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61.
Reactions between Strontium-Substituted Lanthanum Manganite and Yttria-Stabilized Zirconia: II, Diffusion Couples 总被引:1,自引:0,他引:1
Kjersti Kleveland Mari-Ann Einarsrud Christian R. Schmidt Senem Shamsili Sonia Faaland Kjell Wiik Tor Grande 《Journal of the American Ceramic Society》1999,82(3):729-734
Formation of secondary phases and diffusion of cations in diffusion couples of yttria-stabilized zirconia and lanthanum manganite substituted with 0 to 60 mol% strontium have been studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. Only the primary phases were observed after 120 h at 1200°C, while formation of secondary phases was identified already after 1 h heat treatment at 1350°C. The phase composition of the reaction layer altered from La2 Zr2 O7 to SrZrO3 at increasing Sr content in La x Sr1- x MnO3 . The thickness of the reaction layer was increasing with heat treatment time. In diffusion couples of La0.4 Sr0.6 MnO3 formation of manganese oxide was observed in the perovskite layer after 1 h heat treatment at 1350°C, while isolated grains of SrZrO3 relatively deep inside the zirconia were observed after longer heat treatment time. Diffusion of Mn into zirconia was observed preferenced along grain boundaries in the early stage of the interface reaction. 相似文献
62.
Luiz F.G. Setz Isabel Santacruz M. Teresa Colomer Sonia R.H. Mello-Castanho Rodrigo Moreno 《Journal of the European Ceramic Society》2010,30(14):2897-2903
Lanthanum chromite (LaCrO3) is currently the most widely studied material as interconnector layers for solid oxide fuel cells (SOFC). The complexity of microstructures and geometries of SOFC devices, which are usually built-up by lamination of the different constitutive layers, make it necessary a precise control of processing parameters to achieve the desired combination of properties. Much effort has been devoted to the processing of electrodes and electrolytes but the other layers, such as that of interconnecting material, have received scarce attention. This work deals with the preparation and optimisation of the rheological behaviour of concentrated suspensions of Sr- and Co-doped LaCrO3 and the subsequent tape casting to produce homogeneous thin sheets to be used in the SOFC stack.The starting powder was produced by combustion synthesis from the corresponding nitrates and urea as a fuel, and had a final composition of La0.80Sr0.20Cr0.92Co0.08O3. These powders were dispersed in ethanol with commercial copolymers (Hypermer, KD6) to solids loading of up to 58 wt%. The binding system (BS) consisted of a mixture of a binder, polyvinyl butyral-co-vinyl alcohol-co-vinyl acetate (PVA-PVAc), and two plasticizers, polyethyleneglycol (PEG400) and benzylbutylphthalate (BBP). The effect of the binding system content and the binder-to-plasticizer ratio on the tape casting performance and the characteristics of the green and the sintered tapes, were studied, as well as the influence of the casting parameters (casting speed and blades height). 相似文献
63.
Michal Kowara Sonia Borodzicz-Jazdzyk Karolina Rybak Maciej Kubik Agnieszka Cudnoch-Jedrzejewska 《International journal of molecular sciences》2021,22(11)
Myocardial infarction is one of the major causes of mortality worldwide and is a main cause of heart failure. This disease appears as a final point of atherosclerotic plaque progression, destabilization, and rupture. As a consequence of cardiomyocytes death during the infarction, the heart undergoes unfavorable cardiac remodeling, which results in its failure. Therefore, therapies aimed to limit the processes of atherosclerotic plaque progression, cardiac damage during the infarction, and subsequent remodeling are urgently warranted. A hopeful therapeutic option for the future medicine is targeting and regulating non-coding RNA (ncRNA), like microRNA, circular RNA (circRNA), or long non-coding RNA (lncRNA). In this review, the approaches targeted at ncRNAs participating in the aforementioned pathophysiological processes involved in myocardial infarction and their outcomes in preclinical studies have been concisely presented. 相似文献
64.
65.
Silvia Buonvino Matteo Ciocci Dror Seliktar Sonia Melino 《International journal of molecular sciences》2021,22(11)
Photo-polymerized hydrogels are ideally suited for stem-cell based tissue regeneration and three dimensional (3D) bioprinting because they can be highly biocompatible, injectable, easy to use, and their mechanical and physical properties can be controlled. However, photo-polymerization involves the use of potentially toxic photo-initiators, exposure to ultraviolet light radiation, formation of free radicals that trigger the cross-linking reaction, and other events whose effects on cells are not yet fully understood. The purpose of this study was to examine the effects of hydrogen sulfide (H2S) in mitigating cellular toxicity of photo-polymerization caused to resident cells during the process of hydrogel formation. H2S, which is the latest discovered member of the gasotransmitter family of gaseous signalling molecules, has a number of established beneficial properties, including cell protection from oxidative damage both directly (by acting as a scavenger molecule) and indirectly (by inducing the expression of anti-oxidant proteins in the cell). Cells were exposed to slow release H2S treatment using pre-conditioning with glutathione-conjugated-garlic extract in order to mitigate toxicity during the photo-polymerization process of hydrogel formation. The protective effects of the H2S treatment were evaluated in both an enzymatic model and a 3D cell culture system using cell viability as a quantitative indicator. The protective effect of H2S treatment of cells is a promising approach to enhance cell survival in tissue engineering applications requiring photo-polymerized hydrogel scaffolds. 相似文献
66.
Michaela K. Back Sonia Ruggieri Eric Jacobi Jakob von Engelhardt 《International journal of molecular sciences》2021,22(12)
Onset and progression of Alzheimer’s disease (AD) pathophysiology differs between brain regions. The neocortex, for example, is a brain region that is affected very early during AD. NMDA receptors (NMDARs) are involved in mediating amyloid beta (Aβ) toxicity. NMDAR expression, on the other hand, can be affected by Aβ. We tested whether the high vulnerability of neocortical neurons for Aβ-toxicity may result from specific NMDAR expression profiles or from a particular regulation of NMDAR expression by Aβ. Electrophysiological analyses suggested that pyramidal cells of 6-months-old wildtype mice express mostly GluN1/GluN2A NMDARs. While synaptic NMDAR-mediated currents are unaltered in 5xFAD mice, extrasynaptic NMDARs seem to contain GluN1/GluN2A and GluN1/GluN2A/GluN2B. We used conditional GluN1 and GluN2B knockout mice to investigate whether NMDARs contribute to Aβ-toxicity. Spine number was decreased in pyramidal cells of 5xFAD mice and increased in neurons with 3-week virus-mediated Aβ-overexpression. NMDARs were required for both Aβ-mediated changes in spine number and functional synapses. Thus, our study gives novel insights into the Aβ-mediated regulation of NMDAR expression and the role of NMDARs in Aβ pathophysiology in the somatosensory cortex. 相似文献
67.
Sonia J. Parikh Sumit Kamat Margaret Phillips Samuel P. Boyson Thomas Yarbrough Dylan Davie Qinghai Zhang Karen C. Glass Manish B. Shah 《International journal of molecular sciences》2021,22(19)
Cytochromes P450 (CYP) are one of the major xenobiotic metabolizing enzymes with increasing importance in pharmacogenetics. The CYP2C9 enzyme is responsible for the metabolism of a wide range of clinical drugs. More than sixty genetic variations have been identified in CYP2C9 with many demonstrating reduced activity compared to the wild-type (WT) enzyme. The CYP2C9*8 allele is predominantly found in persons of African ancestry and results in altered clearance of several drug substrates of CYP2C9. The X-ray crystal structure of CYP2C9*8, which represents an amino acid variation from arginine to histidine at position 150 (R150H), was solved in complex with losartan. The overall conformation of the CYP2C9*8-losartan complex was similar to the previously solved complex with wild type (WT) protein, but it differs in the occupancy of losartan. One molecule of losartan was bound in the active site and another on the surface in an identical orientation to that observed in the WT complex. However, unlike the WT structure, the losartan in the access channel was not observed in the *8 complex. Furthermore, isothermal titration calorimetry studies illustrated weaker binding of losartan to *8 compared to WT. Interestingly, the CYP2C9*8 interaction with losartan was not as weak as the CYP2C9*3 variant, which showed up to three-fold weaker average dissociation constant compared to the WT. Taken together, the structural and solution characterization yields insights into the similarities and differences of losartan binding to CYP2C9 variants and provides a useful framework for probing the role of amino acid substitution and substrate dependent activity. 相似文献
68.
Bushra Bashir Muhammad Usman Khalid Muhammad Aadil Sonia Zulfiqar Muhammad Farooq Warsi Philips O. Agboola Imran Shakir 《Ceramics International》2021,47(3):3603-3613
NiO nanostructure was synthesized using a simple co-precipitation method and was embedded on reduced graphene oxide surface via ultrasonication. Structural investigations were made through X-ray diffraction (XRD) and functional groups were confirmed by Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the grain size reduction with doping. Fourier transform infrared spectroscopy confirmed the presence of metal-oxygen bond in pristine and doped NiO nanostructure as well as the presence of carbon containing groups. Scanning electron microscopy (SEM) indicated that the particle size decreased when NiO nanostructure was doped with copper. BET surface area was found to increase almost up to 43 m2/g for Cu doped NiO nanostructure/rGO composite. Current-voltage measurements were performed using two probe method. UV–Visible spectroscopic profiles showed the blue and red shift for Cu doped NiO nanostructure and Cu doped NiO Nanostructure/rGO composite respectively. Rate constant for Cu doped NiO nanostructure/rGO composite found to increase 4.4 times than pristine NiO nanostructure. 相似文献
69.
Few cities in Europe have a history as dramatic and tumultuous as that of the Serbian capital of Belgrade. The gracious “White City,” which rises spectacularly along the banks of the Danube and the Sava River, has been the site of wars, conquests and rapidly changing fortunes for much of its thousands-years long history. Belgrade suffered heavy destruction under both World Wars, and it has the unfortunate distinction of being the only European capital to be bombed at the end of the 20th century. Its modern history is marked by abrupt shifts in political status: from a capital of a relatively small nation-state, to a center of a larger and prosperous multi-national federation, to a capital of a nation-state once again. These shifts parallel the changing geopolitical position of Serbia/Yugoslavia in Europe. In this City Profile, I present the evolution of the built environment of Belgrade in five historic stages: ancient/medieval/Ottoman, early modern, communist, transitional, and contemporary. I show how each period left a distinct spatial imprint on Belgrade’s fabric. Finally, I discuss some contemporary challenges and opportunities in planning Belgrade’s future. 相似文献
70.
Traditional input indicators of research performance, such as research funding, number of active scientists, and international
collaborations, have been widely used to assess countries’ publication output. However, while publication in today’s English-only
research world requires sound research in readable English, English proficiency may be a problem for the productivity of non-native
English-speaking (NNES) countries. Data provided by the Brazilian National Research Council (CNPq) containing the academic
profile of 51,223 Brazilian researchers show a correlation between English proficiency and publication output. According to
our results, traditional input indicators may fall short of providing an accurate representation of the research performance
of NNES developing countries. 相似文献