Ethylenediaminetetraacetic Acid Research Articles

Oxide‐Encapsulated Silver Electrocatalysts for Selective and Stable Syngas Production from Reactive Carbon Capture Solutions

AbstractElectrolysis of bicarbonate‐containing CO2 capture solutions is a promising approach towards achieving low‐cost carbon‐neutral chemicals production. However, the parasitic bicarbonate‐mediated hydrogen evolution reaction (HER) and electrode instability in the presence of trace impurities remain major obstacles to overcome. This work demonstrates that the combined use of titanium dioxide (TiO2) overlayers with the chelating agent ethylene diamine tetra‐acetic acid (EDTA) significantly enhances the selectivity and stability of Ag‐based electrocatalysts for bicarbonate electrolysis. The amorphous TiO2 overlayers suppress the HER by over 50 % at potentials more negative than −0.7 V vs. RHE, increasing the CO faradaic efficiency (FE) by 33 % (relative). In situ surface‐enhanced Raman spectroscopy (SERS) measurements reveal the absence of near‐surface bicarbonate species and an abundance of CO2 reduction intermediates at the Ag|TiO2 buried interface, suggesting that the overlayers suppress HER by blocking bicarbonate ions from reaching the buried active sites. In accelerated degradation tests with 5 ppm of Fe(III) impurity, the addition of EDTA allows stable CO production with >47 % FE, while the electrodes rapidly deactivate in the absence of EDTA. This work highlights the use of TiO2 overlayers for enhancing the CO : H2 ratio while simultaneously protecting electrocatalysts from impurities likely to be present in “open” carbon capture systems.

Evaluation of Physical Properties in Carboxymethyl Chitosan Modified Glass Ionomer Cements and the Effect for Dentin Remineralization: SEM/EDX, Compressive Strength, and Ca/P Ratio.

The aim of this article was to evaluate the effects of modifying glass ionomer cement (GIC) with carboxymethyl chitosan (CMC) on surface morphology and remineralization outcomes by examining dentin morphology and calcium ion composition changes. Thirty holes in a cylindrical acrylic mold were filled with three groups of restorative materials: GIC, GIC modified with CMC (GIC-CMC) 5%, and GIC-CMC10%. The surface morphology of each group's materials was observed using scanning electron microscopy (SEM). The compressive strength measurement was performed using a universal testing machine. The dentin remineralization process was performed by applying GIC, GIC-CMC5%, and GIC-CMC10% materials for 14 days on demineralized dentin cavities treated with 17% ethylenediamine tetraacetic acid (EDTA) for 7 days. A morphological evaluation was conducted using SEM. The calcium ion composition and calcium-to-phosphorous (Ca/P) ratio were examined using an energy-dispersive X-ray (EDX). The Kruskal-Wallis and post-hoc Mann-Whitney U tests were performed to compare all four groups of calcium ions (p < 0.05). The modification of GIC with CMC affected the morphological changes in the materials in the form of reduced porosity and increased fractures. A significant difference was found in compressive strength between the GIC-CMC modification materials of GIC-CMC5% and GIC-CMC10% and the GIC control group. The dentin tubule morphology and surface changes were observed after applying GIC, GIC-CMC5%, and GIC-CMC10% materials for 14 days, as evaluated by SEM. The EDX examination showed an increase in calcium ion content and hydroxyapatite formation (Ca/P ratio) after applying the GIC-CMC10% material. The surface porosity of the GIC modification material with the addition of CMC tended to decrease. However, an increase in cracked surfaces that widened, along with the rise in CMC percentage, was found. This modification also reduced the compressive strength of the materials, with the lowest average yield at 10% CMC addition. Therefore, the modification of GIC with CMC affects changes in morphology, calcium ion composition, and Ca/P ratio in demineralized dentin.

Can ethylene diamine tetra-acetic acid improve calcium fracture when combined with intravascular lithotripsy?

Key points Agents which dissolve hydroxyapatite may synergize with intravascular lithotripsy (IVL) to treat calcium plates more extensively, facilitating greater penetration of drug‐coated balloons delivered agents and maintain gain in lumen area without stenting. Dissolving hydroxyapatite could potentially allow more frequent use of high‐pressure balloons without IVL or atherectomy to fracture calcium plates, offering a lower cost approach. Other mechanisms such as debonding between calcium plate and fibrous tissue junctions may also be enhanced with IVL and calcium‐modifying agents to improve calcified vessel compliance.

Evaluation of smear layer and Ca/P ratio in intra-radicular dentine irrigated with different irrigants adjunct with diode laser

BackgroundThis study aims to determine the smear layer removal from the root canals using different irrigant solutions with diode laser.MethodsA set of sixty human upper incisor teeth were chosen. Access cavity preparation was done followed by canal instrumentation. Samples were divided into six groups (Group A: sodium hypochlorite NaOCl, Group B: NaOCl + diode laser, group C: NaOCl + EDTA ethylene diamine tetra-acetic acid solution, Group D: NaOCl + EDTA + diode laser, Group E: NaOCl + garlic extract, Group F: NaOCl + garlic extract + diode laser. Examining the smear layer removal at the coronal, middle and apical thirds of the root canals was done by using electron microscope analysis. Using an energy-dispersive X-ray, the calcium/phosphorus Ca/P ratio was measured.ResultsAmong the examined groups, there were not any significant differences regarding the smear layer removal. The elimination of smear layers at the middle and coronal thirds was greater in all examined groups than in the apical third. EDX analysis revealed no statistically significant variation between the tested groups.ConclusionsUsing diode laser with sodium hypochlorite and ethylene diamine tetra-acetic acid irrigant solution was more effective for the elimination of smear layers. Garlic extract could be used as an alternative irrigant solution in debris removal.

In situ Ion Pumping Anodization to Confine Single‐Atom Fe onto TiO2 Nanotubes for Enhanced Noble‐Metal‐Free Photocatalytic Hydrogen Generation

AbstractAchieving a high dispersity of deposited transition metal is crucial in the anodization preparation of noble‐metal‐free composites for photocatalytic hydrogen generation. Herein, for the first time, an in situ ion pumping anodization method is proposed to confine single‐atom Fe within the spatially ordered structure of anodized TiO2 nanotubes (TNT), assisted by ferric sodium salt of ethylenediaminetetraacetic acid (EDTA) as an “ion pump” to deliver Fe3+ toward anodes. Both experimental and theoretical calculations confirm that highly dispersed single‐atom Fe can interact with single‐electron‐trapped oxygen vacancies (SETOV), effectively reducing the oxygen vacancy concentration in TiO2 nanotubes. This reduction promotes efficient charge carrier separation through the Fe(III)/Fe(II) pathway and enhances hydrogen desorption, ultimately boosting the photocatalytic hydrogen evolution performance.

Bis(ethylenediammonium) μ-ethylenediaminetetraacetato-1κ3 O,N,O′:2κ3 O′′,N′,O′′′-bis[trioxidomolybdate(VI)] tetrahydrate

The title compound, (C2H10N2)2[(C10H12N2O8)(MoO3)2]·4H2O, which crystallizes in the monoclinic C2/c space group, was obtained by mixing molybdenum oxide, ethylenediamine and ethylenediaminetetraacetic acid (H4edta) in a 2:4:1 ratio. The complex anion contains two MoO3 units bridged by an edta4− anion. The midpoint of the central C—C bond of the edta4− anion is located on a crystallographic inversion centre. The independent Mo atom is tridentately coordinated by a nitrogen atom and two carboxylate groups of the edta4− ligand, together with the three oxo ligands, producing a distorted octahedral coordination environment. In the three-dimensional supramolecular crystal structure, the dinuclear anions, the organoammonium counter-ions and the solvent water molecules are linked by N—H...Ow, N—H...Oedta and O—H...O hydrogen bonds.

Supercritical hydrothermal synthesis of ultra-fine Cu powders

ABSTRACT Ultra-fine Cu powders were synthesized using supercritical water as a reaction medium and formic acid as a reducing agent. The effects of reducing agent, reaction temperature, and complexing agent on the phase constituents, particle size distributions and morphology of the synthesized ultra-fine Cu powders were investigated. A complex mixture of Cu2O and Cu powders formed by pure supercritical water while high purity homogeneous ultra-fine Cu powders can be synthesized by supercritical water with formic acid as a reducing agent. Moreover, fine tuning of particle size and morphology can be realized by the addition of Ethylenediamine tetraacetic acid (EDTA). The modification mechanism of EDTA on the surfaces of ultra-fine Cu powders was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. EDTA adsorbed on the surfaces of nanoparticles by the dehydration reaction of carboxyl groups in the molecule of EDTA and hydroxyl groups on surfaces of copper nanoparticles (CuOH).

Antibacterial Efficacy of Graphene Nanoparticles against Enterococcus faecalis: In Vitro Study.

This study compared the antimicrobial efficacy of nanographene (NG) particles with chlorhexidine (CHX) and calcium hydroxide (Ca(OH)2) against Enterococcus faecalis. Forty extracted human mandibular premolar teeth were cleaned using a scaler, and the middle-third of the root (6 mm) was decoronated using a rotary diamond disk. The inner diameter of the teeth was made consistent using Gates Glidden Drills #3, treated with ethylene diamine tetra-acetic acid and sodium hypochlorite before sterilization. The samples were then contaminated with E. faecalis grown in Tryptic soy broth for 21 days. Tooth samples were then randomly divided into four groups: Group I (Control), untreated saline; Group II, Ca(OH)2; Group III, CHX; and Group IV, NG. The assessment of bacterial growth was carried out by harvesting dentin chips at the end of 1, 3, and 7 days. The colonies were physically counted and tabulated after 24 hours from seeding. Statistical analysis of the collected data was performed with analysis of variance and Tukey's post hoc test using SPSS Version 20.0. The contaminated dentine blocks irrigated with NG (0.5 µg) and CHX (0 ± 0; p < 0.001) had no growth of E. faecalis colonies compared to blocks of Ca(OH)2 (10 ± 21) and saline (927 ± 455). All concentrations of NG (0.5 and 1.0 µg) showed effectiveness higher (p < 0.001) than 2% CHX when measured by the zone of inhibition against E. faecalis. CONCLUSION: It may be concluded that NG is effective against growth of E. faecalis and may be used as a promising antimicrobial agent during root canal treatment. However, further studies should be done to investigate the effect of NG against other dental pathogens.

With Blue Light against Biofilms: Berberine as Natural Photosensitizer for Photodynamic Inactivation of Human Pathogens

Evolving antibiotic resistance of bacteria is a prevailing global challenge in health care and requires the development of safe and efficient alternatives to classic antibiotics. Photodynamic Inactivation (PDI) has proven to be a promising alternative for treatment of a broad range of microorganisms. Photodynamic Inactivation uses photoactive molecules that generate reactive oxygen species (ROS) upon illumination and in the presence of oxygen, which immediately kill pathogenic target organisms. Relevant photoactive properties are provided by berberine. Originally extracted from Barberry (Berberis vulgaris), it is a natural compound widely used in Traditional Chinese Medicine for its antimicrobial and anti-inflammatory effects. With this study, we demonstrated the potential of berberine chloride hydrate (Ber) as a photosensitizer for PDI of important human pathogens, Gram(+) Staphylococcus capitis subsp. capitis, Gram(+) Staphylococcus aureus, and Gram(−) Escherichia coli. In vitro experiments on planktonic and biofilm cultures were conducted focusing on Ber activated with visible light in the blue wavelength range. The number of planktonic S. capitis cells was reduced by 7 log10 steps using 100 µM Ber (5 min incubation, illumination with 435 nm LED array, radiant exposure 25 J/cm2). For an antibacterial effect of 4 log10 steps, static S. capitis biofilms required 1 mM Ber, a drug-to-light interval of 60 min, and illumination with 100 J/cm2. Almost all planktonic cells of Staphylococcus aureus could be photokilled using 100 µM Ber (drug-to-light interval of 30 min, radiant exposure 25 J/cm2). Biofilms of S. aureus could be phototreated (3 log10 steps inactivation) when using 1 mM Ber incubated for 5 min and photoactivated with 100 J/cm2. The study is highlighted by the proof that PDI treatment using Ber showed an antibacterial effect on Gram(−) E. coli. Planktonic cells could be reduced by 3 log10 steps with 100 µM Ber (5 min incubation, 435 nm, 25 J/cm2). With 5 mM ethylenediamine tetraacetic acid disodium salt dihydrate (Na2EDTA) or 1.2% polyaspartic acid (PASA) in addition, a relative inactivation of 4 log10 steps and 7 log10 steps, respectively, was detectable. Furthermore, we showed that an antibacterial effect of 3.4 log10 towards E. coli biofilms was given when using 1 mM Ber (5 min incubation, 435 nm, 100 J/cm2). These results underscore the significance of PDI-treatment with Ber as a natural compound in combination with blue light as valuable antimicrobial application.

Evaluation of Fracture Strength of Roots to Determine the Duration Limit of Activated Ethylene Diamine Tetraacetic Acid Irrigation for Intracanal Calcium Hydroxide Dressing Removal In Vitro

This study evaluated the effect of the use of EDTA solution at various intervals to remove intracanal calcium hydroxide medication on fracture resistance. One hundred and one extracted lower premolar teeth were randomly allocated into one control group (n = 5), two main experimental groups (CH(+), with calcium hydroxide dressing, and CH(−), without calcium hydroxide dressing), with four subgroups (EDTA intervals: 1 min, 3 min, 5 min, 10 min, n = 12). Ready-to-use injectable calcium hydroxide was used for the samples in the four CH(+) subgroups, and the samples were kept in an incubator at 37 °C and 100% humidity for seven days. All samples (CH(+), CH(−)) were irrigated with 17% EDTA, which was accompanied by activation with EndoActivator for 1, 3, 5, and 10 min, and then rinsed with 2.5% NaOCl in a standardized manner. The obturation was conducted using the warm obturation technique; experiments were conducted with a universal testing device, and their fracture strength was recorded. Compliance with the normal distribution was examined with ±2 skewness coefficients. Two-way ANOVA, Tukey’s, one-way ANOVA, and Dunnett’s tests were used for statistics (p &lt; 0.050). A statistically significant difference was found between the mean values of the force between the groups (p = 0.009). The mean strength of the tooth at fracture that CH(−) was 401.7, CH(+) was 335.35. There was no statistically significant difference between the mean values of the forces according to time intervals (p = 0.387). While there was no significant difference among the experimental groups (p = 0.229), the mean fracture strength of the negative control group was found to be significantly higher (p &lt; 0.001). The highest fracture resistance was observed in the nonprepared group. Irrigation with EDTA for up to 5 min showed more acceptable fracture resistance results than the other groups. Using calcium hydroxide significantly and negatively affected the root strength.

A modified pararosaniline hydrochloride method for determination of total and bound sulfur dioxide in wine

An improved pararosaniline hydrochloride (PRA) method for rapid and accurate determination of total and bound sulfur dioxide (SO2) in wine was established. The determination conditions for total SO2 were optimized in model wine systems. The pH of the acidified PRA reagent had a significant effect on the color and the maximum absorption wavelength (λmax) of the reaction system, with its optimum pH 0.48 and a λmax at 549 nm. The addition of ethylene diamine tetraacetic acid (EDTA) could effectively shield the interference of coexisting metal ions present in wine, and a novel approach to double background subtraction was confirmed to remove the matrices interference of red wine color. Under the optimum conditions, the linear range for total SO2 in wine was within 1.00–8.00 mg L−1 (R = 0.9975), with the detection and quantification limits (MDL and MQL) found as 0.02 and 0.06 mg L−1, respectively. The recovery of SO2 ranged from 85.73 % to 105.70 % with the relative standard deviations (RSD) of 0.21 % - 7.78 %, suggesting high sensitivity and accuracy of the method. Combining with the optimized Monier-Williams method, the determination of bound SO2 in wine was also achieved. Sulfite determination can be performed in wine using the rapid, accurate and sensitive method without any pretreatment, and the results were comparable with those of the standard methods.

Effect of herbal irrigants on surface roughness of intraradicular dentin using quantitative method of 3D surface texture analysis

Replacing the conventional endodontic irrigants with herbal agents could avoid complications associated with using sodium hypochlorite (NaOCl). Endodontic irrigants alter the surface roughness of the dentinal wall surface, which affects sealer mechanical retention. This study aimed to assess the effect of experimental herbal Moringa oleifera and orange peel extract irrigant on intraradicular dentin (IRD) surface roughness using quantitative 3D surface analysis by scanning electron microscopy (SEM) regarding the smear layer assessment. Sixty human root sections were divided into four groups (n = 15): NaOCl combined with 17% ethylenediaminetetraacetic acid (EDTA); negative control (saline); moringa extract (MO); and orange oil (OO). SEM images were assessed quantitatively for surface roughness (Ra) in the coronal, middle, and apical IRD. The data were analysed by Kruskal–Wallis, Friedman, and Dunn’s tests. All groups showed statistically significant differences (P = 0.007). MO exhibited significantly greater Ra values at the coronal, middle, and apical root levels than OO (P = 0.007, 0.009, and 0.046, respectively). There was no significant change in Ra values at various root levels within each group at P = 0.091, 0.819, 0.819, and 0.549 for the EDTA, saline, MO, and OO groups. Considerable (IRD) surface roughness analysis makes Moringa extract a promising herbal endodontic irrigant alternative to the NaOCl plus EDTA regimen.

Fluorescent and colorimetric dual-mode chemosensor for easy detection of Cu2+: Practical and smartphone-based application to test strip and water sample

A fluorescent and colorimetric dual-mode chemosensor HNHQ, based on the julolidine and naphthol moieties, was synthesized. Compound HNHQ exhibited unique photophysical properties of an intense fluorescence with a high quantum yield (Φ = 0.363) and a light yellow color through the ICT mechanism. HNHQ could detect Cu2+ through both a fluorescence turn-off and a colorimetry variation of light yellow to yellowish brown. HNHQ reacted with Cu2+ with a binding ratio of 1:1. The detection limit for Cu2+ was analyzed to be 1.60 μM for fluorescence and 1.32 μM for UV–vis, considerably below the safe value of 31.5 μM established by the World Health Organization (WHO). HNHQ analyzed Cu2+ in the pH range of 6–8 and reversibly identified Cu2+ by using ethylenediaminetetraacetic acid (EDTA). Moreover, HNHQ could effectively detect Cu2+ in mineral and tap water samples, in addition to test strips through fluorescent and colorimetric changes. As a portable probe, HNHQ was successfully applied to a smartphone-based RGB analysis for the quantitative examination of Cu2+. The detection mechanism of HNHQ for Cu2+ was illustrated by 1H NMR titration, ESI-MS analysis, and density functional theory (DFT) calculations.

Lead Tolerance and Remediation Potential of Four Indocalamus Species in Lead-Contaminated Soil.

Indocalamus plants are low-growing shrubby bamboos with growth advantages, such as high biomass and strong resistance, and they are rich in germplasm resources in southern China. This study conducted soil lead (Pb) stress experiments on Indocalamus latifolius (Keng) McClure (LA), Indocalamus hunanensis B.M. Yang (HU), Indocalamus chishuiensis Y.L. Yang and Hsueh (CH) and Indocalamus lacunosus Wen (LC). Five Pb treatments (0, 500, 1000, 1500 mg·kg-1 Pb, and 1000 mg·kg-1 Pb + 1000 mg·kg-1 ethylenediamine tetraacetic acid (EDTA)) were established. EDTA was applied to explore the tolerance mechanism of different Indocalamus species after absorbing large amounts of heavy metals. The results were as follows: (1) under Pb treatment, the total relative biomass of LA, HU and LC was <100%, whereas the total relative biomass of CH was >100%; (2) after applying EDTA, the bioconcentration coefficient, translocation factor, and free proline content of the four Indocalamus species increased; and (3) the Pb mobility and distribution rates of the underground parts of the four Indocalamus species were consistently greater than those of the aboveground parts. The Pb mobility and distribution rates in the stems increased after applying EDTA, while those in the leaves decreased, as the plants tended to transfer Pb to their stems, which have lower physiological activity than their leaves.

Understanding Microscopic Interactions in Binding Reactions: The pH Titration of EDTA

ABSTRACT Students beginning the study of biochemistry or biophysics at the undergraduate or even early graduate level are often overwhelmed by the complexity of the systems and the nomenclature. By comparison, chemical systems appear simple, as students can more easily relate to introductory chemistry courses, where the molecules are smaller and bind yet smaller ions. This allows students to write the structure of the entire molecule on a piece of paper and see exactly to which functional groups an ion, such as a proton (H+) in the simplest case, binds. Yet, concepts that are fundamental in biochemical macromolecules, namely proteins, can perfectly well be taught at the undergraduate or beginning graduate level, and probably be more easily understood, by using simpler, familiar chemical examples. The concept of interacting binding sites, which is at the root of cooperativity in protein binding reactions and conformational changes, is already present in simple molecules, such as ethylenediaminetetraacetic acid (EDTA). In this article, we show how to teach these topics by using the idea of the partition function, rather than a formal algebraic approach, to treat the binding of protons to EDTA. Profound concepts, such as that of interacting sites, appear naturally in a small molecule, where the origin can be easily ascribed, in this case, mainly to electrostatic interactions. Equipped with this understanding and this approach, students will be able to tackle more complicated biochemical systems, in which the molecules are larger, but the concepts are the same.

Effects of Endodontic Irrigants on Shear Bond Strength of Mild Universal Adhesives to Dentin

PurposeThe objective of this in vitro study was to evaluate the shear bond strength (SBS) of several universal adhesives to dentin treated with sodium hypochlorite (NaOCl), and NaOCl followed by ethylenediaminetetraacetic acid (EDTA). Materials and MethodsAdhese Universal (ADU), Scotchbond Universal (SBU), Prime & Bond Elect (PBE), Prime & Bond Active (PBA), and Optibond XTR (OBX) were included in the study. SBS values were determined in self-etch mode with no pretreatment of the dentin, after a twenty-minute exposure of the dentin to 6% NaOCl, and after a twenty-minute exposure to NaOCl followed by a one-minute exposure to 17% EDTA. Experimental groups were repeated using a total-etch technique (except OBX). ResultsAdhesives in self-etch mode had significantly reduced SBS following dentin exposure to NaOCl (p<0.05), while with a total-etch technique only PBA was affected (p<0.05). SBS in self-etch mode when NaOCl exposure was followed by EDTA were equal to or higher than negative control values (p<0.05). For total-etch groups, ADU was negatively affected by NaOCl + EDTA exposure (p<0.05). PBE exhibited lower SBS following NaOCl + EDTA exposure when compared to just NaOCl exposure but was not different from the negative control (p<0.05). ConclusionFor the adhesives tested, the use of 17% EDTA following NaOCl exposure negated the negative effects of NaOCl on SBS in self-etch mode. When used in total-etch mode, results varied significantly, with some adhesives performing better or worse depending on the specific testing condition.

An in vitro comparative evaluation of cyclic fatigue resistance of two rotary and two reciprocating file systems

Context: Root canal instrumentation is one of the important procedures for successful endodontic therapy. Unexpected fracture of files occurs during root canal instrumentation without any visible signs of deformation compromising the success of root canal treatment. Aims: The aim of the study was to evaluate and compare cyclic fatigue resistance (CFR) of rotary and reciprocating files in simulated canals with 45°, 60°, and 90° angle of curvature. Settings and Design: The study design was an In vitro study. Subjects and Methods: Sixty nickel–titanium files, 30 each of rotary and reciprocating files were selected and divided into four groups (n = 15) of Neoendo Flex, ProTaper Next, WaveOne Gold (WOG), and Reciproc Blue (RPB) files. Each group was further subdivided into three subgroups containing five samples each based on their use in simulated canals with 45°, 60°, and 90° angle of curvature. To simulate root canals with 45°, 60°, and 90° angle of curvature, three artificial canals were designed in a stainless steel metal block. Each file was autoclaved, immersed in 3% sodium hypochlorite (NaOCl), and coated with 17% ethylenediaminetetraacetic acid (EDTA). Each file was tested for CFR using a torque-controlled reduction handpiece by instrumenting in a simulated canal for 10 s until fracture. The cycle of autoclaving, exposure to NaOCl, EDTA, and testing of CFR for 10 s per canal as per groups and subgroups was repeated again and again until the respective file fracture. The time taken to file fracture was recorded using a digital chronometer. The time taken for each file fracture (in minutes) was multiplied by the number of rotations per minute to attain the number of cycles to failure (NCF). Statistical Analysis Used: The obtained results were subjected to statistical analysis using one-way analysis of variance and independent t-test. Results: One-way ANOVA test showed a statistically significant difference between the four groups, P &lt; 0.001. Independent “t”-test between individual subgroups showed a statistically significant difference, as P &lt; 0.05. Conclusions: WOG and RPB reciprocating file systems showed superior CFR, more especially in canals with abrupt 90° angle of curvature compared to both rotary file systems tested. Among rotary file systems tested, Neoendo Flex showed greater CFR than ProTaper Next.

Alleviation of RO membrane fouling in wastewater reclamation plants using an enhanced acid-base chemical cleaning method

Membrane fouling has always been a critical constraint in the operation of the reverse osmosis (RO) process, and chemical cleaning is essential for mitigating membrane fouling and ensuring smooth operation of the membrane system. This paper presents an optimized chemical cleaning method for the efficient cleaning of RO membranes in full-scale applications. Compared to the regular cleaning method (cleaning with 0.1 % NaOH + 1 % ethylenediaminetetraacetic acid + 0.025 % sodium dodecyl benzene sulfonate followed by 0.2 % HCl), the optimized cleaning method improves the cleaning efficiency by adding sodium chloride to the alkaline cleaning solution and citric acid to the acid cleaning solution. Notably, the membrane flux recovery rate with the optimized cleaning method is 45.74 %, and it improves the cleaning efficiency by 1.65 times compared to the regular cleaning method. Additionally, the optimized cleaning method removes 30.46 % of total foulants (organic and inorganic), which is 2.11 times higher than the regular cleaning method. The removal of inorganic ions such as Fe, Ca, and Mg is significantly improved with the optimized cleaning method. For organic matter removal, the optimized cleaning method effectively removes more polysaccharides, proteins, and microbial metabolites by disrupting the complex structures of organic matter. Furthermore, it also changes the microbial community structure on the RO membrane surface by eliminating microorganisms that cannot withstand strong acids, bases, and high salt environments. However, Mycobacterium can adapt to these harsh conditions, showing a relative abundance of up to 84.13 % after cleaning. Overall, our results provide a new chemical cleaning method for RO membranes in full-scale applications. This method effectively removes membrane foulants and enhances the understanding of the removal characteristics of foulants on RO membrane surfaces by chemical cleaning.

Baseline and stress-induced changes in plasma bacterial killing ability against gram-negative bacteria are partially mediated by the complement system in Rhinella diptycha toads

The plasma bacterial killing ability (BKA) is modulated by the stress response in vertebrates, including amphibians. The complement system is an effector mechanism comprised of a set of proteins present in the plasma that once activated can promote bacterial lysis. Herein, we investigated whether changes in plasma BKA as a result of the acute stress response and an immune challenge are mediated by the complement system in Rhinella diptycha toads. Additionally, we investigated whether the observed changes in plasma BKA are associated with changes in plasma corticosterone levels (CORT). We subjected adult male toads to a restraint or an immune challenge (with three concentrations of Aeromonas hydrophila heat inactivated), and then evaluated the plasma BKA against A. hydrophila, in vitro. We determined the complement system activity on plasma BKA, by treating the plasma (baseline, 1 h and 24 h post-restraint, and after the immune challenge) with ethylenediaminetetraacetic acid, heat, or protease. Our results showed increased CORT 1 h and 24 h after restraint and decreased plasma BKA 24 h post-restraint. The inhibitors of the complement system decreased the plasma BKA compared with untreated plasma at all times (baseline, 1 h, and 24 h after restraint), demonstrating that the plasma BKA activity is partially mediated by the complement system. The immune challenge increased CORT, with the highest values being observed in the highest bacterial concentration, compared with control. The plasma BKA was not affected by the immune challenge but was demonstrated to be partially mediated by the complement system. Our results demonstrated that restraint and the immune challenge activated the hypothalamus-pituitary-interrenal axis, by increasing plasma CORT levels in R. diptycha. Also, our results demonstrated the complement system is participative in the plasma BKA for baseline and post-stress situations in these toads.

Fluorescent and colorimetric dual-mode chemosensor for easy detection of Cu2+: Practical and smartphone-based application to test strip and water sample

A fluorescent and colorimetric dual-mode chemosensor HNHQ, based on the julolidine and naphthol moieties, was synthesized. Compound HNHQ exhibited unique photophysical properties of an intense fluorescence with a high quantum yield (Φ = 0.363) and a light yellow color through the ICT mechanism. HNHQ could detect Cu2+ through both a fluorescence turn-off and a colorimetry variation of light yellow to yellowish brown. HNHQ reacted with Cu2+ with a binding ratio of 1:1. The detection limit for Cu2+ was analyzed to be 1.60 μM for fluorescence and 1.32 μM for UV–vis, considerably below the safe value of 31.5 μM established by the World Health Organization (WHO). HNHQ analyzed Cu2+ in the pH range of 6–8 and reversibly identified Cu2+ by using ethylenediaminetetraacetic acid (EDTA). Moreover, HNHQ could effectively detect Cu2+ in mineral and tap water samples, in addition to test strips through fluorescent and colorimetric changes. As a portable probe, HNHQ was successfully applied to a smartphone-based RGB analysis for the quantitative examination of Cu2+. The detection mechanism of HNHQ for Cu2+ was illustrated by 1H NMR titration, ESI-MS analysis, and density functional theory (DFT) calculations.