Distribution of current density across the active area at various stoichiometry ratios using the JRC ZERO∇CELL single cell PEM fuel cell testing hardware

The performance of the PEM fuel cell directly depends on the partial pressure of provided reactants, namely hydrogen and oxygen. Since reactants are consumed in the fuel cell reaction, partial pressure of reactants decreases in the direction of reactants flow. This well-known mechanism makes the performance of the fuel cell dependent on the stoichiometry ratios of input reactants. The JRC ZERO∇CELL, a single cell PEM fuel cell testing setup, is developed to provide as much as possible uniform operating conditions at the 10cm2 active area specimen, hence giving uniform current density across the active area of the cell. To investigate what is the real gradient of current density across the active area for the JRC ZERO∇CELL at various reactant stoichiometry ratios, segmented bi-polar plates and current collectors are developed. This study presents experimental investigation of the current density distribution across the active area of the JRC ZERO∇CELL setup at range of reactant stoichiometry ratios from λ = 2 up to λ = 15. Current density gradients are considered along the gas flow as well as in the transverse direction. The experimental results show that the current density gradient across the active area, although dependant on the reactants stoichiometry ratios, is relatively small as compared with a wide range of investigated stoichiometry ratios.

Laser Additively Manufactured Iron-Based Biocomposite: Microstructure, Degradation, and In Vitro Cell Behavior

A too slow degradation of iron (Fe) limits its orthopedic application. In this study, calcium chloride (CaCl2) was incorporated into a Fe-based biocomposite fabricated by laser additive manufacturing, with an aim to accelerate the degradation. It was found that CaCl2 with strong water absorptivity improved the hydrophilicity of the Fe matrix and thereby promoted the invasion of corrosive solution. On the other hand, CaCl2 could rapidly dissolve once contacting the solution and release massive chloride ion. Interestingly, the local high concentration of chloride ion effectively destroyed the corrosion product layer due to its strong erosion ability. As a result, the corrosion product layer covered on the Fe/CaCl2 matrix exhibited an extremely porous structure, thus exhibiting a significantly reduced corrosion resistance. Besides, in vivo cell testing proved that the Fe/CaCl2 biocomposite also showed favorable cytocompatibility.

Testing of solid oxide cells at high current densities

Solid Oxide Cells (SOCs) have gained an increasing interest as electrochemical energy converters due to their high efficiency, fuel flexibility and ability of reversible fuel cell/electrolysis operation. During the development process as well as in quality assurance tests, the performance of single cells and cell stacks is commonly evaluated by means of current/voltage- (CV-) characteristics. Despite of the fact that the measurement of a CV-characteristic seems to be simple compared to more complex, dynamic methods as electrochemical impedance spectroscopy or current interrupt techniques, the resulting performance strongly depends on the test setup and the chosen operating conditions. In this paper, the impact of different single cell testing environments and operating conditions on the CV-characteristic of high performance cells is discussed. The influence of cell size, contacting and current collection, contact pressure, fuel flow rate and composition on the achievable cell performance is presented and limitations arising from the test bed and testing conditions will be pointed out. As today’s high performance cells are capable of delivering current densities of several ampere per cm2 a special emphasis will be laid on single cell testing in this current range.

Chemical Degradation of the La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Sm0.2O2−δ Interface during Sintering and Cell Operation

A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance.

Potential Combination of Kapok Leaf Extract (Ceiba pentandra G.) and Turmeric Extract (Curcuma domestica Va) as an Anticancer Compound

Combination of kapok leaf extract (Ceiba pertandra G.) and turmeric extract (Curcuma domestica Va.) was carried out to determine the potential of extracts in treating cancer with BSLT and murine cells P388. Cancer is a disease that is very feared because it’s difficult to cure, and even rarely causes death. The sample was extracted with methanol, the extract was mixed so that the mixture extract from the two samples was obtained. The results showed that in the BSLT test the mixed extract had a bioactivity against shrimp larvae with an LC50 value of 142.946 ppm. While in Leukemia P388 cell testing showed that the combination of mixed extracts had a cytotoxic effect on Leukemia P388 cancer cells with inhibitory concentration values of 54.34 ppm. This shows that the kapok leaf extract (Ceiba pentandra G.) and combination of turmeric extract (Curcuma domestica Va.) has potential and can be developed as an anticancer agent because it has an IC50 value that can inhibit murine P388 cell growth and LC50 value which can kill shrimp larvae Artemia salina L.

T-cell receptor sequencing identifies prior SARS-CoV-2 infection and correlates with neutralizing antibody titers and disease severity

Measuring the adaptive immune response to SARS-CoV-2 can enable the assessment of past infection as well as protective immunity and the risk of reinfection. While neutralizing antibody (nAb) titers are one measure of protection, such assays are challenging to perform at a large scale and the longevity of the SARS-CoV-2 nAb response is not fully understood. Here, we apply a T-cell receptor (TCR) sequencing assay that can be performed on a small volume standard blood sample to assess the adaptive T-cell response to SARS-CoV-2 infection. Samples were collected from a cohort of 302 individuals recovered from COVID-19 up to 6 months after infection. Previously published findings in this cohort showed that two commercially available SARS-CoV-2 serologic assays correlate well with nAb testing. We demonstrate that the magnitude of the SARS-CoV-2-specific T-cell response strongly correlates with nAb titer, as well as clinical indicators of disease severity including hospitalization, fever, or difficulty breathing. While the depth and breadth of the T-cell response declines during convalescence, the T-cell signal remains well above background with high sensitivity up to at least 6 months following initial infection. Compared to serology tests detecting binding antibodies to SARS-CoV-2 spike and nucleoprotein, the overall sensitivity of the TCR-based assay across the entire cohort and all timepoints was approximately 5% greater for identifying prior SARS-CoV-2 infection. Notably, the improved performance of T-cell testing compared to serology was most apparent in recovered individuals who were not hospitalized and were sampled beyond 150 days of their initial illness, suggesting that antibody testing may have reduced sensitivity in individuals who experienced less severe COVID-19 illness and at later timepoints. Finally, T-cell testing was able to identify SARS-CoV-2 infection in 68% (55/81) of convalescent samples having nAb titers below the lower limit of detection, as well as 37% (13/35) of samples testing negative by all three antibody assays. These results demonstrate the utility of a TCR-based assay as a scalable, reliable measure of past SARS-CoV-2 infection across a spectrum of disease severity. Additionally, the TCR repertoire may be useful as a surrogate for protective immunity with additive clinical value beyond serologic or nAb testing methods.

Does Vein-first Lobectomy Control Postoperative Circulating Tumor Cells in Lung Cancer?: a Retrospective Observational Study

Background: Vein-first dissecting lobectomy in lung cancer surgery is speculated to limit the amount of circulating tumor cells. We aimed to assess the clinical significance and prognostic impact of Vein-first dissecting lobectomy according to changes in circulating tumor cell status throughout the perioperative period.Methods: Among patients with pulmonary nodule who underwent surgery, we extracted and evaluated patients who underwent lobectomy for lung cancer and had underwent circulating tumor cell testing before and immediately after the completion of lobectomy. The primary evaluation item was the detection rate of postoperative circulating tumor cell according to the sequence of pulmonary vessel processing. The secondary evaluation items were the 2-year recurrence-free survival and overall survival rates according to the status of Vein-first dissecting lobectomy and postoperative circulating tumor cell. Results: Between June 2014 and June 2018, 302 patients with pulmonary nodule underwent surgery, among them we selected 86 patients who underwent lobectomy for lung cancer and had circulating tumor cell testing done before and immediately after the completion of lobectomy. The circulating tumor cell identification rates in the postoperative period were 54.4% (37/68) and 66.7% (12/18) (p=0.8) in vein-first dissecting lobectomy group and no-vein-first dissecting lobectomy group, respectively. The mean postoperative circulating tumor cell count was not significantly different between the vein-first dissecting lobectomy and no-vein-first dissecting lobectomy groups (3.0 ± 3.6 vs 3.2 ± 5.0, p=0.8). The 2-year recurrence-free survival and overall survival rates were also not significantly different. However, the presence of circulating tumor cell after surgery was a predictor of recurrence.Conclusions: Although the detection of circulating tumor cell after surgery is a predictor of cancer recurrence, no significant difference was observed in the status of postoperative circulating tumor cell s between vein-first dissecting lobectomy and no- vein-first dissecting lobectomy groups in lung cancer surgery.