Kinetics of oxidation of MoO2 to MoO3 by oxygen at elevated temperatures

The oxidation kinetics of MoO2 to MoO3 was investigated in the temperature range 674-791K and in the oxygen partial pressure range 8.1-30.4 kPa. Weight increase during the reaction was determined by thermogravimetric analysis with a microelectronic microbalance. The reaction is 0.6th-order with respect to oxygen concentration and the activation energy was found to be 148 kJ/mole. The data obtained gave a better understanding of the oxidation kinetics of MoS2. By applying the law of additive reaction times to the data for pellets an equation was derived that relates fractional conversion and time. This equation could be applied in isothermal conditions or to the diffusion of reacting gas through the pores of the product layer in non-isothermal conditions. The temperature rise was a result of the heat of the reaction and was calculated by applying a heat balance to the system. The effects of sintering and crack formation on the fractional conversion were also investigated. The findings should be taken into account when designing equipment and choosing operational conditions for the roasting of MoS2

Evaluation of the potential aphrodisiac activity of sesquiterpenoids from roots of Ferula huber-morathii Peşmen in male rats

PubMed: 322987512-s2.0-85083513322Ethnopharmacological relevance: Several species of Ferula L. genus have been used in traditional Turkish medicine as aphrodisiac to treat male sexual dysfunction. Especially, roots and oleo gum resin of F. elaeochytris Korovin, F. communis L., F. assa-foetida L. and F. gummosa Boiss. were claimed to be used for aphrodisiac activity, menstrual regulation and treatment of gastric pain in Anatolia. Ferula L. is represented by 23 taxa in Turkey, 13 of which are endemic species. F. huber-morathii Peşmen (FHM), an endemic plant, is popularly known as ‘‘helizan, çağşır’’. Aim of the study: This study aimed to isolate sesquiterpenoids from the roots of Ferula huber-morathii (FHM) and to confirm their aphrodisiac potential in male rats. Material and methods: In a preliminary experiment, the effects of aqueous (H2O) and chloroform (CHCl3) extracts of FHM were tested for their potential aphrodisiac activities in male rats. Then, sesquiterpene derivatives were isolated from the active chloroform extract of FHM roots (FHM-R) and characterized (TLC, 1D, 2D NMR, HR-MS and CD). Moreover, some of the isolates with adequate quantities were evaluated for their possible aphrodisiac effects on male rats. Single doses (10 mg/kg BW) of sildenafil citrate (SC, positive control), gummosin, mogoltavidin, deacetylkellerin, ferukrin acetate with kellerin, elaeochytrin-A and ferutinin were administered orally by gavages to male Wistar albino rats. Mount latency (ML), mount frequency (MF), intromission latency (IL), intromission frequency (IF), ejaculation latency (EL) and postejaculatory interval (PEI) were studied. In addition, copulatory efficiency (CE) and intercopulatory efficiency (ICE) were calculated. Results: The preliminary experiment revealed that the chloroform extract was the main source of the active compounds as it showed the higher aphrodisiac activity while the aqueous extract was found to be inactive. Eleven sesquiterpene derivatives, viz. gummosin, mogoltavidin, farnesiferol A, deacetylkellerin, ferukrin acetate, kellerin, teuclatriol, feruhermonin C, ferutinin, elaeochytrin A and teferidin, were isolated from the FHM-CHCl3 extract. Oral administration of deacetylkellerin, elaeochytrin-A and ferutinin significantly increased MF and IF. The ML and IL were significantly reduced, and ejaculation latencies were prolonged. Administration of these sesquiterpenoids also reduced the PEI. The present results revealed that ferutinin was the most effective aphrodisiac compound compared to other sesquiterpenoids. The results of 10 mg/kg of ferutinin are comparable to SC, the positive control. The results revealed that gummosin, mogoltavidin and ferukrin acetate with kellerin did not significantly alter the aphrodisiac parameters. Conclusions: This study has established that the CHCl3 extract of FHM root contains sesquiterpene derivatives, especially coumarin ethers and benzoic esters. Findings of the present study demonstrate that the chloroform extract and some of the sesquiterpene derivatives significantly stimulates sexual behavior in male rats, thus suggesting that F. huber-morathii possesses an aphrodisiac activity. © 2020 Elsevier B.V.Ege Ãœniversitesi: 13-ECZ-015The plant material was collected in the scope of Scientific Research Projects Directorate of Ege University (Project No: 13-ECZ-015 ) and special thanks to Assoc. Prof. Bintuğ ÖZTÜRK for collection and identification of the plant material