Estrogen- and Progesterone (P4)-Mediated Epigenetic Modifications of Endometrial Stromal Cells (EnSCs) and/or Mesenchymal Stem/Stromal Cells (MSCs) in the Etiopathogenesis of Endometriosis

Endometriosis is a common chronic inflammatory condition in which endometrial tissue appears outside the uterine cavity. Because ectopic endometriosis cells express both estrogen and progesterone (P4) receptors, they grow and undergo cyclic proliferation and breakdown similar to the endometrium. This debilitating gynecological disease affects up to 15% of reproductive aged women. Despite many years of research, the etiopathogenesis of endometrial lesions remains unclear. Retrograde transport of the viable menstrual endometrial cells with retained ability for attachment within the pelvic cavity, proliferation, differentiation and subsequent invasion into the surrounding tissue constitutes the rationale for widely accepted implantation theory. Accordingly, the most abundant cells in the endometrium are endometrial stromal cells (EnSCs). These cells constitute a particular population with clonogenic activity that resembles properties of mesenchymal stem/stromal cells (MSCs). Thus, a significant role of stem cell-based dysfunction in formation of the initial endometrial lesions is suspected. There is increasing evidence that the role of epigenetic mechanisms and processes in endometriosis have been underestimated. The importance of excess estrogen exposure and P4 resistance in epigenetic homeostasis failure in the endometrial/endometriotic tissue are crucial. Epigenetic alterations regarding transcription factors of estrogen and P4 signaling pathways in MSCs are robust in endometriotic tissue. Thus, perspectives for the future may include MSCs and EnSCs as the targets of epigenetic therapies in the prevention and treatment of endometriosis. Here, we reviewed the current known changes in the epigenetic background of EnSCs and MSCs due to estrogen/P4 imbalances in the context of etiopathogenesis of endometriosis

Reaction engineering of oxidative coupling of methane: Experimental observations and analysis of the impacts of operating parameters

Performance of Oxidative Coupling of Methane (OCM) reactor using the research benchmark Mn-Na2WO4/SiO2 catalyst under various sets of operating conditions was experimentally investigated. In particular, the impacts of varying the operating parameters (630 combination-sets) namely; reactor set-temperature (in 6 levels in the range of 750–875 °C), feed flow-rate (in 5 levels in the range representing GHSV -Gas Hourly Space Velocity- of 9600-19200 cm3 g−1 h−1), methane-to-oxygen ratio (CH4/O2 in 7 levels in the range of 1.5–10), and inert gas dilution (in 3 levels at 0%, 25% and 50%) on the recorded trends of methane-conversion and selectivity and yield of the desired products (C2: C2H4&C2H6) were systematically reviewed. The performed experimental analysis enabled determining the impact of each investigated parameter as well as their interactive impacts through a carefully designed set of experiments. The novel proposed contour graphs visualized how the temperature and methane-to-oxygen ratio for instance directly influence the contribution of the catalyst or indirectly affect the reactor performance in synergy with the variation of dilution and feed flow due to their thermal impacts via affecting the intensity of the gas-phase and catalytic reactions in reactor-scale. It was demonstrated that in wide ranges of variation of these operating parameters, the recorded OCM reactor performance for instance in terms of the observed selectivity represent the interactive impacts of the intrinsic characters of the catalyst and the reactor's characteristics such as its dimension and thermal capacity. Therefore, these aspects should be carefully considered in design of experiments and in the interpretation of the experimental observations for the research purposes as well as in the design and operation of large-scale reactors

Feasibility study of the Mn Na2WO4 SiO2 catalytic system for the oxidative coupling of methane in a fluidized bed reactor

The catalytic system Mn Na2WO4 SiO2, known for its relatively stable performance for oxidative coupling of methane OCM , has been thoroughly investigated in the past. In order to evaluate its catalytic performance, micro fixed bed reactors were used almost exclusively. This study aims to answer the question of whether this catalytic system would be applicable on a larger scale using a miniplant fluidized bed quartz glass reactor. Special consideration was given for finding the optimal operating conditions and investigating whether catalyst abrasion and agglomeration could be limiting factors. In this study different compositions of the Mn Na2WO4 SiO2 catalyst were tested. High sodium content catalysts were difficult to fluidize at the optimal reaction temperature due to severe agglomeration by melting. Low sodium content catalysts showed low selectivity to C2 hydrocarbons. Catalysts containing intermediate levels of sodium were used for detailed testing as they showed promising performance as well as good fluidizability. The influence of the different reaction parameters on performance was tested, resulting in 19.4 C2 yield at 40 C2 selectivity. Catalysts before and after reaction were characterized regarding composition, crystalline phases, surface morphology and thermal stability. After time on stream, all catalysts exhibited a reduction in specific surface area, changes in Mn valence state Mn amp; 948; 2 amp; 8804; amp; 948; amp; 8804; 3 and changes in morphology due to grain growt

Experimental investigation of fluidized-bed reactor performance for oxidative coupling of methane

Performance of the oxidative coupling of methane in fluidized-bed reactor was experimentally investigated using Mn-Na2WO4/SiO2, La2O3/CaO and La2O3-SrO/CaO catalysts. These catalysts were found to be stable, especially Mn-Na2WO4/SiO2 catalyst. The effect of sodium content of this catalyst was analyzed and the challenge of catalyst agglomeration was addressed using proper catalyst composition of 2%Mn-2.2%Na2WO4/SiO2. For other two catalysts, the effect of Lanthanum-Strontium content was analyzed and 10%La2O3–20%SrO/CaO catalyst was found to provide higher ethylene yield than La2O3/CaO catalyst. Furthermore, the effect of operating parameters such as temperature and methane to oxygen ratio were also reviewed. The highest ethylene and ethane (C2) yield was achieved with the lowest methane to oxygen ratio around 2. 40.5% selectivity to ethylene and ethane and 41% methane conversion were achieved over La2O3-SrO/CaO catalyst while over Mn-Na2WO4/SiO2 catalyst, 40% and 48% were recorded, respectively. Moreover, the consecutive effects of nitrogen dilution, ethylene to ethane production ratio and other performance indicators on the down-stream process units were qualitatively discussed and Mn-Na2WO4/SiO2 catalyst showed a better performance in the reactor and process scale analysis

Experimental investigation of fluidized-bed reactor performance for oxidative coupling of methane

Performance of the oxidative coupling of methane in fluidized-bed reactor was experimentally investigated using Mn-Na2WO4/SiO2, La2O3/CaO and La2O3-SrO/CaO catalysts. These catalysts were found to be stable, especially Mn-Na2WO4/SiO2 catalyst. The effect of sodium content of this catalyst was analyzed and the challenge of catalyst agglomeration was addressed using proper catalyst composition of 2%Mn-2.2%Na2WO4/SiO2. For other two catalysts, the effect of Lanthanum-Strontium content was analyzed and 10%La2O3–20%SrO/CaO catalyst was found to provide higher ethylene yield than La2O3/CaO catalyst. Furthermore, the effect of operating parameters such as temperature and methane to oxygen ratio were also reviewed. The highest ethylene and ethane (C2) yield was achieved with the lowest methane to oxygen ratio around 2. 40.5% selectivity to ethylene and ethane and 41% methane conversion were achieved over La2O3-SrO/CaO catalyst while over Mn-Na2WO4/SiO2 catalyst, 40% and 48% were recorded, respectively. Moreover, the consecutive effects of nitrogen dilution, ethylene to ethane production ratio and other performance indicators on the down-stream process units were qualitatively discussed and Mn-Na2WO4/SiO2 catalyst showed a better performance in the reactor and process scale analysis

Oxidative Coupling of Methane - Still a Challenge for Catalyst Development and Reaction Engineering

Oxidative coupling of methane (OCM) to ethylene was studied using Li/MgO as model catalyst. The catalyst showed uncontrollable deactivation, regardless what precursor and method were used for its preparation. For the development of an OCM process another catalyst, Na2WO4/Mn/SiO2, was chosen. Kinetic isotope measurements and studies in a TAP reactor revealed the similarity of the reaction mechanisms at both catalysts, although they are completely different materials. The selectivity was largely controlled by total oxidation reactions of intermediates and products that can only be suppressed by a low partial pressure of oxygen in the reaction mixture. This is an abstract of a paper presented at the DGMK Conference (Dresden, Germany 10/9-11/2013)