Ethylenediaminetetraacetic Acid Solution Research Articles

Chromium(III) Removal from Wastewater by Chitosan Flakes

Chitosan is very effective in removing metal ions through their adsorption. A preliminary investigation of the adsorption of chromium(III) by chitosan was carried out by means of batch tests as a function of contact time, pH, ion competition, and initial chromium(III) concentration. The rate of adsorption was rather rapid (t1/2 < 18 min) and influenced by the presence of other metal ions. The obtained data were tested using the Langmuir and Freundlich isotherm models and, based on R2 values, the former appeared better applicable than the latter. Chitosan was found to have an excellent loading capacity for chromium(III), namely 138.0 mg Cr per g of chitosan at pH = 3.8, but metal ions adsorption was strongly influenced by the pH. About 76% of the recovered chromium was then removed simply by washing the used chitosan with 0.1 M EDTA (Ethylenediaminetetraacetic acid) solution. This study demonstrates that chitosan has the potential to become an effective and low-cost agent for wastewater treatment (e.g., tannery waste) and in situ environmental remediation.

Surface charge study of EDTA interaction with carbonate rock during chelating agent flooding

Altering the carbonate wettability is considered as an effective approach for enhancing the oil recovery from carbonate reservoirs. Wettability alteration from oil-wet to more water-wet condition can be assessed by studying the changes in rock surface charges. In this study, the surface charges of carbonate rock samples during chemical flooding is investigated. The impact of flooding carbonate rocks with Ethylenediaminetetraacetic acid (EDTA) on changing the surface charges and increasing the oil recovery is studied. The effect of brine salinity, EDTA concentrations and solution pH on the oil recovery is discussed. The performance of EDTA solution was compared with high-salinity seawater (SW), diluted seawater (50%SW) and deionized water. Results of zeta potential measurements, ions concentrations analysis, nuclear magnetic resonance, spontaneous imbibition and coreflooding experiments are reported in this paper. The rock samples were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses. SARA analysis, gas-chromatography (GC) and rheological measurements were performed to characterize the crude oil. This study showed that injecting EDTA solutions into carbonate rocks can change the carbonate surface charges from positive to negative values indicating that the rock wettability was altered to more water-wet conditions, and consequently more oil was recovered during the coreflooding and the spontaneous imbibition tests. Incremental oil recovery of 20% was achieved by flooding the carbonate sample with EDTA solutions. During spontaneous imbibition tests, 80% of the oil was recovered using 5 wt% EDTA chelating agent, while 50% and 20% were recovered using deionized water and seawater brine, respectively. The ions concentrations analysis showed that the amount of calcium ions was significantly increased during the EDTA flooding, indicating that the injected chemicals increase the Ca2+ leaching from carbonate surface and improve the wettability conditions. Finally, NMR analysis confirmed that the injected chemicals did not induce severe bulk damage and only surface dissolution was taking place.

Cane Molasses Graphene Quantum Dots Passivated by PEG Functionalization for Detection of Metal Ions.

Poly(ethylene glycol) passivated graphene quantum dots (PEG-GQDs) were synthesized based on a green and effective strategy of the hydrothermal treatment of cane molasses. The prepared PEG-GQDs, with an average size of 2.5 nm, exhibit a brighter blue fluorescence and a higher quantum yield (QY) (up to approximately 21.32%) than the QY of GQDs without surface passivation (QY = 10.44%). The PEG-GQDs can be used to detect and quantify paramagnetic transition-metal ions including Fe3+, Cu2+, Co2+, Ni2+, Pb2+, and Mn2+. In the case of ethylenediaminetetraacetic acid (EDTA) solution as a masking agent, Fe3+ ions can be well selectively determined in a transition-metal ion mixture, following the lowest limit of detection (LOD) of 5.77 μM. The quenching mechanism of Fe3+ on PEG-GQDs belongs to dynamic quenching. Furthermore, Fe3+ in human serum can be successfully detected by the PEG-GQDs, indicating that the green prepared PEG-GQDs can be applied as a promising candidate for the selective detection of Fe3+ in clinics.

Using ultrasound to improve the sequential post-synthesis modification method for making mesoporous Y zeolites

Mesoporous Y zeolites were prepared by the sequential chemical dealumination (using chelating agents such as ethylenediaminetetraacetic acid, H4EDTA, and citric acid aqueous solutions) and alkaline desilication (using sodium hydroxide, NaOH, aqueous solutions) treatments. Specifically, the ultrasound-assisted alkaline treatment (i.e., ultrasonic treatment) was proposed as the alternative to conventional alkaline treatments which are performed under hydrothermal conditions. In comparison with the hydrothermal alkaline treatment, the ultrasonic treatment showed the comparatively enhanced efficiency (with the reduced treatment time, i.e., 5 min vs. 30 min, all with 0.2 mol·L−1 NaOH at 65°C) in treating the deal-uminated Y zeolites for creating mesoporosity. For example, after the treatment of a dealuminated zeolite Y (using 0.1 mol·L−1 H4EDTA at 100°C for 6 h), the ultrasonic treatment produced the mesoporous zeolite Y with the specific external surface area (Sexternal) of 160 m2·g·−1and mesopore volume (Vmeso) of 0.22 cm3·g−1, being slightly higher than that by the conventional method (i.e., Sextemal= 128 m2·g−1 and Vmeso = 0.19 cm3·g−1). The acidic property and catalytic activity (in catalytic cracking of n-octane) of mesoporous Y zeolites obtained by the two methods were comparable. The ultrasonic desilication treatment was found to be generic, also being effective to treat the dealuminated Y zeolites by citric acid. Additionally, the first step of chemical dealumination treatment was crucial to enable the effective creation of mesopores in the parent Y zeolite (with a silicon-to-aluminium ratio, Si/Al = 2.6) regardless of the subsequent alkaline desilication treatment (i.e., ultrasonic or hydrothermal). Therefore, appropriate selection of the condition of the chemical dealumination treatment based on the property of parent zeolites, such as Si/Al ratio and crystallinity, is important for making mesoporous zeolites effectively.

Microbiological study of the efficiency of root canal treatment with Er:yYAG laser

Mechanical and drug treatment of the root canal are the most important components of the success of endodontic treatment. This work presents the results on the effectiveness of the root canal disinfection using an erbium laser in combination with a 17% solution of ethylene diaminetetraacetic acid (EDTA) in vitro and in clinical studies. An in vitro study was carried out on removed intact teeth infected with strains of Enterococcus faecalis, Streptococcus sanguinis, and Candida albicans. An experimental group of teeth was treated medically according to a standard protocol using 3% solution of sodium hypochlorite and 17% solution of EDTA followed by irradiation with erbium laser. The control group was treated similarly but without laser irradiation. The treatment effectiveness was evaluated by the reduction of CFU. After the treatment, in the control group after the mechanical and drug treatment, the CFU amount lowered by 4 times, while the complete sterilization was observed in the experimental group. The clinical studies included two groups of 35 patients each diagnosed with chronic periodontitis. In the experimental group of patients, at the final stage, treatment with erbium laser for 1 min using endodontic piece (40 mJ power, 2940 nm wavelength, 10 Hz pulse rate) and a 17% EDTA solution was performed before filling. Periodontitis treatment in the control group was carried out without the laser treatment. The control group of patients saw the reduction on CFU after the mechanical and drug treatment by 3–6 times, while the experimental group achieved the complete sterilization of the root canals. The obtained results prove that the modification of the root canal treatment by the inclusion of erbium laser irradiation is a promising direction in endodontics.

Reaction Acceleration of Nanoporous High-Purity Pd Film Formation by Dealloying of Al-Pd-N Film in pH-Controlled EDTA Solution

AbstractMetallic palladium (Pd) is used for hydrogen storage and detection. Fabrication of a nanoporous (NP) Pd structure can increase the specific surface area leading to a significant improvement in the sensitivity. In our previous study, we succeeded in forming a NP-Pd film by dealloying an Al-Pd alloy film using citric acid as a chelating agent. This method was environmentally friendly but had a long reaction time and a considerable amount of Al remained after dealloying; hence, the Pd purity was reduced. In this study, we succeeded in forming a higher purity NP-Pd film faster by dealloying the nitrogen-containing Al-Pd (Al-Pd-N) film using ethylene-diamine-tetraacetic-acid (EDTA) as a chelating material.

Assesment to Increase the Mechanical Properties of used Ballast by Edta Solution as a Construction Material

Ballast is playing a vital role in taking the huge loads of railways which is strong, durable and also providing maximum stability to track/permanent way. Usually having a 40mm size ballast. The Shape of the ballast is important as its irregular shape and sharp edges help in the interlocking of themselves which gives more stability and passage of drainage. Within its lifetime the ballast used to get rounded edges, unable to stabilize or interlock and losses its strength for this reduction it should be replaced with new ballast. So the waste ballast is considered as our material to be tested in our project by adding the solution called EDTA (ETHYLENEDIAMINETETRAACETIC ACID) to develop the maximum properties of ballast by crushing them to 10mm, 12.5mm and 20mm size used for road construction. This work was conducted to determine the hardness, toughness, strength of aggregate using EDTA solution. The effectiveness of aggregate using of EDTA was studied in this project by adding required concentrations of 5%, 10% to the aggregates.

Changes in plasma pH and blood and urinary macromineral concentrations in experimentally induced hypocalcemic cows with Na2EDTA.

This study was performed to confirm the alterations of blood and urine parameters in artificially induced hypocalcemic cows. For a 2 × 2 cross-over design, four non-pregnant, non-lactating Holstein Friesian cows (623 ± 63 kg) were utilized. Cows in the treatment and control group were infused with ethylenediaminetetraacetic acid (Na2EDTA) solution and normal saline through an intravenous catheter for 3 hr, respectively. Laboratory analyses included complete blood cell count, plasma chemistry, blood gas analysis and urine chemistry. During the hypocalcemic period, abnormal signs were not observed clinically, hematologically nor biochemically either in groups. But, plasma calcium and magnesium concentrations continued to decrease throughout Na2EDTA infusion, and significant group differences (P<0.05 or P<0.001) were detected until 5 hr after the initiation of infusion. Urinary excretions of these minerals were significantly reduced compared to the control group by 6 hr (Ca, P<0.05; Mg, P<0.001). Moreover, there is a significant group difference in the change in plasma pH at 1 hr after Na2EDTA infusion (P<0.05) and maintained a decreased level until 6 hr. Consequently, the blood pH was diminished simultaneously with hypocalcemia and hypomagnesemia induction in cows infused with Na2EDTA. This phenomenon may be one of the mechanisms to recover normocalcemia including maximizing the effect of parathyroid hormone, however, further studies are needed to elucidate the mechanism to alter the blood pH in hypocalcemia.

Effect of different chelating agents on the bond strength of a silicone-based root canal sealer to root dentin.

Aim:The purpose of this study was to evaluate the impact of 7% maleic acid (MA), 17% ethylenediaminetetraacetic acid (EDTA) solution, 10% citric acid (CA), or 2.25% peracetic acid (PAA) on the dislodgment resistance of a silicone-based root canal sealer.Materials and Methods:Ninety-five mandibular incisors were shaped to size R50. The specimens were randomly assigned to the following five groups (n = 15) based on the final irrigation solution: 5% sodium hypochlorite (NaOCl), 17% EDTA, 7% MA, 10% CA, and 2.25% PAA. Four specimens from each group were examined under scanning electron microscope. All the remaining canals were obturated with GuttaFlow® Bioseal. Bond strength was assessed using the push-out test. The data were analyzed statistically by two-way analysis of variance and Bonferroni tests at the significance level of P = 0.05.Results:The roots irrigated with chelators showed statistically significantly higher bond strength than the roots irrigated with NaOCl (P < 0.05). Overall, MA showed the highest bond strength, but there was no statistically significant difference among the other chelating solutions (P > 0.05).Conclusions:The bond strength of the GuttaFlow Bioseal to the root canal dentin may increase by the removal of smear layer. Final irrigation with the investigated chelators resulted in similar bond strength of the GuttaFlow Bioseal.

Feasibility study for bone health assessment based on photoacoustic imaging method

This study investigated the feasibility of photoacoustic (PA) imaging of bone and characterization of bone features. By conducting the experiments on bovine femoral heads ex vivo, the light and ultrasonic penetration in bones was studied, together with the depth of PA imaging and measurement in bones. Then, the possibility of three-dimensional (3D) PA imaging of bones by raster scanning of the focusing transducer was studied. The micro-computerized tomography images of the bovine ribs with and without ethylenediaminetetraacetic acid (EDTA) treatment indicated that the 3D PA images could present the changes of bone microstructure resulting from the EDTA treatment. By using PA spectral analysis, the bone samples with and without the treatment of EDTA solution can be distinguished, and the microstructures can be characterized. This study was based on the bovine bone whose size is comparable to human bones, suggesting that PA technology can be used as a novel bone diagnostic technique.

Chitosan: A natural substitute of EDTA solution for final irrigation in endodontics treatment.

The purpose of this study was to assess the quantity of the chelated calcium ions and the smear layer removal efficiency after root canal final irrigation with three different solutions. Forty-five teeth were instrumented with rotary-files, then randomly divided into 3 equal groups (n = 15) depending on the final irrigation solution; group I: 17% ethylenediaminetetraacetic acid (EDTA), group II: 0.2% chitosan, and group III: 10% trisodium citrate. According to the time of application, every group was divided into 3 subgroups (1 min, 5 min, and 24 h). The quantification analysis of chelated calcium ions was performed by flame atomic absorption spectrometry (FAAS). Then, the presence of smear layer was examined by splitting the samples longitudinally and using scanning electron microscopy (SEM) to examine coronal, middle, and apical root canal levels. One-way analysis of variance (ANOVA) test was used for the evaluation of treatment effect. Kruskal-Wallis test was executed to detect a significant difference between groups, while Mann-Whitney U test has determined the difference between each two groups for smear layer. Both 17% EDTA and 0.2% chitosan had not been statistically significant difference for smear layer removal efficiency and observed calcium ion concentrations. Although, they were more efficient of 10% trisodium citrate with a significant difference (P < 0.05). The application time of the chelators' solutions must not exceed 5 min to completely remove smear layer, and 0.2% chitosan is a natural substitute for 17% EDTA with a safety application for 24 h.

Selective leaching of lead from lead smelter residues using EDTA.

Ethylenediaminetetraacetic acid (EDTA) has been widely used as an effective reagent for removal of lead from soil because of its high lead extraction efficiency caused by the high thermodynamic stability of the Pb(ii)–EDTA complex. In this study, EDTA was used as a lixiviant for recovery of lead from residues (matte and slag) of secondary lead smelter plants. The residues were composed mainly of iron (34–66 wt%) and lead (7–11 wt%). Leaching parameters (EDTA concentration, pH, temperature, liquid-to-solid ratio and leaching time) were optimized. The optimum leaching efficiency was achieved when leached for 1 h at room temperature using 0.05 mol L−1 EDTA at a liquid-to-solid ratio of 5 mL g−1. At such conditions, 72 to 80% of lead and less than 1% of iron were leached from both matte and slag. The high selectivity towards lead with minimal co-dissolution of iron is a major advantage since it reduces the chemical consumption and simplifies the downstream processes. Although the stability constants of the complexes Fe(iii)–EDTA, Fe(ii)–EDTA and Pb–EDTA are all large (log KS 25.1, 14.33 and 18.04, respectively), the leaching of iron was most likely limited by its presence in insoluble phases such as iron oxides, sulfides and silicates in the residues. 100% leaching of lead was achieved by a multi-step leaching process where the leaching residues were contacted three times by a fresh EDTA solution. To recover EDTA, first iron was precipitated as iron hydroxide by raising the pH of pregnant leach solution (PLS) above 12.6 using sodium hydroxide, followed by precipitation of lead as lead sulfide by adding ammonium sulfide. The recovered EDTA was successfully reused two times for leaching without significant changes in leaching yields.

Kavite tasarımının kalsiyum hidroksitin kök kanal düzensizliklerinden uzaklaştırılmasına etkisi

Objective: Conservative endodontic cavity (CEC) design has recently developed to maintain the stability of tooth and provided an alternative to traditional endodontic cavity (TEC) design. The purpose of this study was to assess the influence of cavity design on calcium hydroxide (Ca(OH)2) removal from artificial grooves in the coronal and apical parts of root canals. Materials and Methods: Fourty extracted human mandibular premolars with single canals were randomly assigned to CEC or TEC groups (n=20). Following cavity preparation, the root canals were instrumented and then, each tooth was sectioned longitudinally. Two standardized grooves were prepared in the coronal and apical parts of 1 root half. Ca(OH)2 was placed into the grooves and the root halves reassembled. After 1 week, each root canal was enlarged to a final apical size of 40 and irrigation was performed with the sonic activation of 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid solutions. The remaining Ca(OH)2 in the grooves was evaluated using a stereomicroscope and the images were scored by 2 examiners. Data were analyzed using the Mann-Whitney U and Wilcoxon tests. Ca(OH)2 remnants were found in both groups. Results: There was no significant difference between the CEC and TEC groups in terms of Ca(OH)2 removal efficacy (p&amp;gt;0.05). The grooves in the coronal and apical parts of the roots presented similar amount of Ca(OH)2 remnantsin both groups (p&amp;gt;0.05). Conclusion: The cavity design had no effect on the removal of Ca(OH)2 from root canal irregularities.

Investigating gene expression profiles of whole blood and peripheral blood mononuclear cells using multiple collection and processing methods.

Gene expression profiling using blood samples is a valuable tool for biomarker discovery in clinical studies. Different whole blood RNA collection and processing methods are highly variable and might confound comparisons of results across studies. The main aim of the current study is to compare how blood storage, extraction methodologies, and the blood components themselves may influence gene expression profiling. Whole blood and peripheral blood mononuclear cell (PBMC) samples were collected in triplicate from five healthy donors. Whole blood was collected in RNAgard® and PAXgene® Blood RNA Tubes, as well as in collection tubes with anticoagulants such as dipotassium ethylenediaminetetraacetic acid (K2EDTA) and Acid Citrate Dextrose Solution A (ACD-A). PBMCs were separated using sodium citrate Cell Preparation Tubes (CPT™), FICOLL™, magnetic separation, and the LeukoLOCK™ methods. After blood collection, the LeukoLOCK™, K2EDTA and ACD-A blood tubes were shipped overnight using cold conditions and samples from the rest of the collection were immediately frozen with or without pre-processing. The RNA was isolated from whole blood and PBMCs using a total of 10 different experimental conditions employing several widely utilized RNA isolation methods. The RNA quality was assessed by RNA Integrity Number (RIN), which showed that all PBMC procedures had the highest RIN values when blood was stabilized in TRIzol® Reagent before RNA extraction. Initial data analysis showed that human blood stored and shipped at 4°C overnight performed equally well when checked for quality using RNA integrity number when compared to frozen stabilized blood. Comparisons within and across donor/method replicates showed signal-to-noise patterns which were not captured by RIN value alone. Pathway analysis using the top 1000 false discovery rate (FDR) corrected differentially expressed genes (DEGs) showed frozen vs. cold shipping conditions greatly impacted gene expression patterns in whole blood. However, the top 1000 FDR corrected DEGs from PBMCs preserved after frozen vs. cold shipping conditions (LeukoLOCK™ preserved in RNAlater®) revealed no significantly affected pathways. Our results provide novel insight into how RNA isolation, various storage, handling, and processing methodologies can influence RNA quality and apparent gene expression using blood samples. Careful consideration is necessary to avoid bias resulting from downstream processing. Better characterization of the effects of collection method idiosyncrasies will facilitate further research in understanding the effect of gene expression variability in human sample types.

Microfluidic Approach to Generate a Tadpole-Egg-Shaped Alginate Fiber and Its Application in Tissue Engineering.

Herein, we introduce a facile microfluidic technique to produce a hybrid alginate fiber with a tadpole-egg shape. A triple-flow polydimethylsiloxane microfluidic device was constructed to allow the formation of oil droplets inside the alginate stream and was instantaneously gelated with the coaxially adjacent CaCl2. The fiber entrapping the uniform oil droplets was dehydrated, leading to the formation of a distinct tadpole-egg-shaped structure. A series of diverse fiber architectures was fabricated in a controlled manner based on the flow rates of the relevant flows. The tadpole-egg-shaped alginate fibers were employed as building blocks to create a three-dimensional microwell template for cell cultures. First, the tadpole-egg-shaped alginate fibers containing the oil droplets were half-dipped into a melted agarose solution. After the solidification of the agarose gel, the alginate fibers were degraded by an ethylenediaminetetraacetic acid (EDTA) solution to generate the hemispherical microwells. Mesenchymal stem cells (MSCs) were cultured in the microwells to generate spheroids, which were induced into chondrocytes using transforming growth factor-β3. The formed MSC spheroids exhibited a relatively high ratio of cell viability with more than 95% live cells after 14 days of culture. The success of the chondrogenic differentiation was proven based on staining (Safranin O) and the glycosaminoglycan levels. The latter was significantly higher in spheroids that were induced to form chondrocytes compared to those that were not induced after 21 days of differentiation. Second, we investigated the potential of the tadpole-egg-shaped alginate fibers as microcarriers for applications in drug delivery and implantable technologies. It was revealed that the degradation of the Ca-alginate wall of the hybrid fibers to release the oil droplets required an EDTA solution with a concentration of 500 mM for a 15 min period. This result can be used to further develop the tadpole-egg-shaped alginate fibers as uniform microcarriers with multiple compartments.

Further studies on the signal enhancement effect in laser diode thermal desorption-triple quadrupole mass spectrometry using microwell surface coatings.

The laser diode thermal desorption (LDTD) ionization source allows ultrafast and sensitive analysis of small molecules by mass spectrometry. Signal enhancement in LDTD has been observed when coating the surface of sample microwells with a solution of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid. Here we present a quantitative analysis of signal enhancement using solutions of diverse commercial proteins (lysozyme, immunoglobulin G, albumin, and fibrinogen) as coatings. Results showed that compounds with polar chemical functions such as carboxylic acid, sulfonyl, and nitro had signal enhancement factors, in most cases higher than 10, when using any of the tested proteins as coating agent. Analysis of variance revealed that immunoglobulin G and fibrinogen gave the best results. However, the signal enhancement factors obtained with these proteins were not superior to those observed with EDTA. To explain the signal enhancement effect of proteins, analysis by scanning electron microscopy of dried samples on the microwell sample plates was carried out. Images showed that salicylic acid, one of the compounds with the highest observed signal enhancement, formed a thick layer when applied directly on the uncoated surface, but it formed small crystals (<1μm) in the presence of protein or EDTA coatings. Further crystallographic studies using powder X-ray diffraction showed that the crystalline form of salicylic acid is modified in the presence of EDTA. Salicylic acid when mixed with EDTA had a higher percentage of amorphous phase (38.1%) than without EDTA (23.1%). These results appear to confirm that the diminution of crystal size of analytes and the increase of amorphous phase are implicated in signal enhancement effect observed in LDTD using microwell surface coatings. To design better coatings and completely elucidate the signal enhancement effect in LDTD, more studies are necessary to understand the effects of coatings on the ionization of analytes.

Influence of different irrigation protocols on microhardness and flexural strength values of young and aged crown dentin.

To investigate the effect of different irrigation protocols on microhardness (MH) and flexural strength (FS) values of young and aged crown dentin. In addition to ageing, root canal irrigation might also affect the mechanical properties of coronal dentin walls. One hundred and twenty dentin bars (2mm×2mm×8mm) were obtained from the crowns of extracted, non-caries, human molars of young and older patients (n=60 bars; average patient ages: 16.7 and 65.4, respectively). Subgroups were formed as follows: 2.5%NaOCl(sodium hypochlorite)+5%EDTA(ethylenediaminetetraacetic acid), 2.5%NaOCl+15%EDTA, 2.5%NaOCl, 5%EDTA, 15%EDTA and Saline. NaOCl and saline were used for 20minutes and EDTA solutions for 1minute. MH values of each sample were measured before and after the irrigation protocols. The same samples were also submitted for FS analysis. The data were statistically analysed. Young samples had lower MH values at pre- and post-treatment compared to aged samples (P<.05). A significant decrease was observed in MH values of aged samples exposed to 2.5%NaOCl and both NaOCl+EDTA combinations (P<.05). FS values of the young saline-treated group were statistically higher than aged ones (P<.05). Both NaOCl+EDTA combinations caused a significant decrease in FS values of young samples compared to saline (P<.05). Ageing has a significant effect on the MH and FS values of crown dentin samples. 5% EDTA solutions revealed similar results to 15%EDTA regarding MH and FS values of crown dentin in both age groups. The NaOCl+EDTA combination had a prominent effect than EDTA alone, on MH values of young-, and FS values of aged dentin samples.

Enhanced dielectric performance of BaxSr(1-x)TiO3 films prepared by the direct current micro-arc oxidation in the presence of ethylenediamine tetraacetic acid

BaxSr(1-x)TiO3 (BST) thin-films are fabricated on a Ti-substrate by micro-arc oxidation method in the presence of an aqueous solution of ethylenediamine tetraacetic acid (EDTA) and effects of EDTA, as additive, are investigated on the micro-structure and dielectric properties of BST thin-films. The obtained results show that EDTA delays the micro-arc oxidation reaction and results in a controllable slow-growth of the thin-film. Although, a remarkable thin film is obtained, however, capacitance of the prepared film is prominently increased. When concentration of EDTA is 0.05 M, the best compactness and smoothness for the film are observed. Moreover, the largest dielectric constant and smallest dielectric-loss are attained. In addition, the largest residual polarization strength (2Pr) of 3.4 μC/cm2 is also attained under this condition.

Hydrogen-Bonded Multilayer Thin Films and Capsules Based on Poly(2-n-propyl-2-oxazoline) and Tannic Acid: Investigation on Intermolecular Forces, Stability, and Permeability.

In recent years, hydrogen-bonded multilayer thin films and capsules based on neutral and nontoxic building blocks have been receiving interest for the design of stimuli-responsive drug delivery systems and for the preparation of thin-film coatings. Capsule systems made of tannic acid (TA), a natural polyphenol, as a hydrogen bonding donor and poly(2-n-propyl-2-oxazoline) (PnPropOx), a polymer with lower critical solution temperature around 25 °C, as a hydrogen bonding acceptor are advantageous over other conventional hydrogen-bonded systems because of their high stability in physiological pH range, biocompatibility, good renal clearance, stealth behavior, and stimuli responsiveness for temperature and pH. In this work, investigations on the interactive forces in TA/PnPropOx capsule formation, film thickness, stability, and permeability are reported. The multilayer thin films were assembled on quartz substrates, and the layer-by-layer film growth was investigated by UV-vis spectroscopy, atomic force microscopy, and profilometry. Hollow capsules were fabricated by sequential coating of TA and PnPropOx onto CaCO3 colloidal particles, followed by template dissolution with a 0.2 M ethylenediaminetetraacetic acid solution. The obtained capsules and multilayer thin films were found to be stable over a wide pH range of 2-9. It is found that both hydrogen bonding and hydrophobic interactions are responsible for the enhanced stability of the capsules at higher pH range. Swelling followed by dissolution of the capsules was observed at a pH value lower than 2, while the capsules undergo shrinking at a pH value higher than 8 and finally transform into a particle-like morphology before dissolution. The TA/PnPropOx capsules reported here could be used as a temperature-responsive drug delivery system in controlled drug delivery applications.

Glycolic acid: Characterization of a new final irrigant and effects on flexural strength and structural integrity of dentin

The aim of this study was to characterize glycolic acid (GA) and examine its effects on powder and flexural strength of dentin. Particle size and energy-dispersive EDS in GA powder was performed for chemical analysis. Surface tension and pH levels of ethylenediaminetetraacetic acid (EDTA), citric acid (CA), and GA solutions were evaluated at different times and temperatures. Dentin powder and mineralized dentin beams were immersed for 1 min in EDTA, CA, or GA solutions and subjected to Fourier transform infrared spectroscopy for apatite/collagen ratio analysis and 3-point flexure test, respectively. GA showed the largest particle size (μm), and its surface tension was similar to that of EDTA and CA. Surface tension decreased in solutions of higher concentrations. GA showed pH stability at all times and temperatures evaluated. The apatite/collagen ratio reduced with increased GA concentrations, while flexural strength was not significantly affected by GA concentration. GA seems a good choice as a final irrigation solution after root canal preparation.