Model-based catalyst selection for the oxidative coupling of methane in an adiabatic fixed-bed reactor

Adiabatic operation of catalytic fixed-bed reactors for oxidative coupling of methane (OCM) has been simulated using a detailed microkinetic and reactor model. For several catalysts (1%(wt) Sr/La2O3, 10%(wt) La-20%(wt) Sr/CaO, 4%(wt) Sn-2%(wt) Li/MgO, and 12%(wt) Mn-20%(wt) Na2WO4/SiO2), diverse in activity and selectivity toward C2+ products, operating conditions have been determined that maximize C2+ yield at low inlet temperature T-0 (<< 923 K). A prior analysis of light-off curves served as a guideline for optimal operating temperature ranges for each catalyst. Imposing a maximum temperature in the reactor (T-max <= 1273 K) suggested a limit for the catalytic performances, corresponding to 13% CH4 conversion and 61% C2+ selectivity at the reactor outlet for an active (T-0 = 723 K) Sr/La2O3 catalyst, and an improved 19% CH4 conversion and 82% C2+ selectivity for a less active (T-0 = 853 K) NaMnW/SiO2 catalyst. The obtained results indicated catalyst selectivity, rather than activity, as the key parameter for an industrially relevant adiabatic OCM process

ارزیابی کیفیت آزمون های چهار گزینه ای دروس تئوری عمومي گروه اندودانتیکس دانشکده دندانپزشکی قزوین در طی سال های تحصیلی 1388 تا 1396

Svrha je ovoga rada bila ispitati citotoksični, proapoptotski, antimigratorni i pro-antioksidacijski učinak metanolnih, acetonskih i etil-acetatnih ekstrakata dvaju vrsta lišaja, i to: Pseudevernia furfuracea i Platismatia glauca na tumorske stanične linije debelog crijeva (HCT-116 i SW-480). Citotoksični efekti na tumorskim staničnim linijama debelog crijeva uspoređeni su s onima na staničnoj liniji normalnih humanih fibroblasta (MRC-5). Citotoksičnost je ispitana MTT testom, stanična migracija Transwell esejom, dok je apoptoza praćena fluorescentnom metodom pomoću akridin narančastog bojila i etidijevog bromida. Prooksidacijski/antioksidacijski učinak praćen je spektrofotometrijskim mjerenjem koncentracije redoks parametara. Ispitani ekstrakti imali su značajan citotoksični učinak na tumorske stanične linije, bez zapaženog utjecaja na normalnu staničnu liniju. Najjača citotoksičnost postignuta je nakon 72 h obrade staničnih linija ekstraktima vrste P. furfuracea (IC50= (21,2±1.3) µg/mL pri obradi HCT-116 stanica etil-acetatnim ekstraktom i IC50=(51.3±0.8) µg/mL pri obradi stanica SW-480 acetonskim ekstraktom). Ekstrakti P. furfuracea imali su značajan proapoptotski i prooksidacijski učinak, dok je metanolni ekstrakt te vrste imao najjači antimigratorni učinak na ispitane tumorske stanične linije. Svi ispitani ekstrakti vrste P. glauca imali su znatan citotoksični učinak na stanice HCT-116 nakon 72 h tretmana (IC50<40 μg/mL), dok su metanolni i acetonski ekstrakti imali citotoksični učinak na stanice SW-480 nakon 24 h, s izraženom proapoptotskom/nekrotskom aktivnošću. Svi navedeni efekti posljedica su induciranog oksidacijskog stresa u tretiranim stanicama. Može se zaključiti da ekstrakti lišaja bitno mijenjaju vijabilnost i migratorni potencijal ispitanih tumorskih staničnih linija karcinoma debelog crijeva. Dobiveni rezultati pokazuju da su stanice HCT-116 osetljivije na ispitane ekstrakte, pri čemu ekstrakti vrste P. furfuracea pokazuju bolji proapototski i antimigratorni učinak. Ispitane vrste lišaja mogu se smatrati izvorima antikancerogenih aktivnih tvari.The aim of this study is to investigate cytotoxic, proapoptotic, antimigratory and pro-antioxidant effects of methanol, acetone and ethyl acetate extracts of lichens Pseudevernia furfuracea and Platismatia glauca on colorectal cancer (HCT-116 and SW-480) cell lines. We compared the cytotoxic effects on colorectal cancer cells with the effects obtained from normal human fibroblast (MRC-5) cell line. Tetrazolium (MTT) test evaluated the cytotoxic effects, Transwell assay evaluated cell migration, acridine orange/ethidium bromide (AO/EB) fluorescent method followed the apoptosis, while prooxidant/antioxidant effects were determined spectrophotometrically through concentration of redox parameters. The tested extracts showed considerable cytotoxic effect on cancer cells with no observable cytotoxic effect on normal cells. Ethyl acetate and acetone extract of P. furfuracea induced the highest cytotoxicity (IC50=(21.2±1.3) μg/mL on HCT-116, and IC50=(51.3±0.8) μg/mL on SW-480 cells, respectively, after 72 h), with noteworthy apoptotic and prooxidant effects, and antimigratory potential of methanol extract. P. glauca extracts induced cytotoxic effects on HCT-116 cells after 72 h (IC50<40 μg/mL), while only methanol and acetone extracts had cytotoxic effects on SW-480 cells after 24 h, with proapoptotic/necrotic activity, as a consequence of induced oxidative stress. In conclusion, lichen extracts changed to a great extent cell viability and migratory potential of colorectal cancer cell lines. HCT-116 cells were more sensitive to treatments, P. furfuracea had better proapoptotic and antimigratory effects, and both investigated lichen species might be a source of substances with anticancer activity

Glutathione status in the blood of rats after reticulocytosis induced by phenylhydrazine and bleeding

In this experiment, we compared the in vivo effects of phenylhydrazine (PHZ) and bleeding treatment on the redox status and glutathione antioxidative mechanism parameters in the plasma and red blood cells (RBC) of rats. Results showed a lower level of reactive oxygen species (ROS), a higher level of lipid peroxidation and the effective antioxidative role of the glutathione system in the blood of bleeding rats. PHZ-treatment induced higher concentrations of ROS and an accumulation of oxidized glutathione in the plasma, while the glutathione system showed a satisfactory antioxidative capacity in the RBC of rats. When comparing the two anemic groups, the PHZ-treated rats showed marked oxidative stress in the plasma.Cilj ovog rada je bio da se isprate in vivo efekti fenilhidrazinom (PHZ) i krvarenjem indukovane retikulocitoze na parametre redoks i glutationskog antioksidativnog statusa u plazmi i crvenim krvnim ćelijama (RBC) pacova. Rezultati pokazuju niži nivo reaktivnih vrsta kiseonika (ROS), viši nivo lipidne peroksidacije i efikasnu antioksidacionu ulogu glutationskog sistema u krvi iskvavljenih pacova. Tretman PHZom prouzrokovao je više koncentracije ROSa i akumulaciju oksidovanog glutationa u plazmi, dok je glutationski sistem pokazao efikasan antioksidativni kapacitet u RBCu pacova. Kada se uporede dve anemične grupe, izraženiji oksidacioni stres se javlja u plazmi pacova tretiranih PHZom.Projekat ministarstva br. 143035

Uloga klastera u savremenom obrazovanju u oblasti bioekonomije

Razvoj konkurentnosti na Evropskom i svetskomtržištu doveo je do pojave klastera kao oblika povezivanjakompanija iz srodnih delatnosti sa naučno-istraživačkiminstitucijama. Ideja klastera je da podstiču saradnju, ali ikonkurentnost i specijalizaciju u određenoj oblasti. Značajnuulogu u formiranju klastera ima sektor obrazovanja, tačnijevisokoškolske ustanove. Kroz obrazovanje grade sevisokokvalifikovani stučnjaci koji predstavljaju temelj zaorganizovanje i formiranje klastera. Intelektualni kapital kaoskup svih znanja unutar jedne organizacije, učestvuje uobrazovanju zaposlenih, i doprinosi građenju konkurentskeprednosti organizacije. Budući stručnjaci bi trebalo da raspolažutakozvanim intelektualnim materijalom u obliku informacija,iskustva, znanja itd, na osnovu kojih se ostvaruje konkurentnost.Cilj ovog rada bio je ukazivanje na značaj i potencijalvisokoškolskih ustanova u kreiranju klastera u Republici Srbiji.Istraživanjem je obuhvaćeno 8 državnih i 9 privatnihUniverziteta u okviru kojih se nalazi ukupno 95 državnih,odnosno 57 privatnih fakulteta. Rezultati istraživanja pokazujuda se veliki potencijal za razvoj klastera nalazi upravo u okviruuniverziteta. Posebno se izdvajaju pojedine oblasti u razvoju izsfere bioekonomije, kao što su ekologija i zaštita životne sredine,koje postaju sve značajnije privatnim i državnim univerzitetimau Srbiji, i izučavaju se kroz module

The Removal of Ni2+ and Cd2+ -ions onto Synthetic Mineral Based Composite Functionalized by Polyethylenimine

This study presents the synthesis of porous cordierite- based ceramics and its surface activation by polyethylenimine/nano-CeO2 for the heavy metal removal. The synthesis was carried out by the addition of following powders: MgO, Al2O3, and SiO2 in 2:2:5 molar ratios, respectively. The oxide(s) mixture was further processed in two sequential stages: i) ball milled in the ethanol for 40 minutes and palletized under the pressure of 3 t/cm2, as a pre-sintering process, and ii) the pallets were further sintered for 2h in the air atmosphere at 1350 oC, under a heating rate of 20 oC/min. The sintered mineral composite was crashed and sieved, and mixed with 20 wt % of nanocellulose, as a pore forming agent. Nanocellulose mixture was pressed into pallets under 5 t/cm2 and sintered at 700 oC, under a heating rate of 5 oC/ min. The obtained synthetic cordierite was further tested as the adsorbent activated by polyethylenimine/ nano-CeO2 for the removal of Ni2+ and Cd2+ -ions. The adsorption isotherms, kinetics models, and thermodynamic parameters were also analyzed, manifesting that the adsorption is a spontaneous and endothermic process. The phase composition of the pristine and activated cordierite was analyzed by the X-ray diffraction method (XRD), Fourier transformation infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). This work has shed light on the mechanism of heavy metals removal from the aquatic medium using the novel hybrid (nano)synthesized material

Risks in the Role of Co-Creating the Future of Tourism in “Stigmatized” Destinations

The primary goal of this paper was to investigate the strength of the influence of different types of risk on the travelers’ intention to visit destinations in future, that are, prejudiced due to COVID-19, marked as “stigmatized”, “isolated”, or “risky destinations”. Field interview research was conducted at the “Belgrade Nikola Tesla Airport” (Serbia). The results obtained by multiple regression analysis showed that all types of risks influenced the intention of travelers, with financial risk showing a more significant impact. Canonical discriminant analysis indicated that men were most afraid of human induced risk, service quality risk, natural disaster and COVID-19 risk, and they chose safer destinations. Among the women, the biggest fear was financial risk, socio-psychological risk, and food safety risk. Older respondents and those under the influence of external factors decided on safer destinations, while financial status did not play a significant role in predicting the choice of destination. The selection of the destination according to the degree of security was determined by the ordinal regression methodology. The entire research presents a certain novelty, because so far in the numerous studies on the topic of the negative consequences of COVID-19 on tourism, there has been no discussion of stigmatized or risky destinations that received that epithet, and were therefore negatively and unfairly marked in the minds of tourists for future visits

Supplementary material for the article: Rusmirović, J.D., Obradović, N., Perendija, J., Umićević, A., Kapidžić, A., Vlahović, B., Pavlović, V., Marinković, A.D., Pavlović, V.B., 2019. Controllable synthesis of Fe3O4-wollastonite adsorbents for efficient heavy metal ions/oxyanions removal. Environ Sci Pollut Res 26, 12379–12398. https://doi.org/10.1007/s11356-019-04625-0

Related to: [http://dais.sanu.ac.rs/handle/123456789/5764]Supplementary material for: [http://dx.doi.org/10.1007/s11356-019-04625-0

Glutathione status in the blood of rats after reticulocytosis induced by phenylhydrazine and bleeding

In this experiment, we compared the in vivo effects of phenylhydrazine (PHZ) and bleeding treatment on the redox status and glutathione antioxidative mechanism parameters in the plasma and red blood cells (RBC) of rats. Results showed a lower level of reactive oxygen species (ROS), a higher level of lipid peroxidation and the effective antioxidative role of the glutathione system in the blood of bleeding rats. PHZ-treatment induced higher concentrations of ROS and an accumulation of oxidized glutathione in the plasma, while the glutathione system showed a satisfactory antioxidative capacity in the RBC of rats. When comparing the two anemic groups, the PHZ-treated rats showed marked oxidative stress in the plasma.Cilj ovog rada je bio da se isprate in vivo efekti fenilhidrazinom (PHZ) i krvarenjem indukovane retikulocitoze na parametre redoks i glutationskog antioksidativnog statusa u plazmi i crvenim krvnim ćelijama (RBC) pacova. Rezultati pokazuju niži nivo reaktivnih vrsta kiseonika (ROS), viši nivo lipidne peroksidacije i efikasnu antioksidacionu ulogu glutationskog sistema u krvi iskvavljenih pacova. Tretman PHZom prouzrokovao je više koncentracije ROSa i akumulaciju oksidovanog glutationa u plazmi, dok je glutationski sistem pokazao efikasan antioksidativni kapacitet u RBCu pacova. Kada se uporede dve anemične grupe, izraženiji oksidacioni stres se javlja u plazmi pacova tretiranih PHZom.Projekat ministarstva br. 143035

Controllable synthesis of Fe3O4-wollastonite adsorbents for efficient heavy metal ions/oxyanions removal

Iron oxide, in the form of magnetite (MG)–functionalized porous wollastonite (WL), was used as an adsorbent for heavy metal ions (cadmium and nickel) and oxyanions (chromate and phosphate) removal from water. The porous WL was synthesized from calcium carbonate and siloxane by controlled sintering process using low molecular weight submicrosized poly(methyl methacrylate) as a pore-forming agent. The precipitation of MG nanoparticles was carried out directly by a polyol-medium solvothermal method or via branched amino/carboxylic acid cross-linker by solvent/nonsolvent method producing WL/MG and WL-γ-APS/MG adsorbents, respectively. The structure/properties of MG functionalized WL was confirmed by applying FTIR, Raman, XRD, Mössbauer, and SEM analysis. Higher adsorption capacities of 73.126, 66.144, 64.168, and 63.456 mg g−1 for WL-γ-APS/MG in relation to WL/MG of 55.450, 52.019, 48.132, and 47.382 mg g−1 for Cd2+, Ni2+, phosphate, and chromate, respectively, were obtained using nonlinear Langmuir model fitting. Adsorption phenomena were analyzed using monolayer statistical physics model for single adsorption with one energy. Kinetic study showed exceptionally higher pseudo-second-order rate constants for WL-γ-APS/MG, e.g., 1.17–13.4 times, with respect to WL/MG indicating importance of both WL surface modification and controllable precipitation of MG on WL-γ-APS.Peer reviewed version of the paper: [https://machinery.mas.bg.ac.rs/handle/123456789/4041

Risks in the Role of Co-Creating the Future of Tourism in &ldquo;Stigmatized&rdquo; Destinations

The primary goal of this paper was to investigate the strength of the influence of different types of risk on the travelers&rsquo; intention to visit destinations in future, that are, prejudiced due to COVID-19, marked as &ldquo;stigmatized&rdquo;, &ldquo;isolated&rdquo;, or &ldquo;risky destinations&rdquo;. Field interview research was conducted at the &ldquo;Belgrade Nikola Tesla Airport&rdquo; (Serbia). The results obtained by multiple regression analysis showed that all types of risks influenced the intention of travelers, with financial risk showing a more significant impact. Canonical discriminant analysis indicated that men were most afraid of human induced risk, service quality risk, natural disaster and COVID-19 risk, and they chose safer destinations. Among the women, the biggest fear was financial risk, socio-psychological risk, and food safety risk. Older respondents and those under the influence of external factors decided on safer destinations, while financial status did not play a significant role in predicting the choice of destination. The selection of the destination according to the degree of security was determined by the ordinal regression methodology. The entire research presents a certain novelty, because so far in the numerous studies on the topic of the negative consequences of COVID-19 on tourism, there has been no discussion of stigmatized or risky destinations that received that epithet, and were therefore negatively and unfairly marked in the minds of tourists for future visits