Refit to numerically problematic UMIST reaction rate coefficients

Aims. Chemical databases such as the UMIST Database for Astrochemistry (UDFA) are indispensable in the numerical modeling of astrochemical networks. Several of the listed reactions in the UDFA have properties that are problematic in numerical computations: Some are parametrized in a way that leads to extremely divergent behavior for low kinetic temperatures. Other reactions possess multiple entries that are each valid in a different temperature regime, but have no smooth transition when switching from one to another. Numerically, this introduces many difficulties.We present corrected parametrizations for these sets of reactions in the UDFA06 database. Methods. From the tabulated parametrization in UDFA, we created artificial data points and used a Levenberg-Marquardt algorithm to find a set of improved fit parameters without divergent behavior for low temperatures. For reactions with multiple entries in the database that each possess a different temperature regime, we present one joint parametrization that is designed to be valid over the whole cumulative temperature range of all individual reactions. Results. We show that it is possible to parametrize numerically problematic reactions from UDFA in a form that avoids low temperature divergence. Additionally, we demonstrate that it is possible to give a collective parametrization for reaction rate coefficients of reactions with multiple entries in UDFA. We present these new fitted values in tabulated form.Comment: accepted by A&

The Effect of Organic Loading on Propylene Glycol Removal Using Fixed Bed Activated Sludge Hybrid Reactor

Propylene glycol is discharged to the surface and underground waters and vicinity soils via industrial wastewater effluents, posing many health and environmental risks. The main goal of this study was to remove propylene glycol from synthetic wastewater in a fixed bed activated sludge reactor. To observe the effects of organic loading on bioreactor performance, the organic loading was increased by two sequencing stages: first by hydraulic retention time (HRT) depletion and second via propylene glycol concentration increase. Propylene glycol removal efficiency in HRTs of 8, 6, 4 and 2 h was 95.86, 95.12, 93.96 and 79.08 % respectively. A constant HRT of 6 h was selected for the second stage; propylene glycol concentrations of 500, 1000, 1500, 2000 and 2500 mg L–1 were used. The removal efficiency for these concentrations was 95.12, 95.95, 88.54, 75.95 and 35.69 % respectively. Thus, the integrated fixed bed activated sludge reactor is an efficient, viable and promising technology for treating wastewaters containing propylene glycol

Removal of Estrogen Hormones (17-Estradiol and Estrone) from Aqueous Solutions Using Rice Husk Silica

The aim of this study was to investigate the removal of estrogen hormones (17β-estradiol and estrone) from aqueous solutions using rice husk extracted silica. Rice husk was collected from rice factories in Mazandaran province (Iran) and the adsorbent was prepared in a furnace at 800 °C for 4 h, after acid leaching with hydrochloric and sulfuric acid mixture. Optimal operating parameters for estrogen removal were determined, including initial pH values (4–9), adsorbent dosages (0.5, 1, 1.5, and 2 g L–1), contact times (30, 60, 90, and 120 min), and initial concentrations of 17β-estradiol and estrone (10, 40, 70 and 100 ng L–1); one-factor-at-a-time method was used. The method of electrochemiluminescence was used to measure the concentration of hormones. Kinetic adsorption models and adsorption isotherms were also studied. The maximum removal efficiency (%) of 17β-estradiol (E2) and estrone (E1) hormones of 95.5 and 93.1 %, respectively, was obtained at optimal conditions of pH 4, 1.5 g L–1 of adsorbent dosage, 60 min of contact time and 10 ng L–1 initial concentrations of E2 and E1. Pseudo first-order kinetic model and Langmuir adsorption isotherm had the best fit with experimental data for both estrogen hormones, following nonlinear regression procedure. Rice husk silica could be considered as effective and accessible adsorbent for removal of estrogenic hormones. This work is licensed under a Creative Commons Attribution 4.0 International License

A Novel Integration of CWPO Process with Fe3O4@C and Sonication for Oxidative Degradation of 4-Chlorophenol

This current work deals with oxidative destruction of 4-chlorophenol (4-CP) with catalytic wet peroxide oxidation (CWPO) using Fe3O4@C and sonication (US) in aqueous solution. The Fe3O4@C catalyst was synthetized and characterized with Field Emission Electron Microscopy and X-Ray Diffraction. Effect of operational variables, including initial pH, catalyst dosage, H2O2 concentration, 4-CP concentration, and sonication were investigated. A removal efficiency of 99 % was obtained by the CWPO/US-Fe3O4@C process in selected conditions including pH 5, Fe3O4@C dosage of 0.8 g L–1, H2O2 concentration of 20 mM, sonication power of 300 W, and reaction time of 60 min. Results indicated significant 4-CP removal with CWPO/US-Fe3O4@C (99 %) compared to CWPO (67 %) and US (10 %). According to the results, Fe3O4@C nanocomposite can be considered a cost-effective catalyst since it demonstrated acceptable reusability performance in degradation of 4-CP by CWPO/US-Fe3O4@C process. This work is licensed under a Creative Commons Attribution 4.0 International License

Plasma mEV levels in Ghanain malaria patients with low parasitaemia are higher than those of healthy controls, raising the potential for parasite markers in mEVs as diagnostic targets

This study sought to measure medium-sized extracellular vesicles (mEVs) in plasma, when patients have low Plasmodium falciparum early in infection. We aimed to define the relationship between plasma mEVs and: (i) parasitaemia, (ii) period from onset of malaria symptoms until seeking medical care (patient delay, PD), (iii) age and (iv) gender. In this cross-sectional study, n = 434 patients were analysed and Nanosight Tracking Analysis (NTA) used to quantify mEVs (vesicles of 150–500 nm diameter, isolated at 15,000 × g, β-tubulin-positive and staining for annexin V, but weak or negative for CD81). Overall plasma mEV levels (1.69 × 1010 mEVs mL−1) were 2.3-fold higher than for uninfected controls (0.51 × 1010 mEVs mL−1). Divided into four age groups, we found a bimodal distribution with 2.5- and 2.1-fold higher mEVs in infected children (10 mEVs mL−1) and the elderly (>45 yo) (median:1.92 × 1010 mEVs mL−1), respectively, compared to uninfected controls; parasite density varied similarly with age groups. There was a positive association between mEVs and parasite density (r = 0.587, p p p = 0.667). Parasite density was also exponentially related to patient delay. Gender (p = 0.667) had no effect on plasma mEV levels. During periods of low parasitaemia (PD = 72h), mEVs were 0.93-fold greater than in uninfected controls. As 75% (49/65) of patients had low parasitaemia levels (20–500 parasites µL−1), close to the detection limits of microscopy of Giemsa-stained thick blood films (5–150 parasites µL−1), mEV quantification by NTA could potentially have early diagnostic value, and raises the potential of Pf markers in mEVs as early diagnostic targets

Powder activated carbon/Fe3O4 hybrid composite as a highly efficient heterogeneous catalyst for Fenton oxidation of tetracycline: Degradation mechanism and kinetic

In this work, we prepared and used a composite of powder activate carbon/Fe3O4 magnetic nanoparticles (PAC/Fe3O4 MNPs) as a heterogeneous catalyst to remove tetracycline (TC) from aqueous solution. By using XRD, BET, VSM, SEM, TEM and EDX techniques, also, we tried to characterize the catalyst. The effects of pH, H2O2, catalyst dosages and also initial TC concentration on the degradation process were assessed. Based on the results, it was indicated that at low pH values and initial TC concentrations, the efficiency of the process is higher than the other values and concentrations studied in this work. Under the ambient conditions and setting the initial pH value and TC concentration at respectively 3.0 ± 0.2 and 10 mg L-1, the optimal dosage of reagents were recorded to be 0.3 g L-1 catalyst and 80.0 mM H2O2. The values of observed rate constants, kobs, increased by increasing the catalyst loading in the system; however, these values decreases when the initial TC concentration was increased. Our findings indicated that all of TC concentration was nearly degraded during the 180 min reaction. Regarding the reusability of PAC/Fe3O4 MNPs, the results showed that TC and TOC removal efficiencies of 94.5 and 32.3, respectively, can be achieved after four consecutive runs. By conducting the stability experiments, it was confirmed that PAC/Fe3O4 MNPs is a promising and effective catalyst in Fenton reactions and can be used to treat TC-contaminated water with very low loss of catalytic activity. © 2015 The Royal Society of Chemistry

Electrocardiographic patterns in biventricular pacing delivered by second-generation cardiac resynchronization devices

Background: With increasing use of cardiac resynchronization therapy (CRT), treating physicians should be familiar with different electrocardiographic (ECG) patterns of left ventricular (LV) lead and biventricular (BiV) pacing. However, there are a few publications on ECG patterns during BiV pacing. Purpose: This study was sought to determine different ECG patterns in patients with BiV pacing. Methods: Twelve-lead ECGs during BiV pacing (right ventricular leads at apex and LV leads in one of the lateral coronary veins) were analyzed in 181 consecutive patients (121 male; mean age, 62.0 ± 13.5 years) with advanced heart failure and baseline left bundle branch block pattern after at least 6-month of uncomplicated CRT. Results: During BiV pacing, 65 of the patients showed a dominant R wave in V1. There was a right axis deviation in 57 in frontal plane. However, a left superior axis emerged in 34 and normal frontal plane axis in 9. Sequential BiV pacing (73 vs. 58, P = 0.04) and pacing from posterolateral coronary vein (80 vs. 60, p = 0.045) were more likely to present with a dominant R wave in V1. In sequential pacing, AV interval was significantly longer in patients with negative complex in V1 than in those with positive complex (124 ± 21 vs. 116 ± 8.0, p = 0.005). A Q/q wave was detected in 85 of patients in lead I and 78 in lead aVL. Conclusions: BiV pacing from lateral coronary venous branches and right ventricular apex characteristically presented with dominant R wave in V1, Q/q wave in leads I and aVL, and right or left superior axis. However, a negative complex in V1, QRS axis in other quadrants, and lack of Q/q wave in leads I and aVL did not necessarily indicate a problem. © 2017 Indian Heart Rhythm Societ

Effectiveness of biostimulation through nutrient content on the bioremediation of phenanthrene contaminated soil

Bioremediation has shown its applicability for removal of polycyclic aromatic hydrocarbons (PAHs) from soil and sediments. In the present study, the effect of biostimulation on phenanthrene removal from contaminated soil via adding macro and/or micronutrients and trace elements was investigated. For these purposes three macro nutrients (as N, P and K), eight micronutrients (as Mg, S, Fe, Cl, Zn, Mn, Cu and Na) and four trace elements (as B, Mo, Co and Ni) in 11 mineral salts (MS) as variables were used. Placket-Burman statistical design was used to evaluate significance of variables (MS) in two levels of high and low. A consortium of adapted microorganisms with PAHs was used for inoculation to the soil slurry which was spiked with phenanthrene in concentration of 500 mg/kg soil. The optimal reduction resulted when a high level of macro nutrient in the range of 67-87 and low level of micro nutrient in the range of 12-32 were used with the nitrogen as the dominant macronutrient. The Pareto chart showed that NH4NO3 was the most effective variable in this experiment. The effect of elements on phenanthrene biodegradation showed following sequence as N > K > P > Cl > Na > Mg. Effectiveness of the other elements in all runs was less than 1. The type and concentration of nutrient can play an important role in biodegradation of phenanthrene. Biostimulation with suitable combination of nutrient can enhance bioremediation of PAHs contaminated soils. ©2014 Kalantary et al

Visible Light Photocatalytic Degradation of Azo Dye and a Real Textile Wastewater Using Mn, Mo, La/TiO2/AC Nanocomposite

Mn, Mo, La/TiO2/activated carbon (AC) photocatalysts were synthesized by sol-gel method. The prepared samples were characterized by XRD, FT-IR, BET, DRS, and FESEM techniques. The findings revealed that the synthesized catalysts were anatase type and nano-sized particles. The catalysts exhibited high adsorption ability in the visible light region with a red shift in the adsorption edge. The formation of Mn, Mo, La/TiO2/ AC crystallites in the activated carbon was confirmed by FE-SEM. The effects of initial dye concentration, catalyst dosage, reaction time, and solution pH were investigated for removal of Reactive Red 198. According to the obtained results, the maximum removal efficiency of 91 % was obtained at initial dye concentration of 20 mg L–1, pH of 3, and catalyst concentration of 2 g L–1. Synthesized nano-photocatalyst showed reasonable photo degradation efficiency of 84 % for initial COD concentration of 4700 mg L–1 in treatment of a real textile wastewater sample. GC/MS analysis of raw and treated wastewater confirmed degradation and producing of simple intermediates during the photocatalytic process. This work is licensed under a Creative Commons Attribution 4.0 International License