Ethylenediaminetetraacetic Acid Treatment Research Articles

Effects of ethylenediaminetetraacetic acid chelation for calcific band keratopathy on corneal topography assessed by fourier harmonic analysis.

Chemical chelation with ethylenediaminetetraacetic acid (EDTA) is an established treatment for calcific band keratopathy (CBK), whereas removal of calcium deposits from the subepithelial layer of the cornea may cause corneal irregularity. Using Fourier harmonic analysis, we analyzed the corneal topography in eyes with CBK treated by EDTA chelation. Retrospective, single-center study. This study included 42 eyes of 26 patients who underwent chemical chelation using EDTA for CBK at the Kyorin University Hospital. Clinical data included age, sex, refraction, visual acuity, operation records, and corneal topography. Corneal topography was evaluated by a TMS-5 Corneal Topographer, and 3.0- and 6.0-mm-diameter Fourier series harmonic analyses were performed. Refraction, visual acuity, and parameters of corneal topography were compared before surgery and at 1 and 4 weeks postoperatively. Visual acuity and refraction (spherical equivalent and astigmatism) did not significantly change at 4 weeks postoperatively. Fourier harmonic analysis revealed that there were no time serial changes in the spherical component and regular astigmatism in both 3.0- and 6.0-mm analyses. Asymmetry astigmatism, and high-order irregularity significantly increased at 1 week postoperatively but decreased at 4 weeks postoperatively, with no statistical differences compared with preoperative data. The effects of EDTA treatment on the corneal shape and refraction are minimal, which is beneficial for maintaining visual function in patients with CBK.

Purification and characterization of limonin D-ring lactone hydrolase from sweet orange (Citrus sinensis (L.) Osbeck) seeds.

Citrus products often suffer from delayed bitterness, which is generated from the conversion of non-bitter precursors (limonoate A-ring lactone, LARL) to limonin under the catalysis of limonin D-ring lactone hydrolase (LDLH). In this study, LDLH was isolated and purified from sweet orange seeds, and a rapid and accurate high-performance liquid chromatography method to quantify LARL was developed and applied to analyze the activity and enzymatic properties of purified LDLH. Purified LDLH (25.22 U mg-1) showed bands of 245 kDa and 17.5 kDa molecular weights in native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE analysis respectively. After a 24 h incubation under strongly acidic (pH 3) or strongly alkaline (pH 9) conditions, LDLH still retained approximately 100% activity. Moreover, LDLH activity was not impaired by thermal treatment at 50 °C for 120 min. Enzyme inhibition assays showed that LDLH was inactivated only after ethylenediaminetetraacetic acid treatment, and other enzyme inhibitors showed no significant effect on its activity. In addition, the LDLH activity of calcium ion (Ca2+) intervention was 108% of that in the blank group, and that of zinc ion (Zn2+) intervention was 71%. LDLH purified in this study was a multimer containing 17.5 kDa monomer with a wide pH tolerance range (pH 3-9) and excellent thermal stability. Moreover, LDLH might be a metallopeptidase, and its activity was stimulated by Ca2+ and significantly inhibited by Zn2+. These findings improve our understanding of LDLH and provide some important implications for reducing the bitterness in citrus products in the future. © 2024 Society of Chemical Industry.

Surface modification of halide perovskite using EDTA-complexed SnO2 as electron transport layer in high performance solar cells.

The long-term performance of metal halide perovskite solar cells (PSCs) can be significantly improved by tuning the surface characteristics of the perovskite layers. Herein, low-temperature-processed ethylenediaminetetraacetic acid (EDTA)-complexed SnO2 (E-SnO2) is successfully employed as an electron transport layer (ETL) in PSCs, enhancing the efficiency and stability of the devices. The effects of EDTA treatment on SnO2 are investigated for different concentrations: comparing the solar cells' response with 15%-2.5% SnO2 and E-SnO2 based ETLs, and it was found that 7.5% E-SnO2 provided the best results. The improved surface properties of the perovskite layer on E-SnO2 are attributed to the presence of small amount of PbI2 which contributes to passivate the defects at the grain boundaries and films' surface. However, for the excess PbI2 based devices, photocurrent dropped, which could be attributed to the generation of shallow traps due to excess PbI2. The better alignment between the Fermi level of E-SnO2 and the conduction band of perovskite is another favorable aspect that enables increased open-circuit potential (VOC), from 0.82 V to 1.015 V, yielding a stabilized power conversion efficiency of 15.51%. This complex ETL strategy presented here demonstrates the enormous potential of E-SnO2 as selective contact to enhance the perovskite layer properties and thereby allow stable and high-efficiency PSCs.

Sealing ability of various endodontic sealers with or without ethylenediaminetetraacetic acid (EDTA) treatment on bovine root canal

This study investigated the wettability and consistency of various endodontic sealers, both inorganic and organic, and evaluated their sealing ability of root canals using the single-cone obturation technique, with and without ethylenediaminetetraacetic acid (EDTA) treatment. Bovine root canals were endodontically prepared and filled in preparation for the dye penetration test with toluidine blue solution. All sealers exhibited contact angles similar to or lower than dentin and displayed superior consistency. Among the sealers, organic sealers used without EDTA treatment showed reduced dye penetration compared to inorganic sealers. However, some inorganic and organic sealers showed dye penetration in the sealer and dentin of root canals subjected to EDTA treatment. In conclusion, the single-cone obturation technique, combined with these endodontic sealers, achieved close contact with root canal dentin due to their wettability and consistency. However, the sealing ability of certain sealers was influenced by EDTA treatment.

Effective collection of protein-enriched cells from green tea residue: An innovative process for leaf protein production

Green tea residue (GTR) contains a high protein content. However, the protein in GTR can't be effectively extracted using traditional methods. Thus, a novel method using ethylenediamine tetraacetic acid (EDTA), ammonium oxalate, or Celluclast® 1.5 L were used to disperse leaf tissues and to collect mesophyll cells to enrich the protein. Compared with EDTA or ammonium oxalate treatment, Celluclast® 1.5 L treatment achieved the highest amounts of mesophyll cells, about 2.7 × 106 g−1 of GTR. The number of collected mesophyll cells was positively and linearly correlated with the extraction rate of glucose and xylose, indicating that cellulose and hemicellulose were key components influencing cell collection. Celluclast® 1.5 L treatment enriched the protein content by 1.65 times in collected mesophyll cells to 50% protein content with a protein recovery of 88%, providing a novel scheme to obtain high-quality leaf protein for the food industry.

Reevaluating the accuracy and specificity of EDTA-based polyphosphate quantification method

Feng et al. (2020) developed a simple, nondestructive, and cost-effective method to quantify polyphosphate (poly-P) in poly-P-accumulating organism (PAO)-enriched sludge samples through 30-h anaerobic exposure to 1 % (w/v) ethylenediaminetetraacetic acid (EDTA). This study optimized the N/P ratio (∼2) of the PAO culture medium in order to provide excess P for poly-P formation in PAO cells. Subsequently, the fluorescence microscopic observation of stained cells confirmed that Corynebacterium glutamicum was a PAO species capable of heterotrophic nitrification. Finally, this study reevaluated the accuracy and specificity of the EDTA-based quantification method, using two confirmed PAO biomass, three confirmed non-PAO biomass, and two sludge samples. The 1 % (w/v) EDTA treatment appears destructive to non-PAO cells, causes the release of other P forms, and is not effective for all PAO species. Under the conditions, the actual P release amount should be calculated by subtracting approximately 8 mg P g−1 total suspended solids from the determination. The amounts of P released from sludge samples was determined not only by the PAO fractions described by Feng et al. but also by PAO community structure and sludge P content.

Fibroblast Viability Through Mechanical and Chemical Root Surface Modifications in Periodontal Healing: An In Vitro Comparative Study.

The wound-healing process incorporates a spectrum of periodontal therapeutic interventions that strive to restore the health and function of the periodontium. Fibroblasts play pivotal roles in tissue repair and regeneration. Extensive research has been focused on mechanical and chemical root surface modifications to enhance fibroblast adhesion, which is crucial for successful wound healing. This study aimed to assess the combined efficacy of mechanical and chemical root surface modifications in promoting fibroblast viability to root surfaces affected by periodontitis in comparison to chemical modifications alone. Root samples were collected from healthy individuals and those with advanced periodontitis. The specimens were prepared, and the experimental groups were categorized based on the type of surface modification with mechanical and/or chemical materials, including hyaluronic acid (HA), ethylenediaminetetraacetic acid(EDTA), enamel matrix derivatives (EMD), and EDTA/EMD. Fibroblasts were seeded onto previously treated root samples. Cell adhesion was assessed using a viability assay. Fibroblast viability was significantly higher on root surfaces treated with chemical agents than on those treated with mechanical and chemical modifications. Long-duration EDTA and short-duration EMD treatments were significantly effective in enhancing cell viability. EDTA/EMD surface treatments resulted in significantly higher cell viability in all groups compared to the periodontitis root surfaces. EDTA, EMD, and their combined application can potentially ameliorate periodontitis-induced surface structural impairments. Mechanical surface debridement can significantly affect the effectiveness of EDTA and EMD root conditioning agents.

Pattern of Lead Accumulation in Two Vegetable Plants Due to EDTA Treatment

Phytoextraction and phytostabilization are the most consistent patterns or mechanisms of action of phytoremediation. One of the elements influencing the mechanism of action of heavy metal absorption by plant species is Ethylene Diamine Tetraacetic Acid (EDTA). Therefore, this study aimed to determine the pattern of phytoremediation in water spinach and spinach due to the addition of EDTA in the soil. The treatments tested by factor 1 were water spinach (T1) and spinach (T2), and factor 2 was the concentration of EDTA consisting of 3 levels, 0, 3, and 6 g/polybag. Each treatment was repeated three times on five sample plants. Furthermore, growth evaluation was carried out in the first six days after planting and conducted every 3 days. It was carried out on variables such as changes in plant height, leaves area, total root length, Pb content in the soil, fresh and dry weight of shoots and roots, shoot, seeds, and Translocation Factor (TF). The results showed that water spinach and spinach had different mechanisms of action due to the application of EDTA in Pb-contaminated media. Furthermore, water spinach and spinach have a mechanism of phytoextraction and phytostabilization, respectively. Therefore, spinach is safer than water spinach when grown in Pb-polluted land.

Enhancing the Photovoltaic Performance of Cd(1−x)ZnxS Thin Films Using Seed Assistance and EDTA Treatment

This research article provides a comprehensive investigation into the optoelectronic characteristics of three distinct types of cadmium sulfide (CdS) thin films, namely: (a) conventionally prepared CdS thin films using chemical bath deposition (CBD-CdS), (b) CdS thin films produced via chemical bath deposition with the inclusion of zinc (CBD-Cd(1−x)ZnxS, x = 0.3), and (c) CdS thin films synthesized using a seed-assisted approach, treated with ethylenediaminetetraacetic acid (EDTA), and incorporating zinc (ED/CBD + EDTA-Cd(1−x)ZnxS). The investigation reveals that the crystallite size of these thin films decreases upon the addition of EDTA to the reaction solution, leading to an increase in the inter-planar spacing and dislocation density. Furthermore, a blue shift in the transmittance edge of the ED/CBD + EDTA-Cd(1−x)ZnxS samples compared to CBD-CdS implies modifications in the band gaps of the deposited films. The incorporation of Zn2+ into the reaction solution results in an increased band gap value of up to 2.42 eV. This suggests that Cd(1−x)ZnxS thin films permit more efficient photon transmission compared to conventional CdS. Among the three types of films studied, ED/CBD + EDTA-Cd(1−x)ZnxS exhibits the highest optical band gap of 2.50 eV. This increase in the optical band gap is attributed to the smaller crystallite size and the splitting of the tail levels from the band structure. Additionally, the increment in the optical band gap leads to reduced light absorption at longer wavelengths, thereby enhancing the electrical properties. Notably, ED/CBD + EDTA-Cd(1−x)ZnxS thin films demonstrate improved photovoltaic performance in a photoelectrochemical (PEC) cell, characterized by enhanced open-circuit voltage (363 mV, VOC), short-circuit current (35.35 μA, ISC), and flat-band voltage (−692 mV, Vfb). These improvements are attributed to the better adhesion of CdS to the fluorine-doped tin oxide (FTO) substrate and improved inter-particle connectivity.

Effects of ethylenediaminetetraacetic acid on growth and survival of long-spined sea urchin Diadema antillarum larvae

Abstract Objective The presence of heavy metals in seawater is a major challenge for hatchery culture of sea urchin larvae due to their sensitivity to metal pollution. The impact of heavy metals in seawater for sensitive marine larviculture could be minimized via chelation of metals using chemical compounds such as ethylenediaminetetraacetic acid (EDTA). Methods In this study the effects of EDTA were tested for the long-spined sea urchin Diadema antillarum during larviculture at two concentrations (10 μM and 50 μM) and two exposure durations (6 and 24 days postfertilization). Growth and survival of larvae were evaluated as response variables. Result Significant differences in growth and survival of larvae were found among the treatments at different EDTA concentrations and exposure durations. The 10-μM EDTA treatment enhanced growth and survival of larvae relative to control for both exposure durations. The 50-μM EDTA treatment was unsuitable for long-spined sea urchin larviculture due to reductions in growth and survival. Conclusion The use of 10 μM EDTA during embryo incubation and larviculture is expected to improve long-spined sea urchin larval fitness, leading to improved hatchery production.

Effective citric acid and EDTA treatments in cadmium stress tolerance in pepper (Capsicum annuum L.) seedlings by regulating specific gene expression

Soil contamination with toxic environmental pollutants [such as cadmium (Cd)] is becoming a serious global problem due to rapid development of social economy. To improve the growth and yield of a plant, various chelating agents, such as ethylenediaminetetraacetic acid (EDTA) and citric acid (CA), can be applied to the soil; such application not only increases plant uptake of metals from the soil but also promotes plant absorption of micronutrient fertilizers from the medium. For this purpose, we have conducted a pot experiment using the exogenous application of CA (2.5 mM) and EDTA (2.5 mM) in pepper (Capsicum annuum L.) seedlings grown under the varying levels of Cd (0, 50 and 100 µM) in the soil. M]. Our results depicted that Cd addition to the soil significantly (P < 0.05) decreased plant growth and biomass, gas exchange attributes, and mineral uptake by C. annuum when compared to the plants grown without the addition of Cd. However, Cd toxicity boosted the production of reactive oxygen species (ROS) by increasing the content of malondialdehyde (MDA), which is the indication of oxidative stress in C. annuum, and was also manifested by hydrogen peroxide (H2O2) content and electrolyte leakage to the membrane-bound organelles. The results showed that the activities of various antioxidative enzymes, such as superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and their specific gene expression and also the content of non-enzymatic antioxidants, such as phenolic, flavonoid, ascorbic acid, and anthocyanin, initially increased with an increase in the Cd concentration in the soil. The results also revealed that the levels of soluble sugar, reducing sugar, and non-reducing sugar were decreased in plants grown under elevating Cd levels, but the accumulation of the metal in the roots and shoots of C. annuum, was found to be increased. The negative impacts of Cd injury were reduced by the application of EDTA and CA, which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes and their gene expression, and mineral uptake, as well as diminished the exudation of organic acids and oxidative stress indicators in C. annuum by decreasing Cd toxicity. Here, we conclude that the application of EDTA and CA under the exposure to Cd stress significantly improved plant growth and biomass, photosynthetic pigments, and gas exchange characteristics; regulated antioxidant defense system and essential nutrient uptake; and balanced organic acid exudation pattern in C. annuum.

Enhancing attachment of human gingival fibroblasts to periodontally compromised teeth: A comparative analysis of hyaluronic acid, EDTA, enamel matrix derivatives

BackgroundGingival recession is a characteristic indicator of periodontitis and one of the factors that contributes to increased tooth clinical crown length. Patients with root exposure frequently undergo periodontal surgical procedures in addition to adjunctive therapy to increase root coverage area and soft tissue stability. PurposeThis study aimed to evaluate fibroblast-root surface adhesion and determine whether periodontitis-damaged root surface microstructure can be restored using ethylenediaminetetraacetic acid (EDTA) and an enamel matrix derivative (EMD), individually or in combination. Material and methodsTeeth extracted from patients with periodontal disease were used to create 60 samples, with each group containing six specimens. The test groups were provided root planing or root condition-specific materials (hyaluronic acid [HA], 24% EDTA, EMD, or EDTA/EMD) for varying treatment time periods. In contrast, the control group did not undergo any surface modifications. The samples and fibroblast cells were incubated for 72 h. The number of living cells on the root surface in each group was calculated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (cell viability assessment). ResultsThe control, root planing, and EMD groups showed that the root surfaces treated with EDTA for 4 min had significantly better cell adhesion. Surface EDTA treatment for 2 min significantly promoted cell attachment compared to root planing treatment. The root surfaces modified with EDTA/EMD for 2 and 4 min showed significantly improved cellular migration and adhesion compared to the root surface treated with root planing. ConclusionEDTA and EDTA/EMD substantially affected the root surface, which was related to the length of the treatment process. This effect shifts the surface properties, alters fibroblast interactions with the root surface, and recruits more cells to cover a larger area.

Microplastic isolation method for wastewater and sludge samples by removal of excess organic and inorganic interferences

The isolation of microplastics from other organic and inorganic contents is a major hurdle to the effective quantification and characterization of microplastics in wastewater and biosolids samples. As a result, a well-established and standardized isolation method is vital for the analysis of microplastics. In this study, we evaluated biological hydrolysis, enzymatic hydrolysis, wet peroxidation and ethylenediaminetetraacetic acid treatment for microplastics isolation and demonstrated that the integration of these processes can effectively remove organic and inorganic contents to provide a clear microscope view for microplastics identification from wastewater and sludge samples. To the best of our knowledge, this study is the first to introduce biological hydrolysis and ethylenediaminetetraacetic acid treatment for the isolation of microplastics from environmental samples. The results reported could facilitate the establishment of a standardized procedure for microplastic isolation from wastewater and biosolid samples.

Comparing the performance of demineralization agents (HCl and EDTA) for stable isotope analysis of bone collagen with implications for quality control criteria and collagen yield

AbstractStable isotope analysis of ancient bone collagen is a powerful technique for studying diet, migration, and ecology in archeological contexts. These analyses are, however, limited by collagen preservation and prohibitively low collagen yields. Harsh chemical demineralization is required to isolate the collagen from the mineral component of the bone, which in turn reduces the yield of material available for analysis. Demineralization is typically performed using hydrochloric acid (HCl), which reduces collagen yield via acid hydrolysis of peptide bonds. An alternative to a strong acid (HCl) treatment is the neutral chelating agent ethylenediaminetetraacetic acid (EDTA). To our knowledge, it has never been empirically tested whether EDTA treatment reduces collagen loss relative to HCl in samples that are known to be poorly preserved (i.e., low yields and/or collagen extracts failing other collagen quality control [QC] criteria). We tested the effect of the demineralization agent on collagen yield, stable isotope, and elemental composition of poorly preserved ancient bone samples. Collagen yield was significantly higher in EDTA‐treated samples; however, this did not translate into a greater number of samples passing relevant quality control criteria. Stable isotope compositions (SIC) were also not significantly different between treatments. The atomic C:N ratio of samples treated with EDTA was significantly lower than equivalent samples treated with HCl, which is likely a product of increased deamidation of asparagine and glutamine residues when collagen is demineralized with HCl relative to EDTA. We conclude that although EDTA treatment may reduce collagen loss relative to HCl treatment, this does not necessarily increase the probability of producing reliable–stable isotope data from bone samples yielding low amounts of collagen. Based on our isotopic data, we suggest the following provisional collagen QC criteria for EDTA‐demineralized samples: collagen yield &gt; 2%, wt% C &gt; 4%, wt% N &gt; 2%, and atomic C:N ratio between 2.80 and 3.25.

Modification of UHPC Matrix and Fiber Surface for Improving the Mechanical Performance of Ultra-High-Performance Fiber-Reinforced Concrete

In this study, filler and silica fume were substituted by Liquid crystal display glass powder (LCDGP) and nanosilica, respectively, to improve the performance of ultra-high- performance fiber-reinforced concrete. In addition, the surface of steel fiber was modified with ethylenediaminetetraacetic acid (EDTA) solution to improve the interfacial friction between the fiber and Ultra-high-performanceconcrete (UHPC) matrix. Both LCDGP and nanosilica reacted with calcium hydroxide to form hydrates, and the fiber surface roughness increased owing to the EDTA treatment. When LCDGP was used, the compressive strength decreased owing to a decrease in packing density; however, the compressive and tensile strengths of Ultra-high-performance fiber-reinforced-concrete (UHPFRC) were improved on using nanosilica. It was observed that the surface modification of the fiber increased the friction force between the UHPC and fiber interface; therefore, it was more effective in improving the tensile strength than the compressive strength.

The antifungal potential of the chelating agent EDTA against postharvest plant pathogen Botrytis cinerea

Botrytis cinerea is a phytopathogenic fungus that causes gray mold, a major postharvest disease of fruits and vegetables. Chemical fungicides remain the main solution to control Botrytis disease, but concerns have raised about their safety to environment and human health, and there is an increasing need for development of more effective and less toxic treatments. In this study the divalent cation chelating agent ethylenediaminetetraacetic acid (EDTA) exhibited marked antifungal activity against B. cinerea, including inhibition of spore germination, mycelial growth, infection cushion formation, stimulation of cell death, and impairment of fungal virulence. These adverse effects of EDTA could be reversed by the addition of calcium ion, implying that metal ion chelation is involved in the fungicidal mechanism. Bean leaf and tomato fruit protection assay indicated that EDTA treatment led to a significant reduction of infection by B. cinerea. Furthermore, the antifungal activity of EDTA was significantly enhanced when used in combination with fenhexamid. These findings suggest that EDTA could be a promising tool to control B. cinerea, and application of EDTA may reduce the use of conventional chemical fungicides.

Impact of Irrigation with Wastewater on Accumulation of Heavy Metals in Phaseolus vulgaris L. and Its Remediation

This study investigates the effects of Spirulina platensis, Chlorella vulgaris, leaves powder of Salix alba, and ethylenediaminetetraacetic acid treatments on the biochemical and yield traits of Phaseolus plants grown under wastewater irrigation. In addition, to assess the uptake and accumulation of heavy metals into the edible plant part. Water samples were obtained from each irrigation source (fresh tap water and untreated wastewater collected from El-Rahawy drain, Giza, Egypt); the plants were treated with our treatments (3 g per kg soil) at the beginning of the experiment (mixed fully into the soil). The results observed that the irrigation of Phaseolus plants with wastewater markedly stimulated the free proline contents, total phenols, superoxide dismutase, catalase, peroxidase, polyphenol oxidase, lipid peroxidation, and abscisic acid throughout the two growth stages. Indole acetic acid, gibberellic acid, yield parameters, total soluble carbohydrate, and protein in seeds were significantly reduced. The concentrations of nickel (Ni), cadmium (Cd), lead (Pb), and cobalt (Co) in Phaseolus seeds were significantly increased beyond recommended limits set by international organizations. However, our treatments significantly reduced the contents of Ni, Cd, Pb, and Co in seeds; free proline; total phenols; superoxide dismutase; catalase; peroxidase; polyphenol oxidase; lipid peroxidation; and abscisic acid in Phaseolus plants. Moreover, indole acetic acid, gibberellic acid, all yield traits, and seed components were enhanced. This study concluded that Spirulina platensis and salix leaves powder being economically and environmentally friendly can be considered an efficient strategy to mitigate the harmful effects of wastewater on plants.

Use of engineered steel fibers as reinforcements in ultra-high-performance concrete considering corrosion effect

The feasibility of using steel fibers engineered through a hybrid treatment of ethylenediaminetetraacetic acid (EDTA)–electrolyte solution and nano-SiO2 coating as reinforcements for ultra-high-performance concrete (UHPC) was investigated by considering fiber corrosion effect. For this purpose, two different corrosion degrees of 2% and 5% were intentionally induced, and the interfacial bonding and tensile properties of UHPCs reinforced with plain and surface-reformed (or engineered) steel fibers were evaluated according to the degree of corrosion. The test results indicated that the EDTA–electrolyte solution treatment and nano-SiO2 coating are effective for improving the interfacial bonding of straight steel fibers in UHPC, leading to an 86% increase in the equivalent bond strength (24.7 MPa). The treatments also improved the tensile performance of ultra-high-performance fiber-reinforced concrete (UHPFRC), and more than twice higher energy absorption capacity could be achieved using the hybrid treatment method. In the case of plain steel fibers, the pullout resistance and tensile performance of UHPFRC both increased with fiber corrosion of up to 5%. However, UHPFRCs with surface-reformed steel fibers exhibited performance deterioration beyond a certain degree of corrosion. A longer immersion duration in the EDTA–electrolyte solution caused a higher susceptibility to steel fiber corrosion, regardless of the nano-SiO2 coating. Thus, fiber corrosion in UHPFRC must be prevented more strictly when surface-reformed steel fibers are used.

Technical note: Examining the use of ethylenediaminetetraacetic acid for humic extraction of ancient bone

We examined the efficacy of ethylenediaminetetraacetic acid (EDTA) for removing humic contaminants from collagen extracted from ancient bone. Humic contaminants must be removed to obtain reliable stable isotope values from ancient bone collagen, given that humic acids have consistently lower δ13C values than collagen. The purpose of our research was to examine if EDTA treatment could effectively remove humic contaminants from bone collagen and thus serve as an alternative to the commonly implemented sodium hydroxide (NaOH) treatment, which may be associated with large collagen losses in poorly preserved samples. We compared the isotopic and elemental composition of ancient samples treated with EDTA alone, samples demineralized in hydrochloric acid (HCl) and rinsed in EDTA, samples treated with HCl alone, and samples demineralized in HCl and rinsed with NaOH. The samples used in the analyses were selected because they presented evidence of substantial humic contamination. We found that NaOH was the most effective agent for reducing humic contaminants as evidenced by the samples treated with this agent having higher δ13C values and lower C:N ratios relative to other treatments. The results from samples treated with EDTA suggest that this chemical cannot effectively remove humic contaminants given that these samples had significantly higher C:N ratios and lower δ13C and δ15N values relative to the HCl/NaOH treatment. Our results demonstrate that when performing stable isotope analysis of ancient bone collagen suspected to be contaminated with humic acids, NaOH is the most effective chemical agent to remove humic contaminants, while EDTA cannot perform this task.

Effects of chelates (EDTA, EDDS, NTA) on phytoavailability of heavy metals (As, Cd, Cu, Pb, Zn) using ryegrass (Lolium multiflorum Lam.).

This paper summarises a study of the application of the synthetic chelate ethylenediaminetetraacetic acid (EDTA), and the natural chelates ethylenediamine-N,N'-disuccinic acid (EDDS) and nitrilotriacetate (NTA) to enhance ryegrass (Lolium multiflorum Lam.) uptake of the heavy metal(oid)s (HMs) (As, Cd, Cu, Pb and Zn) from contaminated soils in mining sites. The study compares the effects of these chelates (EDTA, EDDS and NTA) on the phytoavailability of HMs (As, Cd, Cu, Pb, Zn) using ryegrass (Lolium multiflorum Lam.) through the single addition and sequential addition methods. The results show that application of EDTA, EDDS and NTA significantly increases ryegrass (Lolium multiflorum Lam.)'s shoot uptake of some HMs when compared with no EDTA, EDDS or NTA application, particularly through sequential chelate treatment (EDTA 0.5:1+0.5:1; NTA 0.5:1+0.5:1; EDDS 0.5:1+0.5:1). EDTA 0.5:1+0.5:1 was more effective at increasing the concentration of Pb in shoots than were the other chelates (EDDS and NTA) and controls. Moreover, the concentrations of Zn in the shoots of ryegrass (Lolium multiflorum Lam.) in Hich Village significantly increased with the application of split dose (0.5:1+0.5:1). The plants displayed symptoms of toxicity including yellow and necrotic leaves at the end of the experiment. The selected chelates (EDTA, EDDS and NTA) led to a significant decrease in plant biomass (yield) 28 days after transfer with a maximum decrease in EDTA treatment (0.5:1+0.5:1) soils. This decrease was 3.43-fold in Ha Thuong, 3-fold in Hich Village and 1.59-fold in Trai Cau, respectively, relative to the control. HM concentration and dissolved organic carbon (DOC) in pore water provided an explanation for why fresh weight was significantly reduced with application of chelates in sequential dose (EDTA 0.5:1+0.5:1 and NTA 0.5:1+0.5:1).