Role of Hydrogen Abstraction Acetylene Addition Mechanisms in the Formation of Chlorinated Naphthalenes. 2. Kinetic Modeling and the Detailed Mechanism of Ring Closure

2014 ◽  
Vol 118 (51) ◽  
pp. 12205-12220 ◽  
Author(s):  
Grant J. McIntosh ◽  
Douglas K. Russell
Keyword(s):  
Kinetic Modeling ◽  
Hydrogen Abstraction ◽  
Ring Closure ◽  
Detailed Mechanism

scholarly journals Arsenic Removal by Advanced Electrocoagulation Processes: The Role of Oxidants Generated and Kinetic Modeling

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 928
Author(s):  
Micah Flor V. Montefalcon ◽  
Meliton R. Chiong ◽  
Augustus C. Resurreccion ◽  
Sergi Garcia-Segura ◽  
Joey D. Ocon
Keyword(s):  
Kinetic Modeling ◽  
Arsenic Removal ◽  
Fold Increase ◽  
Electrochemical Treatment ◽  
Promising Alternative ◽  
Iron Electrodes ◽  
Removal Capacity ◽  
Naturally Occurring ◽  
Treatment Technologies

Arsenic (As) is a naturally occurring element in the environment that poses significant risks to human health. Several treatment technologies have been successfully used in the treatment of As-contaminated waters. However, limited literature has explored advanced electrocoagulation (EC) processes for As removal. The present study evaluates the As removal performance of electrocoagulation, electrochemical peroxidation (ECP), and photo-assisted electrochemical peroxidation (PECP) technologies at circumneutral pH using electroactive iron electrodes. The influence of As speciation and the role of oxidants in As removal were investigated. We have identified the ECP process to be a promising alternative for the conventional EC with around 4-fold increase in arsenic removal capacity at a competitive cost of 0.0060 $/m3. Results also indicated that the rate of As(III) oxidation at the outset of electrochemical treatment dictates the extent of As removal. Both ECP and PECP processes reached greater than 96% As(III) conversion at 1 C/L and achieved 86% and 96% As removal at 5 C/L, respectively. Finally, the mechanism of As(III) oxidation was evaluated, and results showed that Fe(IV) is the intermediate oxidant generated in advanced EC processes, and the contribution of •OH brought by UV irradiation is insignificant.

The effects of estradiol and testosterone on renal tissues oxidative after central injection of angiotensin II in female doca – salt treated rats

2018 ◽  
Vol 37 (3) ◽  
Author(s):  
Marzieh Kafami ◽  
Mahmoud Hosseini ◽  
Saeed Niazmand ◽  
Esmaeil Farrokhi ◽  
Mosa Al-Reza Hajzadeh ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Sex Hormones ◽  
Active Oxygen Species ◽  
Oxygen Species ◽  
Research Needs ◽  
Ang Ii ◽  
Detailed Mechanism ◽  
Female Wistar Rats

Abstract Background Although numerous studies have proven that estrogen (Est) has a protective effect on the development of hypertension, more research needs to be done to show its detailed mechanism in a variety of hypertension. The important role of active oxygen species in blood pressure is well defined. We examined whether or not sex hormones change the growth of reactive oxygen species (ROS) ‎in kidneys after central microinjection of angiotensin II (Ang II).‎ Materials and methods Female Wistar rats, 8 weeks old (200 ± 10 g) were used in this study. The animal groups were (1) Sham, (2) Ovariectomy (OVX), (3) Sham-Hypertension (Sham-Hyper), (4) OVX-Hypertension (OVX-Hyper), (5) Sham-Hyper-Est, (6) OVX-Hyper-Est‎;‎ (7) Sham-Hyper-Testosterone (Tst) and (8) OVX-Hyper-Tst. Solutions of 1% NaCl and 0.1 KCl ‎were used and desoxycorticostrone (doca-salt) was injected (45 mg/kg) 3 times a week in Hypertension groups. Estradiol and Tst (2 mg/kg and ‎5 mg/kg‎; daily; subcutaneously) for 4 weeks. Ang II (50 μM, 5 μL) was microinjected by intracerebroventricular ( i.c.v.) infusion and malondialdehyde (MDA) and thiol in the kidneys were measured. Results MDA in the kidneys was increased by Ang II and doca-salt treatments. Both estradiol and Tst decreased the kidney’s MDA. The level of thiol was higher in Hyper ‎groups and reversed after treatment with estradiol and Tst. Conclusions Our findings suggest that central effect of Ang II on blood pressure and kidney ‎disease is accompanied with increased levels of oxidative stress in the kidneys. Indeed sex hormones change the ROS level in the kidneys after central ‎microinjection of Ang II.‎‎

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

scholarly journals On the Importance of the Thiazole Nitrogen in Epothilones: Semisynthesis and Microtubule-Binding Affinity of Deaza-Epothilone C

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 499-509
Author(s):  
Adriana Edenharter ◽  
Lucie Ryckewaert ◽  
Daniela Cintulová ◽  
Juan Estévez-Gallego ◽  
José Fernando Díaz ◽  
...  
Keyword(s):  
Decisive Role ◽  
Ring Closure ◽  
Side Chain ◽  
Microtubule Binding ◽  
Acid Fragment ◽  
Epothilone A ◽  
Thiophene Moiety ◽  
Free Energy Of Binding

Deaza-epothilone C, which incorporates a thiophene moiety in place of the thiazole heterocycle in the natural epothilone side chain, has been prepared by semisynthesis from epothilone A, in order to assess the contribution of the thiazole nitrogen to microtubule binding. The synthesis was based on the esterification of a known epothilone A-derived carboxylic acid fragment and a fully synthetic alcohol building block incorporating the modified side chain segment and subsequent ring-closure by ring-closing olefin metathesis. The latter proceeded with unfavorable selectivity and in low yield. Distinct differences in chemical behavior were unveiled between the thiophene-derived advanced intermediates and what has been reported for the corresponding thiazole-based congeners. Compared to natural epothilone C, the free energy of binding of deaza-epothilone C to microtubules was reduced by ca. 1 kcal/mol or less, thus indicating a distinct but non-decisive role of the thiazole nitrogen in the interaction of epothilones with the tubulin/microtubule system. In contrast to natural epothilone C, deaza-epothilone C was devoid of antiproliferative activity in vitro up to a concentration of 10 μM, presumably due to an insufficient stability in the cell culture medium.

The Role of Nrf2 in D-Galactose-Induced Cardiac Aging in Mice: Involvement of Oxidative Stress

Gerontology ◽  
2020 ◽  
pp. 1-10
Author(s):  
Xilan Yang ◽  
Jian Jia ◽  
Ling Ding ◽  
Zhen Yu ◽  
Chen Qu
Keyword(s):  
Oxidative Stress ◽  
Developed Countries ◽  
Antioxidative Effect ◽  
Cardiac Aging ◽  
Detailed Mechanism ◽  
Candidate Drug ◽  
Nrf2 Activator ◽  
And Oxidative Stress ◽  
Aging Cell

<b><i>Introduction:</i></b> Cardiac aging is the major risk factor for advanced heart disease, which is the leading cause of death in developed countries, accounting for &#x3e;30% of deaths worldwide. <b><i>Objective:</i></b> To discover the detailed mechanism of cardiac aging and develop an effective therapeutic candidate drug to treat or delay cardiac aging. <b><i>Methods:</i></b> We used D-galactose to induce cardiac aging in Nrf2<sup>+/+</sup> and Nrf2<sup>–/–</sup> mice, and then treated these mice with vehicle or the Nrf2 activator, CDDO-imidazolide (CDDO-Im). <b><i>Results and Conclusions:</i></b> D-galactose injection significantly induced cardiac aging, cell apoptosis, and oxidative stress in Nrf2<sup>+/+</sup> mice, all of which were further exacerbated in Nrf2<sup>–/–</sup> mice. CDDO-Im treatment can effectively weaken oxidative stress and enhance the activities of antioxidant enzymes, but CDDO-Im lost its antioxidative effect in the Nrf2<sup>–/–</sup> mice. Nrf2 activator CDDO-Im could therefore effectively protect against D-galactose-induced cardiac aging by inhibiting oxidative stress, suggesting that CDDO-Im might be a potential and promising therapeutic candidate drug to treat cardiac aging.

Detailed kinetics of hydrogen abstraction from trans-decalin by OH radicals: the role of hindered internal rotation treatment

2020 ◽  
Vol 22 (44) ◽  
pp. 25740-25746
Author(s):  
Tam V.-T. Mai ◽  
Lam K. Huynh
Keyword(s):  
Master Equation ◽  
Hydrogen Abstraction ◽  
Kinetic Mechanism ◽  
Oh Radicals ◽  
Rate Model ◽  
Wide Range ◽  
Detailed Kinetics ◽  
Kinetics Of ◽  
Detailed Kinetic Mechanism

The detailed kinetic mechanism of the trans-decalin + OH reaction is firstly investigated for a wide range of conditions (T = 200–2000 K & P = 0.76–76000 Torr) using the M06-2X/aug-cc-pVTZ level and stochastic RRKM-based Master equation rate model.

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