tembilahan. The sampling method in this study was simple random sampling by taking three different samples of salted fish, namely salted belukang, salted kembung, and salted gulama in three different markets in Tembilahan. Samples were tested for formalin and borax using test kit. The results of the qualitative formalin content test showed that from 9 samples of salted fish from several Tembilahan markets, there were 5 positives samples containing formaldehyde. The five samples were salted salted fish belukang, salted fish kembung, salted fish gulama from central market, and salted fish gulama and salted fish kembung from Parit 11 market. In the other hand, the salted fish samples were also tested qualitatively for borax content test. The qualitative test results of borax on 9 samples from several markets in Tembilahan showed no color change on the turmeric paper after immersion in the sample solution. This indicates that all salted fish samples is negative for borax content.

Study of Tensile Strength Test of Oxi-Asetyline Welding with the Addition of Borax to St 37 Steel

The use of welding in industry today is very broad, including shipping, machinery, construction and others. The aim of this research was to study the welding results of two types of metal with different melting points, namely low carbon steel ST37 with brass filler and borax added during the welding process using OAW (Oxygent Acetyline Welding) welding. The specimen size is 170 mm long, 50 mm wide and 8 mm thick. As for the test method with the addition of borax, then look at the results of the number of porosity, weld defects and differences in tensile strength in each specimen by conducting penetrant liquid testing and tensile testing with ASTM E-8 standards. The results of the penetrant liquid test showed that welding ST 37 steel using borax as an additional material produced welding with the smallest porosity and even no defects at all compared to specimens without using borax. The results of the tensile test show that the addition of borax has a tensile strength value of 2000 kgf / mm². This value is greater than without the addition of borax.

Use of Preservatives in Vegetable Protein-Based Food Attractants for Monitoring Anastrepha fraterculus (Diptera: Tephritidae) in Peach Orchards.

Studies have demonstrated that the addition of preservatives mixed with food attractants have provided a more expressive attractiveness for fruit fly adults. The objective of the study was to evaluate the capture of Anastrepha fraterculus (Wiedemann, 1830) adults when the addition of borax and/or benzalkonium chloride preservative in BioAnastrephaTM and Isca Samaritá TradicionalTM food attractants compared to CeraTrapTM (control, no preservatives added) in peach orchards. As well as, verifying the effect over non-target insects. BioAnastrephaTM, Isca Samaritá TradicionalTM and CeraTrapTM attractants enabled the capture of A. fraterculus adults when used by themselves in McPhail traps. However, by adding borax and benzalkonium chloride, BioAnastrephaTM and Isca Samaritá TradicionalTM food attractants significantly increased the number of adults captured. Additionally, the number of A. fraterculus adults captured by BioAnastrephaTM attractant + borax was similar to CeraTrapTM attractant over time. Regarding non-target insects, the highest percentages of subjects captured belong to the Coleoptera (4.4 to 11%) and Diptera orders (24.1 to 34.6%) (Drosophilidae family). Nevertheless, insects from the Hymenoptera order [(Formicidae (0.14 to 0.96%), Vespidae (0.02 to 0.3%), and Apidae (0.04 to 0.9%)] families. Neuroptera (0.02 to 0.98%) and Lepidoptera (0.09 to 0.7%) were also captured, although those amounted to less than 1% of the A. fraterculus total. Adding borax and benzalkonium chloride to BioAnastrephaTM and Isca Samaritá TradicionalTM food attractants potentialize the effect of A. fraterculus capture in monitoring traps. Also, adding preservatives made attractants more durable, consequently, the need to replace attractants was not as frequent.

Effect of early-hydration behavior on rheological properties of borax-admixed magnesium phosphate cement

Magnesium phosphate cement (MPC), as a new-fashioned cementitious material with doubly consensus superiorities of rapid-setting and ultra-high early strength, has a significant utilization potentiality in multi-extremely complicated engineering fields. Borax had been employed for prolonging the setting time of MPC as an unexceptionable retarder, which has been verified and approved practically. Nevertheless, the effect of early-hydration behavior on rheological properties (RPs) in borax-admixed MPC remains obscure. Consequently, we adopted rheometer to investigate the RPs of MPC with different borax contents, and then discussed the relationship between yield stress and plastic viscosity affected by hydration process. In addition, a series of microscopic methods were utilized for further exploring the influence of hydration process and products on the RPs of borax-admixed MPC. Results indicated that: 1) The yield stress and plastic viscosity of MPC dramatically decreased with the borax content, and the consequences induced by final curve-fitting are basically in accordance with Bingham model. 2) The Zeta potential exhibited that borax content had no significant effect on the continuous stability of the colloidal dispersion. Moreover, results of electrochemical impedance expressed that increasing the amount of borax enhanced the concentration of ions in MPC, which further induced reduced electrical impedance. 3) Low-field nuclear magnetic resonance and analysis of thermo-gravimetry and derivative thermo-gravimetry conveyed that the addition of borax had a distinct delayed coagulation on MPC, which was mainly attributed to the combination of B(OH4)- and Mg2+ for producing complexes during hydration and then constituted the retarder layer to delay the formation of struvite compared with normal hydration. 4) XRD results indicated that the rupture of retarder layer was the direct inducement of RPs enhancement after hydration reaction had been basically completed. All results verify the interaction between retarded hydration reaction of borax and enhanced RPs, which provide an important reference for the future repairing research of MPC.

Effect of mixture proportioning on the strength and mineralogy of magnesium phosphate cements

Magnesium potassium phosphate cement (MKPC) has properties advantageous over ordinary portland cement such as quick setting and rapid strength gain. Although the effect of mixture proportioning on MKPC pastes has been studied, there are conflicting reports on how calcination of magnesia, parameters like magnesium-to-phosphate ratio (M/P) and water-to-binder ratio (W/B), added materials like borax and fly ash, or the addition of sand influence mineralogy and properties like setting and strength. These factors are evaluated over a practical range of values for each using X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy on paste samples. Strength development is evaluated using both pastes and mortars. Calcination of magnesia forms some forsterite with impurity SiO2 which may be linked to the reduction of reactivity. Increasing W/B increases setting time more significantly at lower M/P. Increasing M/P increases early strength but not so much ultimate strength. The main final phases in the pastes are K-struvite and unreacted MgO. Addition of borax or low-lime fly ash does not alter the mineralogy of hydrated pastes. Varying M/P simply changes the relative amounts of these solid phases. Unlike in Portland systems, adding up to ~60 vol% sand to pastes does not decrease strength considerably.

Immobilization of Heavy Metals in Boroaluminosilicate Geopolymers.

Boroaluminosilicate geopolymers were used for the immobilization of heavy metals. Then, their mechanical properties, phase composition, structure, and microstructure were investigated. The addition of borax and boric acid did not induce the formation of any crystalline phases. Boron was incorporated into the geopolymeric network and caused the formation of N–B–A–S–H (hydrated sodium boroaluminosilicate) gel. In the range of a B/Al molar ratio of 0.015–0.075, the compressive strength slightly increased (from 16.1 to 18.7 MPa), while at a ratio of 0.150, the compressive strength decreased (to 12 MPa). Heavy metals (lead and nickel) were added as nitrate salts. The loss of the strength of the geopolymers induced by heavy metals was limited by the presence of boron. However, it caused an increase in heavy metal leaching. Despite this, heavy metals were almost entirely immobilized (with immobilization rates of >99.8% in the case of lead and >99.99% in the case of nickel). The lower immobilization rate of lead was due to the formation of macroscopic crystalline inclusions of PbO·xH2O, which was vulnerable to leaching.

Borax induces osteogenesis by stimulating NaBC1 transporter via activation of BMP pathway

The intrinsic properties of mesenchymal stem cells (MSCs) make them ideal candidates for tissue engineering applications. Efforts have been made to control MSC behavior by using material systems to engineer synthetic extracellular matrices and/or include soluble factors in the media. This work proposes a simple approach based on ion transporter stimulation to determine stem cell fate that avoids the use of growth factors. Addition of borax alone, transported by the NaBC1-transporter, enhanced MSC adhesion and contractility, promoted osteogenesis and inhibited adipogenesis. Stimulated-NaBC1 promoted osteogenesis via the BMP canonical pathway (comprising Smad1/YAP nucleus translocation and osteopontin expression) through a mechanism that involves simultaneous NaBC1/BMPR1A and NaBC1/α5β1/αvβ3 co-localization. We describe an original function for NaBC1 transporter, besides controlling borate homeostasis, capable of stimulating growth factor receptors and fibronectin-binding integrins. Our results open up new biomaterial engineering approaches for biomedical applications by a cost-effective strategy that avoids the use of soluble growth factors.

Microstructural and corrosion behavior of MAO coated 5052 aluminum alloy

In this paper, the morphology, phase composition and corrosion behavior of micro-arc oxidized 5052 aluminum alloy were analyzed. A uniform micro arc oxidation (MAO) coating was performed on 5052 aluminium alloy in different electrolytes (with and without borax additives) for 30 min. The MAO coating thickness was measured around 17–24 µm and nanocrystalline γ-Al2O3 were identified in the MAO coating using XRD analysis. The coating thickness was measured using the eddy current technique and morphology of the coating was analyzed using SEM. The coating formed in the electrolyte with borax showed reduced porosity compared to the sample coated without borax. The corrosion behavior is analyzed by Potentiodynamic polarization. The MAO coated sample offers higher corrosion resistance when compared to the uncoated specimen due to higher corrosion potential.