The kinetic and mechanistic studies for the reaction of hydroxyl radical with two quinoline based herbicides, namely, quinclorac and quinmerac has been performed using various computational methods ...in aqueous media. Geometry optimizations were performed using Density Functional Theory (DFT) methods including water as the solvent. Local reactivity parameters of these herbicides towards the •OH radical are predicted using condensed Fukui function. Single point energies of various species were calculated using double hybrid method, namely, B2PLYP–D for better accuracy. The pKa values for these acid based herbicides allow them to exist in deprotonated form in aqueous condition. Hence, the calculations are also performed for the deprotonated or the anionic form apart from the neutral species. Individual rate coefficients for •OH radical addition reaction with each carbon atoms were evaluated using conventional transition state theory using one–dimensional tunneling corrections. The solvent effect on reaction is implemented through Collins–Kimball formulations. Both the approaches, namely, the Fukui index and individual rate constant determination confirms that the most reactive site for the •OH radical addition in these two herbicide is the carbon atom attached to the COOH group. The total rate constant for the •OH radical reaction with both neutral and anionic forms of these two herbicides are relatively high and equal to its diffusion‐limit value. Evaluation of the ecotoxicities of the parent herbicides and their OH adducts is estimated using the structure–activity relationship concept.
The advanced oxidative process (AOP) is the effective degradation process for the removal of herbicides from soil and water bodies which involves the generation of highly reactive oxidizing •OH radical. The present study involves reaction kinetics, mechanism and the degradation pathways for two herbicides, namely, quinclorac and quinmerac with •OH radical. Rate constants were determined using theoretical approach in aqueous media. Local reactivity of •OH radical with the herbicides was evaluated. Toxicity of parent and their OH adduct products was also estimated.
Obstructive sleep apnea (OSA) is highly prevalent in children and is usually treated by adenotonsillectomy. Nonsurgical therapies for OSA consist primarily of antiinflammatory approaches and have ...gained popularity, but their efficacy remains to be critically examined.
To determine the effect of montelukast on pediatric OSA.
A prospective randomized double-blind controlled trial of polysomnographically diagnosed OSA in children ages 2-10 years who were treated with either oral montelukast (4 or 5 mg daily) or placebo for 16 weeks. Adherence to the medication was ascertained using automated timed pill dispensers along with weekly telephonic reminders.
Ninety-two children diagnosed with OSA were approached, and 64 (69.6%) agreed to participate. Of these, 57 (89.0%) completed the 16-week trial, 28 in the montelukast group and 29 in the placebo group. Age, sex, and percentage of obesity were similar in the two groups, as were initial apnea-hypopnea index (AHI) scores. Overall, intention-to-treat analyses revealed that beneficial effects occurred in 20 children receiving montelukast (71.4%), whereas only 2 (6.9%) of the children receiving placebo showed reductions in AHI score (P < 0.001). Indeed, AHI decreased from 9.2 ± 4.1/hour total sleep time (TST) to 4.2 ± 2.8/hour TST (P < 0.0001) in montelukast-treated children, whereas in children receiving placebo, the AHI did not change (from 8.2 ± 5.0/h TST before to 8.7 ± 4.9/h TST at completion of the trial).
When compared with placebo, montelukast for 16 weeks effectively reduced the severity of obstructive sleep apnea in children 2-10 years of age. These results support a therapeutic role for leukotriene modifiers in pediatric OSA provided that long-term trials confirm current findings. Clinical trial registered with www.clinicaltrials.gov (NCT 00599534).
In the present work, Acid Red 1 (AR1) dye degradation by two heterogeneous Fenton catalysts, namely iron loaded rice husk biochar (Fe-RHB) and coir pith biochar (Fe-CPB) are studied. Biochar prepared ...from RHB and CPB were sonicated in the presence of ferric nitrate for the synthesis of Fe-RHB and Fe-CPB by incipient impregnation method. Effect of operational parameters such as pH, the dosage of catalyst, H2O2 concentration and temperature were examined. Characterization of the synthesized Fenton catalyst, Fe-RHB and Fe-CPB were analysed by SEM, EDS, XRD and XPS techniques. In Fe-RHB Fenton system, maximum dye removal efficiency of 97.6% and TOC removal efficiency of 84.2% were obtained at pH 3 for 50 mg L−1 of AR1 concentration, with 16 mM of H2O2 and 5 g L−1 of catalyst dosage within 120 min reaction time. Similarly, for Fe-CPB, maximum dye removal efficiency of 99.1% and TOC removal efficiency of 86.7% were obtained with 16 mM of H2O2 and 4 g L−1 of dosage for 50 mg L−1 of initial dye concentration at pH 3. The prepared catalysts can be reused for successive cycles as the catalyst materials are highly stable and have very less iron leaching property.
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•Iron impregnated biochars are effective heterogeneous Fenton catalyst.•Almost complete decolourization and >85% mineralization efficiency were observed.•Prepared catalysts are highly stable and reusable.
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The effect of leachate (L) as a reaction medium in hydrothermal carbonization (HTC) of food waste (FW) on the thermal behaviour of the resulting hydrochar (H) was investigated. The ...physicochemical and structural characterization of FW hydrochar produced using leachate (FWH-L) at different process temperatures (180/210/240 °C) confirmed the improved properties over raw FW. Kinetic analysis using Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods revealed that FWH-L have a lower activation energy (Ea) than raw FW. The average Ea values for raw FW by FWO, KAS and Friedman methods were 196.18, 196.85, 206.34 kJ/mol, respectively, while for FWH-L they were 127.89, 124.22 and 134.5 kJ/mol, respectively. The computed thermodynamic parameters showed that FWH-L has improved combustion behaviour. The results of FWH-L are well comparable to FW hydrochar produced using distilled water (FWH-DW). These findings demonstrated that residual ions in leachate would act as a catalyst, benefiting the HTC degradation reaction path.
The kinetics and mechanism in the oxidative degradation pathways of the
•
OH radical reaction with seven auxin mimic aromatic acid-based herbicides were investigated with the help of various ...theoretical methods. Various global and local reactivity parameters such as ionization energy, molecular hardness, electrophilicity, condensed Fukui function, and total energies were determined to predict the reactivity of these herbicides towards the
•
OH radical. Geometry optimization was performed at the CAM–B3LYP/6–311 + G(d) level of theory including the solvent effect using the polarizable continuum model (PCM) incorporating the integral equation formalism (IEF) with water as solvent. Single point energies of various species were calculated at ROMP2/aug–cc–pVDZ level of theory for better accuracy. The
pK
a
values for these acid-based herbicides allow them to exist in the deprotonated form in aqueous condition. Hence, the calculations are also performed for the deprotonated form apart from the neutral species. The most reactive site for the
•
OH radical reaction is predicted and validated for neutral and deprotonated species. Once the most reactive site is known, the reaction rate constants are calculated theoretically by the traditional transition–state theory using one-dimensional tunneling corrections. The solvent effect on the reaction rate constant is implemented through Collins–Kimball formulations.
Through an analysis of land use and land cover (LULC) data for the years 2005 and 2017 from the Advanced Wide Field Sensor onboard the Indian Remote Sensing satellite, we find considerable changes in ...the LULC in three major states of south India, namely, Tamil Nadu, Telangana and Kerala. This change is mainly due to increasing urbanization, in addition to the change of prevalent mixed forest into deciduous needle/leaf forest in Kerala. Motivated by this finding, we study the impact of these LULC changes over a decade on the extremes of twelve heavy rainfall events in these states through several sensitivity experiments with a convection‐permitting Weather Research and Forecasting model, by changing the LULC boundary conditions. We particularly focus on three representative heavy rainfall events, specifically, over (a) Chennai (1 December 2015), (b) Telangana (24 September 2016), and (c) Kerala (15 August 2018). The simulated rainfall patterns of the three heavy rainfall events are found to be relatively better with the use of the 2017 LULC boundary conditions. The improvement is statistically significant in the case of the Chennai and Kerala events. On analysis of these simulations, and output from additional simulations we have conducted for nine other heavy rainfall events, we suggest that the recent LULC changes result in higher surface temperatures and sensible heat fluxes, and a deeper and moist boundary layer. This causes a relatively higher convective available potential energy and, consequently, heavier rainfall. We find the LULC changes in the three states, mainly dominated by the increasing urbanization in Telangana and Tamil Nadu, enhance the rainfall during the heavy rainfall events by 20–25%. This is the first extensive investigation of multiple and multi‐regional cases over the Indian region.
We find that heavy rainfall events are increasing in three major south Indian states: Telangana, Tamil Nadu and Kerala. Increasing urbanization is contributing by 20–25% to extremes of rainfall events during the monsoon, as demonstrated through our simulation and Land Use Land Cover change sensitivity experiments for twelve events with a convection‐resolving high‐resolution regional weather model. The following figure shows, as an example, the Chennai event from three observations (top panel), and the simulations with different LULCs.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), initially originated in China in year 2019 and spread rapidly across the globe within 5 months, causing over 96 million cases of ...infection and over 2 million deaths. Huge efforts were undertaken to bring the COVID-19 vaccines in clinical development, so that it can be made available at the earliest, if found to be efficacious in the trials. We developed a candidate vaccine ZyCoV-D comprising of a DNA plasmid vector carrying the gene encoding the spike protein (S) of the SARS-CoV-2 virus. The S protein of the virus includes the receptor binding domain (RBD), responsible for binding to the human angiotensin converting enzyme (ACE-2) receptor. The DNA plasmid construct was transformed into E. coli cells for large scale production. The immunogenicity potential of the plasmid DNA has been evaluated in mice, guinea pig, and rabbit models by intradermal route at 25, 100 and 500 µg dose. Based on the animal studies proof-of-concept has been established and preclinical toxicology (PCT) studies were conducted in rat and rabbit model. Preliminary animal study demonstrates that the candidate DNA vaccine induces antibody response including neutralizing antibodies against SARS-CoV-2 and also elicited Th-1 response as evidenced by elevated IFN-γ levels.
The characterization of various intermediates in the ultrafast deactivation of photoexcited (Z,Z)-bilirubin-IXα was carried out using different computational methods. Various excited states of ...(Z,Z)-bilirubin-IXα and their respective vertical excitation energies were calculated using time-dependent density functional theory (TD-DFT) employing the Coulomb-attenuating method (CAM) combined with the B3LYP functional, which is known to predict accurate results on the charge transfer excitation process. Optimized geometries and absorption spectra were determined in chloroform solvent using the polarizable continuum model incorporating the integral equation formalism. The optimized geometries of different conformers of bilirubin (ZZ, ZE , EZ , and EE ) along with their relative energies and vertical excitation energies were obtained. The geometry of the first excited state, S1, for the ZZ conformer was optimized using TD-DFT. The computational study suggests that excited-state intramolecular proton transfer (ESIPT) plays a major role in the deactivation process of (Z,Z)-bilirubin-IXα on a shorter time scale. The lactam–lactim tautomerism that arises from the ESIPT process gives rise to various intermediates of (Z,Z)-bilirubin-IXα. The computational results nicely corroborate the experimental findings available in the literature.
In high-power traction drives using induction motors, during operation above the base speed, it is generally preferred to drive the machine in the square-wave mode since it offers maximum dc-bus ...utilization and reduced switching loss. However, the conventional field-oriented control method cannot control the drive effectively in square-wave mode since independent control of torque and flux is difficult to achieve due to stator voltage saturation. This article proposes a new technique to control the drive in the square-wave mode where only 1 DOF is available for control. In the square-wave mode, the proposed method controls the torque of the machine by directly varying the stator voltage angle with respect to the rotor flux axis. The flux of the machine is kept at a required value below the saturation limit by appropriate selection of the operating point. The proposed control strategy also offers good torque dynamics in the square-wave operating mode. The control algorithm is experimentally verified on a 5.5-kW induction machine drive and the experimental results are presented.
•Landfill leachate (LL) was used as liquid source during HTC of MSWs.•LL resulted in lower hydrochar mass yields than conventional distilled water.•LL had no adverse effect on the fuel ...characteristics of the hydrochars.•The HHV of the hydrochars is comparable to traditional solid fuels.•Use of LL as moisture source can improve the sustainability of HTC processes.
Hydrothermal carbonization (HTC) of yard waste (YW) and food waste (FW) was performed in landfill leachate (LL) to overcome the unnecessary exploitation of our limited natural resources. The physicochemical properties and combustion behavior of the resulting hydrochars were compared with those obtained using distilled water (DW) as reaction medium. Although performing HTC in LL led to lower hydrochar mass yields (43% YWH and 36% FWH) than DW (47.1% YWH and 41.5% FWH), it had minimal impact on the fuel characteristics of the hydrochars. Notably, the higher heating value of the hydrochars prepared in LL (22.8 MJ kg−1 for YWH and 30.2 MJ kg−1 for FWH) is comparable to that of conventional solid fuels, and may, therefore, be considered as inexpensive alternatives to fossil fuels. Overall, the results of this study conclusively suggest that the use of LL as an alternative moisture source can significantly improve the sustainability of HTC technology.
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