Decontamination of arsenic(V)-contained liquid phase utilizing Fe3O4/bone char nanocomposite encapsulated in chitosan biopolymer

The application of a novel nanocomposite synthesized through the combination of Fe₃O₄ nanoparticles and bone char particles for the adsorption of As(V) ions in the aquatic medium was investigated. As-prepared nanocomposite was immobilized by using chitosan biopolymer. The characterization of the nanocomposite was performed via SEM, XRD, FT-IR, and BET together with the determination of zero-point charge of the adsorbent surface. As results, the obtained experimental data were fitted well with pseudo-first-order kinetic model (R² = 0.997) and Langmuir isotherm model (R² = 0.990) with the maximum adsorption capacity of about 112 μg/g. Increasing the dosage of nanocomposite and initial solute concentration led to increasing the adsorption capacity of As(V) ions, while decreasing the solution temperature resulted in the enhanced adsorption process. According to the results of thermodynamic study, the adsorption of As(V) ions onto the nanocomposite was spontaneous and exothermic in nature.

Sono-assisted adsorption of a textile dye on milk vetch-derived charcoal supported by silica nanopowder

This study was performed to assess the efficiency of silica nanopowder (SNP)/milk vetch-derived charcoal (MVDC) nanocomposite coupled with the ultrasonic irradiation named sono-adsorption process for treating water-contained Basic Red 46 (BR46) dye. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR) were performed for the characterization of as-prepared adsorbent. The sono-assisted adsorption process was optimized using response surface optimization on the basis of central composite design by the application of quadratic model. Accordingly, the color removal can be retained more than 93% by an initial BR46 concentration of 8 mg/L, sonication time of 31 min, adsorbent dosage of 1.2 g/L and initial pH of 9. The pseudo-second order kinetic model described the sono-assisted adsorption of BR46 reasonably well (R² > 0.99). The intra-particular diffusion kinetic model pointed out that the sono-assisted adsorption of BR46 onto SNP/MVDC nanocomposite was diffusion controlled as well as that ultrasonication enhanced the diffusion rate.

Enhanced sonocatalysis of textile wastewater using bentonite-supported ZnO nanoparticles: Response surface methodological approach

The scope of this study was the use of bentonite as the carrier of ZnO nanoparticles for enhancing the sonocatalytic decolorization of Basic Red 46 (BR46) in the aqueous phase. The results demonstrated the higher sonocatalytic activity of bentonite-supported ZnO nanoparticles (BSZNs) in comparison with the suspended ZnO nanoparticles (SZNs). The particle size of BSZNs (5-40 nm) was lower than that of SZNs (20-120 nm). Due to the immobilization of ZnO nanoparticles, a specific surface area of 80.6 m(2)/g was obtained for the BSZNs, which was higher than the specific surface area of the raw bentonite (42.2 m(2)/g). Optimization of the process via response surface methodology (RSM) based on central composite design (CCD) showed the maximum sonocatalytic decolorization efficiency (%) of 89.92% in which the initial dye concentration, the ZnO/bentonite ratio, the sonocatalyst dosage, and the initial pH were 6 mg/L, 0.3, 2.5 g/L and 9, respectively. The byproducts generated during the sonocatalysis of BR46 over BSZNs were identified using gas chromatography-mass spectrometry (GC-MS) analysis. From an application viewpoint, the sonocatalysis of real textile wastewater resulted in a COD removal efficiency (%) of about 44% within a reaction time of 150 min.

Periodate-assisted pulsed sonocatalysis of real textile wastewater in the presence of MgO nanoparticles: Response surface methodological optimization

The improvement of sonocatalytic treatment of real textile wastewater in the presence of MgO nanoparticles was the main goal of the present study. According to our preliminary results, the application of pulse mode of sonication, together with the addition of periodate ions, produced the greatest sonocatalytic activity and consequently, the highest chemical oxygen demand (COD) removal efficiency (73.95%) among all the assessed options. In the following, pulsed sonocatalysis of real textile wastewater in the presence of periodate ions was evaluated response surface methodologically on the basis of central composite design. Accordingly, a high correlation coefficient of 0.95 was attained for the applied statistical strategy to optimize the process. As results, a pulsed sonication time of 141min, MgO dosage of 2.4g/L, solution temperature of 314K and periodate concentration of 0.11M gave the maximum COD removal of about 85%. Under aforementioned operational conditions, the removal of total organic carbon (TOC) was obtained to be 63.34% with the reaction rate constant of 7.1×10(-3)min(-1) based on the pseudo-first order kinetic model (R(2)=0.99). Overall, periodate-assisted pulsed sonocatalysis over MgO nanoparticles can be applied as an efficient alternative process for treating and mineralizing real textile wastewater with good reusability potential.

Transport Properties of Polysulfide Species in Lithium-Sulfur Battery Electrolytes: Coupling of Experiment and Theory

A comprehensive experimental and theoretical analysis of the isothermal transport of species for the two model ternary-electrolytes with LiTFSI-Li2S4/dioxolane (DOL)-dimethoxyethane (DME) and LiTFSI-Li2S6/DOL-DME formulations is presented. An unambiguous picture of the polysulfide's mobility is set forth after a detailed investigation of the macroscopic transference number and diffusion coefficients. The new findings of incongruent diffusion for Li2S4 species and high significance of cross-term diffusion coefficients reformulate a fledgling view of the prevalent redox-shuttle phenomena. The practical implications of this complex mechanism are discussed in detail.

Sonocatalyzed decolorization of synthetic textile wastewater using sonochemically synthesized MgO nanostructures

The present study focused on the synthesis of nanostructured MgO via sonochemical method and its application as sonocatalyst for the decolorization of Basic Red 46 (BR46) dye under ultrasonic irradiation. The sonocatalyst was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray microanalysis (EDX). In the following, the sonocatalytic removal of the dye under different operational conditions was evaluated kinetically on the basis of pseudo first-order kinetic model. The reaction rate of sonocatalyzed decolorization using MgO nanostructures (12.7 × 10(-3) min(-1)) was more efficient than that of ultrasound alone (2.0 × 10(-3) min(-1)). The increased sonocatalyst dosage showed better sonocatalytic activity but the application of excessive dosage should be avoided. The presence of periodate ions substantially increased the decolorization rate from 14.76 × 10(-3) to 33.4 × 10(-3) min(-1). Although the application of aeration favored the decolorization rate (17.8 × 10(-3) min(-1)), the addition of hydrogen peroxide resulted in a considerable decrease in the decolorization rate (9.5 × 10(-3) min(-1)) due to its scavenging effects at specific concentrations. Unlike alcoholic compounds, the addition of phenol had an insignificant scavenging effect on the sonocatalysis. A mineralization rate of 7.4 × 10(-3) min(-1) was obtained within 120 min. The intermediate byproducts were also detected using GC-MS analysis.

Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation

In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

Bioelectrochemical denitrification using carbon felt/multiwall carbon nanotube

The aim of this work was to enhance the efficiency of a bioelectrochemical denitrification process using a biocathode of carbon felt (CF)/multiwall carbon nanotube (MWCNT) composite. The efficiency of the bioelectrochemical denitrification was assessed as the function of various operational parameters, such as ORP, pH, current density, retention time and nitrate concentrations. Scanning electron microscope (SEM) images of the biocathode surfaces revealed a homogeneous distribution of the MWCNT on the CF matrix. Optimum ORP, pH, current density and retention time were -100 mV, 7.0, 15 mA/cm2 and 6 h, respectively. The highest nitrate removal efficiency at the optimum condition was 92.7% for CF/MWCNT. The reduction time for achieving the nitrate standard using CF/MWCNT was 4 h. It is proposed that the prepared nanocomposite will have the best biocathode properties in the bioelectrochemistry denitrification experiments.

Kinetics of Oxygen Reduction in Aprotic Li-O2 Cells: A Model-Based Study

A comprehensive and general kinetic model is developed for the oxygen reduction reaction in aprotic Li-O2 cells. The model is based on the competitive uptake of lithium superoxide by the surface and solution. A demonstrative kinetic study is provided to demystify the origin of curvature in Tafel plots as well as the current dependency and aberrant diversity of the nature and morphology of discharge products in these systems. Our results are general and extend to any system where solubilization of superoxide is favored, such as where phase-transfer catalysts play an important role.

In-vitro comparison of instrumentation time and cleaning capacity between endodontic handpiece and manual preparation techniques in primary molar teeth

AIM

The aim of this study was to evaluate and compare the cleaning ability and instrumentation time of manual method and use of endodontic handpiece for preparation of primary molar teeth.

METHODS

Forty primary teeth canals were used in this experimental study. Access cavities were prepared and India ink was injected into the canals. The samples were divided into three groups according to the preparation technique. In the first group the root canals were manually instrumented by k_files. Endodontic handpiece (TEP-ER10, NSK, Japan) were used for canal preparation in the second group and the samples in the third group (control) were not instrumented. After preparing the canal, the teeth were cleared with methyl salicylate and the removal of India ink was measured in the cervical, middle and apical thirds. The instrumentation time was transcribed by chronometer. Statistical analysis was performed using Mann-Whitney and t-test.

RESULTS

There was no significant difference in cleaning capacity between the two techniques, but results of the first and second group differ from those of the control group. In fact, time taken for preparation was significantly shorter with endodontic handpiece system.

CONCLUSION

Seen the shorter working time of endodontic handpiece and the similar cleaning ability of the two techniques, the application of the endodontic handpiece is recommended for preparation of deciduous root canals during pulpectomy.

The effect of participatory community-based diabetes cares on the control of diabetes and its risk factors in western suburb of Yasouj, Iran

This study aimed to investigate whether a community-based participatory diabetes care program could efficiently improve diabetic care and reduce its risk factors. To induce a participatory approach, a local group was established in partnership with academics, local leaders, health providers and public representatives. The group conducted community needs assessment and priority setting process. Diabetes was identified as the first priority health problem in this area. A total of 2569 30- to 65-year-old residents were screened for diabetes and 405 of them took part in a 13-week nutrition education and physical exercise intervention. Out of 1336 high-risk individuals, 17% had fasting blood sugar (FBS) ≥126 mg/dl and 13.5% with FBS between 110 and 125 mg/dl. Percentages of participants with triglycerides (TG) ≥150 mg/dl and cholesterol ≥200 mg/dl were 33.8% and 23.5%, respectively. After completion of the intervention, the mean FBS, HbA1C, TG and cholesterol were decreased significantly. Although systolic and diastolic blood pressure and body mass index were decreased too, the differences were not statistically significant. The mean physical activity increased and consumption of fried foods and saturated oil decreased significantly. The results suggest that participatory community-based care could be a feasible model for control of diabetes and its risk factors.

Stem cells therapy for retinal degeneration

Stem cell therapy is widely considered as a therapeutic approach for retinal degeneration. Retinal injury results in permanent visual disturbance or blindness. Repair of such damage by stem cells is one of the most feasible types of central nervous system repair. In this review, we consider how stem cells might be optimized for use as donor cells. We discuss the benefits of stem cells for transplantation in retinal degenerative disease. A wide range of stem cells from different sources is being investigated for the treatment of retinal degeneration. This study reviews the recent and old achievements about stem cells for retinal repair.