Scalable and Cost-effective Barrier Layer Coating to Improve Stability and Performance of SOFC Cathode

Replacing the electronically conductive (LaSr)MnO3±δ (LSM) cathode in the LSM/yttrium- stabilized zirconia (YSZ) system with the mixed ion-electron conductive (MIEC) (LaSr)(CoFe)O3-δ (LSCF) will promote cathode performance in SOFCs significantly. However, it might be hindered by the reaction between YSZ and LSCF, producing some insulating phases, which lowers the cell performance. To address this issue, a dense barrier layer of doped ceria is always adopted between these two components to eliminate the reaction as well as to boost the cell performance. In this study, a scalable and cost-effective method, electrophoretic deposition (EPD), is used to realize the deposition of gadolinium doped ceria (GDC) on non-conductive YSZ substrate. The fundamental characteristics of EPD of GDC on YSZ and the mechanism are also systematically investigated. Highly compact GDC green layers are obtained by the EPD process in an ethanol-based suspension. GDC thin layers in a thickness range of 5-8 µm have been successfully densified at temperatures as low as 1300 oC and the adhesion between GDC and YSZ is excellent. Compared to a GDC barrier layer made by a conventional spin-coating method, the ohmic resistance of GDC made by EPD is lower. The deposition rate of GDC on PPy coated YSZ is slower than that on graphite at the same voltage. However, at constant current, the mass of GDC deposited per coulomb of charge is larger on the PPy-coated YSZ cathode. An H+ ion accumulation zone is formed near the PPy coated YSZ after applying the voltage. The thickness of this H+ ion accumulation zone increases at the beginning and then decreases. Finally, the ion accumulation zone is replaced by an ion depletion zone; the main reason contributing to the increasing resistance is the formation of an ion depletion zone. The absorbed H+ ions desorb from particles after deposition and then move through the porous deposit to the cathode to be reduced. The reduction of free H+ ions and absorbed H+ ions corresponds to the unavoidable side reaction and the deposition of GDC particles, respectively. Deposition efficiency, f, the percentage of electric charge associated with the reduction of H+ ions in the total charge, is introduced to reflect the competitive relationship between deposition and the side reactions. f decreases with the increase of current density. A dense GDC layer is successfully obtained by AC-EPD at 500 Hz after sintering at a relatively low temperature, e.g., 1250 oC, which is anticipated to eliminate the reaction between LSCF and YSZ. An optimum frequency of 500 Hz leads to the maximum deposition rate by balancing the suppression of bubble evolution and the acceleration of the particle migration. The deposit yield in a given time grows with the increase of voltage ratio and forward width percentage. In AC-EPD with negligible faradic current, the deposition rate of GDC particles is determined by both the transport process and the desorption process, wherein the latter process is irreversible. The deposit yield is monotonically controlled by the deposition time, suggesting the possibility of fabrication of GDC layer with tunable thickness. Dense and homogeneous GDC films have also been successfully prepared by AC-EPD in an aqueous suspension. The parameters influencing the quality of deposition films are thoroughly investigated and the optimal deposition conditions include the frequency of 1 kHz, forward width percentage of 50 % and a voltage ratio of 10/4. This work provides a facile approach to fabricating smooth GDC barrier layers with tunable thickness in an environmentally benign, rapid, versatile and low-cost manner, indicating its promise for SOFC and other applications

AFFECT, MOTIVATION, AND ENGAGEMENT IN THE CONTEXT OF MATHEMATICS EDUCATION: TESTING A DYNAMIC MODEL OF INTERACTIVE RELATIONSHIPS

The present study tested the interactive model of affect, motivation, and engagement (Linnenbrink, 2007) in mathematics education with a nationally representative sample. Self-efficacy, self-concept, and anxiety were indicators of pleasant and unpleasant affect. Intrinsic and extrinsic motivation were indicators of mastery and performance approach. Persistence and cognitive activation were indicators of behavioral and cognitive engagement. The 2012 Programme for International Student Assessment (PISA) supplied a sample of 4,978 students from the United States for structural equation modeling. The results indicated that PISA data overall supported the interactive model. Specifically, PISA data completely supported the specification of the relationship between motivation and affect, largely supported the specification of the relationship between affect and engagement, but failed to support the specification of the relationship between motivation and engagement. Finally, PISA data largely supported the specification of the mediation effects of affect on the relationship between motivation and engagement

Supply Chain Structure, Inventory Turnover, and Financial Performance: Evidence from Manufacturing Companies in China

Using data collected by the World Bank, we empirically investigate the relationship between Chinese manufacturers’ supply chain attributes, raw material and finished goods inventory turnover, and return on sales. Our findings indicate that location proximity, relationship continuity, and the relative power of the manufacturer over suppliers and customers have a significant impact on inventory performance, which in turn drives profitability. We especially focus on characteristics unique to China’s business environment. We find that Chinese manufacturing companies have relatively weak operational performance, and better operational performance is associated with closer distance, longer relationship with suppliers and customers, and relative power over suppliers. Unlike their counter parties in some developed countries, Chinese manufacturers’ profitability relies on both downstream and upstream inventory performance, with downstream inventory performance playing a somewhat more important role

Effect of wrapped Fibre on tenacity of viscose vortex yarn

Effect of wrapped fibre on tenacity of vortex yarn has been studied by spinning experiments, SEM observation and an ideal twisting model, which will help industry to predict and improve the yarn quality. The spinning results show that the changes in the wrapped fibres (including the number of wrapped fibre and the wrapping angle) determine the yarn tenacity. With the increase in nozzle pressure, the number of wrapped fibre increases significantly, the tenacity of the yarn increases, and the change in wrapping angle is just a little. On the other hand, with the increase in the nozzle orifice angle, the wrapping angle and the yarn tenacity increase, which shows a good agreement with the ideal twisting model results. Therefore, the tenacity of vortex yarn mainly depends on the number of wrapped fibre and the wrapping angle

Analysis of the Success of House of Cards

Two Thousand and Thirteen was a good year for Netflix. The first Netflix original programming, House of Cards entire first season, was launched on February 1, 2013. It allows subscribers to binge watch, frees them from the anxiety of waiting, and of course, becomes popular. More than that, high quality of the show fetched positive critics' reviews and nine Primetime Emmy Award nominations which is a first for online-only web television series (CNN, 2014). Its success led to the renewal of the third season. In the era of the convergence of traditional and new media, the change caught everyone's attention. Content providers acquired a new distribution channel. Media owners combine their resources. It makes combined the function of two or more devices and the new way to distribute content happen. Some of the critics and researchers deem Netflix is the future of television (Paskin, 2013). However, the famous House of Cards is not the only Netflix Original. In fact, there are 23 other Netflix original shows in the year of 2013 only. It seems to be the solution to extend the on-demand content selection, so that, Netflix would not be just a platform for customers to access and manage their entertainment. By investigating into Netflix, we may understand what made House of Cards stand out and how it influenced the future of streaming media.M.S., Television Management -- Drexel University, 201

What professional factors do teachers identify as stressful in an international school?

In this study, I aimed to identify the professional factors that cause teachers to feel stressed working in an international school in Italy and whether are those factors are related to the international context of the school. I carried out semi-structured interviews with six classroom teachers who currently work at the school. Five out of the six teachers reported that working in this international school was either mildly stressful or moderately stressful, with one teacher reporting that it is very stressful. The three main sources of stress identified were: the workload; time limitations; and the lack of resources. Teachers all revealed from their own teaching experience that if they feel stressed, it does affect them personally and professionally. Three teachers even described their experiences of near 'burnout' in their previous schools in the UK. Teachers also gave some productive suggestions for the school to help to prevent and reduce stress. These findings are mostly in line with those reported in previous research, whilst there are some differences according to the international school context

How Does Complement Affect Hematological Malignancies: From Basic Mechanisms to Clinical Application

Complement, as a central immune surveillance system, can be activated within seconds upon stimulation, thereby displaying multiple immune effector functions. However, in pathologic scenarios (like in tumor progression), activated complement can both display protective effects to control tumor development and passively promotes the tumor growth. Clinical investigations show that patients with several hematological malignancies often display abnormal level of specific complement components, which in turn modulates complement activation or deregulated cascade. In the past decades, complement-dependent cytotoxicity and complement-dependent cell-mediated phagocytosis were fully approved to display vital roles in monoclonal antibody-based immunotherapies, especially in therapies against hematological malignancies. However, tumor-mediated complement evasion presents a big challenge for such a therapy. This review aims to provide an integrative overview on the roles of the complement in tumor promotion, highlights complement mediated effects on antibody-based immunotherapy against distinct hematological tumors, hopefully provides a theoretical basis for the development of complement-based cancer targeted therapies

Molecular Dynamic Simulation of Diffusion in the Melt Pool in Laser Additive Alloying Process of Co-Ni-Cr-Mn-Fe High Entropy Alloy

High entropy alloys (HEAs) can be manufactured in many conventional ways, but it becomes difficult of fabricating heterogeneous materials and structures. Selective Laser Melting (SLM) method generally melts pure elemental powders or prefabricated alloy powders without alloying process. In-situ alloying in SLM, which is also called Laser Additive Alloying (LAA), using pure elemental powders becomes a promising method for creating HEA with heterogeneous structures. However, the effect of the diffusion of elements in the molten pool on the formation of HEA remains unclear. In this paper, the well-discussed Cantor HEA was studied in an in-situ alloying situation, where pure elemental powders (Co, Cr, Mn, Ni, Fe) distributed on a powder bed were irradiated by laser and were subsequently allowed to cool back to room temperature. The diffusion of specific elements, with respect to their original clusters, was tracked via Mean Square Displacement (MSD) as well as the final composition of key locations. Our model was verified by showing a good agreement with the overall average diffusion rates of each element in the Cantor HEA qualitatively in other works from literature. Results initially showed that as the energy density increases, better diffusion was observed through a pixel overlay analysis about the mixing of different elements. The best-case scenario of diffusion from the pixel overlay map indicated a strong presence of 3 to 4 elements after the laser scanning. Given the conditions in the MD simulation, there was no apparent segregation of elements during the alloying process. In addition, we also conducted a simulation by implementing a 0.03 nm/ps laser scanning in a meander 2-track scan in order to completely melt the powder bed. After cooling and equilibration, Polyhedral Template Analysis was applied to analyze the crystal structure of the solidified powder bed in the presence of increasing components. When the powders of Cantor HEA were alloyed using LAA approach, all elements experienced a complex diffusion behavior, elements like Cr also experienced a relatively rapid diffusion compared to other elements. Despite this, Cr only diffused for a short period and diffused minimally during the in-situ alloying process. The analysis of element-specific behavior, such as diffusion, can provide a framework for the LAA production of HEA. This MD study provides a detailed analysis about the effect of diffusion on the formation of HEA system if in-situ alloying is adopted, the findings of this study can be used to guide the material design and the appropriate parameters for manufacturing process of new HEAs. This study can also be extended to analyze the effect of diffusion on the thermomechanical properties of HEAs