1,721,207 research outputs found
Methanol selective oxidation to methyl formate over ReOx/CeO2 catalysts
No full textMethanol selective oxidation to methyl formate was investigated over ReOx/CeO2 catalysts in terms of Re loading and reaction mechanism. It was found that Re loading with monolayer dispersion on ceria exhibited promising reaction rate of methanol of 16 mmol g(cat.)(-1) h(-1) and methyl formate selectivity of about 90% at 513 K. The surface reaction of methanol, formaldehyde, and methyl formate over the ReOx/CeO2 catalyst was investigated by in situ Fourier transform infrared spectroscopy and it was revealed that the formate species, formed by the oxidation of adsorbed -OCH3 species, could act as the key reaction intermediate, which further reacted with gaseous methanol to form methyl formate and/or decompose into CO and CO2, depending on the reaction temperature
ReOx charge injection/blocking layers in organic electronic devices
No full textThe charge transport of rhenium oxide (ReOx) in organic electronic devices was investigated. The hole injection/transport was blocked and the electron injection/transport was enhanced with doping of ReOx in organic electronic devices. Thus the charge balance and efficiency of organic light-emitting diodes were improved; current efficiency of 2.7 cd A(-1) at 20 mA cm(-2) for the device with ReOx was higher than 1.5 cd A(-1) for the device without it. In the case of organic photovoltaic cells, the open-circuit voltage (V-oc), 0.58 V, was higher compared with the device without ReOx (0.44 V) due to the improvement of interface properties. The power conversion efficiency was increased to 2.27% by the combination of ReOx (increases V-oc) with poly(3,4-ethylenedioxythiophene) : poly(styrene-sulfonate) (improves hole transport to increase J(sc)) on the modification of the anode, higher than 1.85% for the device without ReOx.Physics, AppliedSCI(E)EI5ARTICLE38null4
Minimal cell death of reactive astrocytes after OGD/REOX.
No full text<p>Hippocampal astrocytes were grown on 24 well culture dishes and subjected to 2(1 µM) was present only during REOX. At the end of REOX, cells were loaded with calcein-AM (green) and PI (red). <b>A</b>. Representative images of live (calcein positive) and dead (PI positive) cells of normoxia (a, à), 5 h REOX (b, b`), 5 h REOX+HOE 642 (c, c`), 24 REOX (d, d`) or 24 REOX+HOE 642 (e, è). <b>B</b>. Summary of reactive astrocyte death from six wells from each experimental condition. Data are mean ± SEM. n = 6.</p
Increased NHE1 activity in hippocampal astrocytes following OGD/REOX.
No full text<p><b>A.</b> pH<sub>i</sub> changes were determined by BCECF-AM dye in astrocytes subjected to NH<sub>4</sub><sup>+</sup>/NH<sub>3</sub> prepulse-mediated acid-loading. Either normoxic astrocytes (left panel) or astrocytes at 2 h OGD (right panel) were exposed to 30 mM NH<sub>4</sub>Cl<sub>3</sub> (<b>a–c</b>), then returned to standard HCO<sub>3</sub><sup>–</sup>free HEPES-MEM solution (<b>c–e</b>). After an initial acidification, pH<sub>i</sub> recovery followed (<b>d–e</b>). The pH recovery rates were determined at ∼ 6.5 to normalize for the allosteric regulation of H<sup>+</sup> on NHE1 activity. A slope of the pH<sub> i</sub> changes following the prepulse was calculated as pH<sub>i</sub> recovery rate (solid or dashed line). For HOE 642 treatment, the drug was present throughout the experiment. <b>B.</b> pH<sub>i</sub> (left panel) and pH<sub>i</sub> recovery rates (right panel) were summarized under normoxic control, 2 h OGD, or 1, 5, or 24 h REOX conditions. <b>C.</b> Summary data of NHE1-mediated recovery rates under normoxic and OGD/REOX conditions. The values of ∼20 cells from each coverslip/culture were averaged. The n values were the number of cultures under each condition and indicated as normoxia (9), normoxia+HOE 642 (6), 0 REOX (5), 0 REOX+HOE 642 (4), 1 h REOX (3), 1 h REOX+HOE 642 (4), 5 h REOX (5), 5 h REOX+HOE 642 (4), 24 h REOX (4) and 24 h REOX+HOE 642 (3). Data are expressed as mean ± SEM. *p<0.05 vs. corresponding untreated. # p<0.05 vs. corresponding untreated.</p
Окислительная конверсия метана на катализаторах ReOX/Al2O3
Get PDFReOx/alumina samples have been studied as catalysts for the oxidative conversion of methane. It was shown that the reaction of methane with an oxidized and then evacuated at this temperature (973 K, 1 h) samples leads to the formation of primarily C2H6, C2H4 and CO2, and then only CO
and C6H6. The formation of ethane and ethylene in the initial stage of the reaction of methane with
ReOx / alumina samples is the result of the reaction of oxidative condensation of methane with the
formation of ethane, followed by its dehydrogenation to ethylene. The reaction proceeds with the
participation of O-• ion-radical type (V-type defect) centers of the ReOx / aluminum-oxide structure
(CH4 + [O-•] = CH3
•
+ OH-
, 2CH3
•
= C2H6). CO2 is formed by the oxidation of methane with surface
oxygen forms (O2
2- and / and O2
-•) oxide structure. Direct oxidation of methane to methanol and further splitting of the latter to CO and H2 in our case are not excluded: CH4 + ReOx/Al2O3 = CO + 2H2
+ ReOx-1/Al2O3. It was shown that catalysts preliminarily oxidized at 973 K for 1 h in oxygen and then
evacuated at the same temperature for 1 h are characterized by ESR spectra belonging to the paramagnetic Re6+ ion with 5d1
unpaired electron and strong Re=O bond. The ESR spectra of this ion are
characterized by a hyperfine structure (A║ = 48.3 mT) due to the interaction of an unpaired electron
with 185.187Re magnetic nuclei having the spin of I = 5/2 and are easily observed at room temperature
for all samples. The ESR signals of these centers disappear after the interaction of samples evacuated
at high temperature (973 K) with methane. It was shown that high-temperature contact of this sample
with methane leads to the formation of centers that catalyze the oxidative dehydrocyclization of methane. The degree of oxidation of rhenium ions in these samples is less than 6+, and these ions are
coordinatively unsaturated. To maintain the activity of the catalyst, its regeneration is required. Activation of the catalyst is achieved by short-term heat treatment in oxygen flow followed by purging
with an inert gas (nitrogen, argon)
OXIDATIVE CONVERSION OF METHANE OVER ReOX/ALUMINA CATALYSTS
No full textReOx/alumina samples have been studied as catalysts for the oxidative conversion of methane. It was shown that the reaction of methane with an oxidized and then evacuated at this temperature (973 K, 1 h) samples leads to the formation of primarily C2H6, C2H4 and CO2, and then only CO and C6H6. The formation of ethane and ethylene in the initial stage of the reaction of methane with ReOx / alumina samples is the result of the reaction of oxidative condensation of methane with the formation of ethane, followed by its dehydrogenation to ethylene. The reaction proceeds with the participation of O-• ion-radical type (V-type defect) centers of the ReOx / aluminum-oxide structure (CH4 + [O-•] = CH3• + OH-, 2CH3• = C2H6). CO2 is formed by the oxidation of methane with surface oxygen forms (O22- and / and O2-•) oxide structure. Direct oxidation of methane to methanol and further splitting of the latter to CO and H2 in our case are not excluded: CH4 + ReOx/Al2O3 = CO + 2H2 + ReOx-1/Al2O3. It was shown that catalysts preliminarily oxidized at 973 K for 1 h in oxygen and then evacuated at the same temperature for 1 h are characterized by ESR spectra belonging to the paramagnetic Re6+ ion with 5d1 unpaired electron and strong Re=O bond. The ESR spectra of this ion are characterized by a hyperfine structure (A║ = 48.3 mT) due to the interaction of an unpaired electron with 185.187Re magnetic nuclei having the spin of I = 5/2 and are easily observed at room temperature for all samples. The ESR signals of these centers disappear after the interaction of samples evacuated at high temperature (973 K) with methane. It was shown that high-temperature contact of this sample with methane leads to the formation of centers that catalyze the oxidative dehydrocyclization of methane. The degree of oxidation of rhenium ions in these samples is less than 6+, and these ions are coordinatively unsaturated. To maintain the activity of the catalyst, its regeneration is required. Activation of the catalyst is achieved by short-term heat treatment in oxygen flow followed by purging with an inert gas (nitrogen, argon). Forcitation:Ismailov E.H., Osmanova S.N., Kerimova U.A. Oxidative conversion of methane over ReOx/Alumina catalysts. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 65-69.</jats:p
REOX: Effectiveness evaluation of re-exposure to oxaliplatin in patients with metastatic colorectal cancer.
No full text 764 Background: Colorectal cancer has high incidence and mortality rates. Treatment of metastatic colorectal adenocarcinoma has evolved since the approval of irinotecan, oxaliplatin and monoclonal antibodies with survival surpassing 30 months in contemporary trials. Nevertheless there is paucity of effective options after failure of these protocols. Thus re-exposure to previously used drugs became a treatment strategy. We aimed to evaluate the efficacy of retreatment with oxaliplatin in mCRC and its correlation with clinicopathological features. Methods: We retrospectively analyzed 83 patients with mCRC who underwent REOX treated at a single cancer center in Brazil. REOX was defined as a second trial of an oxaliplatin containing regimen after a previous failure. Primary endpoint was time to treatment failure (TTF) after REOX. Results: Median age of our cohort was 53.5y. Female/Male: 51.8%/48.2%. Primary colon was found in 67.5% while 32.5% had primary rectal adenocarcinoma. KRAS status was wild type in 57.8% and mutated in 39.8%. Exclusive hepatic metastasis was found in 19.3%. Median follow-up after REOX was 31m. Main chemotherapy regimen was mFOLFOX6 (84.3%). Bevacizumab and Cetuximab were used in 42.2% and 6% respectively. Most patients underwent REOX in third and fourth lines, 48.2% and 25.3% respectively. Median time to treatment failure (mTTF) after REOX was 6.04m. Overall survival was 10.04m. Disease control (CR + PR + SD) was observed in 56.6%, while 42.2% had progressive disease (PD). Reasons for interruption were as follows: PD (68.7%), toxicity (19.3%) and metastasectomy (2.4%). Patients who attained disease control had better OS (14.5m) compared with patients who had PD (14.5m versus 6.24m, p < 0.0001). Patients with exclusive hepatic metastasis had a trend to a better TTF compared to other metastasis sites (8.96m X 6.01m, p = 0.2). Regarding KRAS status, there was no difference in mTTF (wt 6.68m, mut 6.04m, p = 0.14). Conclusions: In the setting of pretreated mCRC patients where there are few options available, REOX remains an effective treatment, with mTTF of 6.04m in our cohort. This could be related to progression of cell clones sensitive to the drug after a time lapse since the previous exposure. </jats:p
Changes of [Na<sup>+</sup>]<sub>i</sub> and [Ca<sup>2+</sup>]<sub>i</sub> in hippocampal astrocytes following OGD/REOX.
No full text<p><b>A.</b> [Na<sup>+</sup>]<sub>i</sub> in hippocampal astrocyte cultures was determined with Sodium Green dye at 2 h normoxia or after 2 h OGD followed by 0, 1, 5, or 24 h REOX. HOE 642 (1 µM) was present during REOX only. Data are mean ± SEM. The values of ∼10 cells from each coverslip/culture were averaged. N of 3 cultures were for all groups except for normoxia, 0 h REOX, and 24 h REOX+HOE 642 (n = 4) or.5 h REOX and 24 h REOX (n = 5). *p<0.05 vs. normoxic control, # p<0.05 vs. corresponding untreated. <b>B.</b> [Ca<sup>2+</sup>]<sub>i</sub> in hippocampal astrocytes following OGD/REOX. [Ca<sup>2+</sup>]<sub>i</sub> in hippocampal astrocyte cultures was determined at 2 h normoxia or after 2 h OGD followed by 0, 1, 3, or 5 h REOX using fura-2 AM. HOE 642 (1 µM) or SEA 0400 (1 µM) was present during REOX only. The values of ∼10 cells from each coverslip/culture were averaged. Data are expressed as mean ± SEM. N of 4 cultures were for normoxia and the rest of other conditions were n of 3 cultures. *p<0.05 vs. normoxic control, # p<0.05 vs. corresponding untreated.</p
Role of ReOx Species in Ni-Re/Al2O3 Catalyst for Amination of Monoethanolamine
No full textThe role of ReOx species in Ni-Re/Al2O3 catalyst for amination of monoethanolamine (MEA) was investigated using a combination of experimental (Raman spectroscopy, in situ X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy line scan, and extended X-ray absorption fine structure) and theoretical (density functional theory (DFT)) methods. Characterization and simulation results indicate that rhenium oxide specie prefers to atomically disperse on the surface of NiO in calcined Ni-Re/Al2O3 catalyst. After reduction, the surface of metallic Ni is decorated by ReOx with multiple valence states; meanwhile, a small amount of Ni-Re alloy was detected by extended X-ray absorption fine structure (EXAFS). DFT results indicate that different-valent ReOx species in Ni-Re/Al2O3 catalyst have different functions during reaction. The high-valent ReOx (x >= 3) distributed on the Ni particle surface play an important role in decreasing the surface energy of Ni particle, thus stabilizing Ni particles against sintering and increasing the lifetime of Ni-Re/Al2O3 catalyst during amination reaction. The synergistic effect between Ni and low-valent ReOx (x < 3) sites facilitates the abstraction of hydrogen in MEA and improves the activity of Ni-Re/Al2O3 catalyst for MEA amination
A Comparative study on the Ru-ReOx catalyst supported on biochar derived from rice straw for production of value-added compounds from furan
No full text학위논문(석사)--아주대학교 일반대학원 :환경공학과,2021. 2이번 연구에서는 폐기물 기반의 바이오매스의 헤미셀룰로오스 성분에서 파생된 퓨란의 고부가가치화를 위해 두가지 다른 대기 하에서 생성된 바이오차를 촉매로 이용하였습니다. 바이오차는 볏짚(RSB)을 원료로 표면적와 다공성을 수정시키기 위해 N2와 CO2에서 열분해 하에 생성되었습니다. 그 이후에 바이오차를 촉매 지지체로 사용하여 이원기능성 Ru-ReOx 촉매에 담지시켜 제조하였습니다. 바이오차에 담지된 Ru-ReOx 촉매 (Ru-ReOx /RSB)는 기존의 활성탄이 담지된 촉매 (Ru-ReOx /AC)와 비교되었습니다. 바이오차가 담지된 촉매(Ru-ReOx /RSB)는 활성탄에 담지된 촉매 (Ru-ReOx /AC)와 비교하였을 경우, 환원성 차이를 보였으며 다른 형태의 Re 종이 함유되었는데, 이는 바이오차 내에 알칼리 금속 (K) 존재하기 때문입니다. 지지체의 환원성과 금속 분산은 바이오차의 생성 대기와 밀접하게 관련되었습니다. 특히, Ru–ReOx /RSB-CO2 촉매는 250~560 °C의 온도 범위에서 Ru–ReOx /RSB-N2¬ 촉매보다 24 % 더 많은 수소를 소비했습니다. 바이오차가 담지된 촉매(Ru-ReOx /RSB)의 경우, 활성탄이 담지된 촉매 (Ru-ReOx /AC)와 비교하였을 때 낮은 표면적을 형성하고 있는데, 이는 표면 금속 활성점이 12배 더 적은 것에 기인합니다. 퓨란에서 THF 및 1,4 부탄다이올의 전환에 대한 촉매들에 대한 활성점 당 반응속도(Reaction rate)도 측정되었습니다. 측정 결과를 살펴보면, Ru-ReOx / RSB-N2 촉매는 Ru-ReOx / RSB-CO2 촉매보다 2 배 더 활성이 높았으며 Ru-ReOx / AC 촉매보다 3 배 더 활성이 높은 것을 확인할 수 있었습니다. 따라서 이 연구는 바이오차 촉매의 촉매 특성을 수정하기 위한 간단한 전략을 제시하며 바이오매스 및 폐기물로부터 고부가가치 화학 물질 생산의 바이오차를 촉매로 사용하는 새로운 적용 가능성을 제안합니다. 그러므로, 이 결과는 또한 바이오리파이너리 분야인 폐기물 바이오매스의 전환에 따른 친환경공정 개발에 도움이 되며 고부가가치 화합물 생산에 있어 기존 촉매를 대체 가능한 바이오차의 잠재력을 강조하고자 합니다.Chapter 1. introduction 1
1.1. Background 1
1.2. Furan 4
1.3. Biochar and Application of biochar-based catalysts for various chemical reaction 6
Objective 11
Chapter 2. Materials and Methods 13
2.1. Materials 13
2.2. Catalyst preparation 14
2.3. Catalyst characterizaion 16
2.4. Catalyst evaluation and product analysis 19
Chapter 3. Result 24
3.1. Catalyst characterization of Ru–ReOx /RSB-N2, Ru–ReOx /RSB-CO2, and Ru–ReOx /AC catalysts. 24
3.2. Catalytic performance of the Ru–ReOx /RSB-N2, Ru–ReOx /RSB-CO2, and Ru–ReOx /AC catalysts in the production of 1, 4-butanediol from furan 37
Chapter 4. Conclusion 45
References 48
부록 58
요약 60MasterEngineered biochar under different environment was used as the catalytic material for the valorization of furan that can be derived from hemicellulosic portion of biomass generated from waste in this study. The biochar was made from pyrolysis using rice straw in N2 or CO2 atmosphere (RSB-N2 or RSB-CO2) to modify its properties including porosity and surface area. The biochars were employed as catalyst support for bifunctional Ru–ReOx catalyst. The biochar-supported Ru–ReOx catalysts (Ru–ReOx /RSB) were compared to a typical activated charcoal (AC)-supported Ru–ReOx catalyst (Ru–ReOx /AC). The biochar-supported catalysts had different reducibility and contained a different form of Re species from the AC-supported catalyst due to the existence of alkali metal (e.g., potassium) in the biochar catalysts. The reducibility and metal dispersion on the support were also highly associated with the atmosphere under which the biochar was made. The Ru–ReOx /RSB-CO2 consumed 24% more hydrogen than the Ru–ReOx /RSB-N2 at a comparable temperature range from 250 to 560 °C. The Ru–ReOx /RSB catalysts had 12 times the smaller number of surface metal sites than the Ru–ReOx /AC catalyst, attributed to their lower surface area. Reaction rate on a per site basis for the conversion of furan into tetrahydrofuran and 1, 4-butanediol was measured over the catalysts. In addition, the Ru–ReOx /RSB-N2 was 2 times more active than the Ru–ReOx /RSB-CO2 and 3 times more active than the Ru–ReO¬x /AC. This result shows not only a straightforward method to modify catalytic properties of biochar catalyst but also a new way using biochar to the production of value-added compounds from waste biomass. Thus, it shows potential of engineered biochar for replacing conventional catalysts used in biorefinery
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