Experimental observations of the co-sintering of porous triple-layer SOFCs including curvature evolution

Triple-layer co-sintering of SOFCs results in an improved production process via reduced time and effort. Understanding the sintering shrinkage behaviour of each porous layer during the co-sintering process leads to the minimisation of mismatched stresses along with avoidance of severe warping and cracking. In multilayer structure, sintering behaviour is mainly characterised by the in-plane properties rather than the thickness properties. The induced in-plane stresses contribute to curvature evolution in the structure, which can be utilised in the design of a SOFC

Fabrication of three-dimensional wavy single chamber solid oxide fuel cell by in situ observation of curvature evolution

This study presents a fabrication process via experimental observations for curved porous multi-layer structures during co-sintering. Analysis of curvature evolution using in-situ monitoring of the structure was used in the design of a curved multi-layer structure. Materials used are NiO/gadolinium-doped cerium oxide (NiO/CGO) for anode; CGO for electrolyte; and lanthanum strontium manganite (LSCF) for cathode. In-situ observation, to monitor the shrinkage of each material and the evolution of the bi- and triple-layer structures, was performed using a long focus microscope (Infinity K-2). The results contribute to develop a novel design curved three dimensional multi-layer structures during co-sintering

Multi-junction thermocouple array for in-situ temperature monitoring of SOFC: simulation

Novel multi-junction thermocouple architecture was developed and simulated to in-situ monitor the temperature distribution over a Solid Oxide Fuel Cell (SOFC). This thermocouple architecture requires only {N+1} number of wires for N number of independent temperature measuring points. Therefore, N+1 architecture can independently measure temperature at multiple points simultaneously with much less number of wires than a set of thermocouples require for the same number of independent temperature measurements. Requiring less number of external wires is a distinct advantage, particularly, in constrained environments such as those within SOFC stacks. A thermocouple array having 4 independent temperature measuring points with 5 thermo-elements was simulated in MATLAB. Alumel (Ni:Al:Mn:Si – 95:2:2:1 wt) and Chromel (Ni:Cr – 90:10 wt) were chosen as thermo-element materials because of their wide applicability in the industry as K-type thermocouples. The junctions were considered to be spot welded. Three sets of simulations were performed to investigate two aspects: validation of the multi-junction thermocouple concept and investigation of the effect of the heat affected zone created in spot welding to the temperature measurement. Simulation code generates random temperature values for each junction within a pre-defined range. Temperatures at the boundaries of heat affected zones were also generated randomly according to a pre-defined criterion. The change of Seebeck coefficients within the heat affected zone was set as a percentage change of their corresponding materials Seebeck coefficient. The temperature gradient induced emf values for each sensing point were calculated from Seebeck coefficients. The calculated emf was then mapped back to temperature using ASTM approved inverse conversion function. These mapped temperatures were then compared with the set temperatures for each junction and they were in very good agreement

Thin-film multi-junction thermocouple array for in-situ temperature monitoring of SOFC

Thin-film multi-junction thermocouple array for in-situ temperature monitoring of SOF

Cell integrated thin-film multi-junction thermocouple array for in-situ temperature monitoring of Solid Oxide Fuel Cells

A thin-film multi-junction thermocouple array was developed and tested for multi-point simultaneous temperature measurements from an operating SOFC stack. The array requires only {N+1} number of wires/ thermo-elements for N number of independent temperature measuring points. Hence, it requires less number of lead wires than any available contact-temperature sensors require for the same number of measurements. Because the multi-junction thermocouple array operates on the same principle of a conventional thermocouple, the Seebeck effect, it shares all the merits of a thermocouple. A thin-film multi-junction thermocouple array was sputter deposited on the cathode of a SOFC test cell and tested and evaluated up to 10500C from 200C. Temperature measured from the thermocouple array was compared with that from a commercial thermocouple placed adjacent to it during the test; they were in very good agreement within the entire temperature range that a SOFC stack generally operates

Symbolic Violence and Social Control in the Post-Total Institution Era

Subsequent to the passage of the Community Mental Health Act in 1963, the Total Institutions described by Goffman have for the most part disappeared. Nonetheless, many writers charge that social control is still the primary function of mental health programs, even those that are identified as community-based. The new methods of control have not received widespread attention. In community-based programs control is operationalized in the form of symbolic violence. This paper examines the various factors that contribute to this style of violence

Fabrication and evaluation of a novel wavy Single Chamber Solid Oxide Fuel Cell via in-situ monitoring of curvature evolution

Wavy type Single Chamber Solid Oxide Fuel Cells (SC-SOFCs) are beneficial for improved triple phase boundary conditions contributing to higher performance, compared with planar type SC-SOFCs of the same diameter. This study presents a fabrication process for wavy-type, cathode-supported SC-SOFCs with a single fabrication step via co-sintering of a triple-layer structure consisting of NiO/CGO-CGO-LSCF, with a thickness ratio of 1:3:9 respectively. Curvature evolution occurs due to different sintering behaviour of each layer during the co-sintering process. In-situ observation of each layer during the co-sintering process allows for minimisation of mismatched stresses to avoid unnecessary warping and cracking. Bilayers, consisting of NiO/CGO-CGO and CGO-LSCF, are co-sintered at 1200°C. In-situ observation, to monitor the shrinkage of each material and the curvature evolution of the structures, is performed using a long focus microscope (Infinity K-2). Monitoring curvature behaviour in real time minimised the development of undesired curvature in the triple-layer structure. Performance testing of wavy cell is carried out in a methane-air mixture (CH4:O2 =1:1). The wavy SC-SOFC generated 0.39 V and 9.7 mWcm-2 at 600°C, which produced 260% and 540% increments in OCV and in maximum power density, respectively, over the planar SC-SOFC under the same operational conditions

Lamellar keratoplasty using position-guided surgical needle and M-mode optical coherence tomography

Deep anterior lamellar keratoplasty (DALK) is an emerging surgical technique for the restoration of corneal clarity and vision acuity. The big-bubble technique in DALK surgery is the most essential procedure that includes the air injection through a thin syringe needle to separate the dysfunctional region of the cornea. Even though DALK is a well-known transplant method, it is still challenged to manipulate the needle inside the cornea under the surgical microscope, which varies its surgical yield. Here, we introduce the DALK protocol based on the position-guided needle and M-mode optical coherence tomography (OCT). Depth-resolved 26-gage needle was specially designed, fabricated by the stepwise transitional core fiber, and integrated with the swept source OCT system. Since our device is feasible to provide both the position information inside the cornea as well as air injection, it enables the accurate management of bubble formation during DALK. Our results show that real-time feedback of needle end position was intuitionally visualized and fast enough to adjust the location of the needle. Through our research, we realized that position-guided needle combined with M-mode OCT is a very efficient and promising surgical tool, which also to enhance the accuracy and stability of DALK

Antiretroviral Genotypic Resistance Mutations in HIV-1 Infected Korean Patients with Virologic Failure

Resistance assays are useful in guiding decisions for patients experiencing virologic failure (VF) during highly-active antiretroviral therapy (HAART). We investigated antiretroviral resistance mutations in 41 Korean human immunodeficiency virus type 1 (HIV-1) infected patients with VF and observed immunologic/virologic response 6 months after HAART regimen change. Mean HAART duration prior to resistance assay was 45.3±27.5 months and commonly prescribed HAART regimens were zidovudine/lamivudine/nelfinavir (22.0%) and zidovudine/lamivudine/efavirenz (19.5%). Forty patients (97.6%) revealed intermediate to high-level resistance to equal or more than 2 antiretroviral drugs among prescribed HAART regimen. M184V/I mutation was observed in 36 patients (87.7%) followed by T215Y/F (41.5%) and M46I/L (34%). Six months after resistance assay and HAART regimen change, median CD4+ T cell count increased from 168 cells/µL (interquartile range [IQR], 62-253) to 276 cells/µL (IQR, 153-381) and log viral load decreased from 4.65 copies/mL (IQR, 4.18-5.00) to 1.91 copies/mL (IQR, 1.10-3.60) (P<0.001 for both values). The number of patients who accomplished viral load <400 copies/mL was 26 (63.4%) at 6 months follow-up. In conclusion, many Korean HIV-1 infected patients with VF are harboring strains with multiple resistance mutations and immunologic/virologic parameters are improved significantly after genotypic resistance assay and HAART regimen change