3D microstructure characterization of polymer battery electrodes by statistical image analysis based on synchrotron X ray tomography

Polymer based batteries represent a promising concept for next generation energy storage due to their potentially higher power densities and smaller ecological footprint, compared to classical Li ion batteries. Since the microstructure of electrodes is a key factor for the performance of battery cells, a detailed understanding of this microstructure is essential for the improvement of manufacturing processes. In the present contribution, the 3D microstructure of electrodes for polymer based batteries is quantitatively characterized for the first time, where synchrotron X ray tomography is combined with statistical image analysis. In particular, 3D imaging is performed for two porous electrodes, which both consist of the redox active polymer PTMA as well as conductive additives, but differ regarding their binder materials. The focus is put on local heterogeneity of volume fractions of the constituents, surface area per unit volume of the polymer phase and the length of shortest transportation paths through both, polymer and binder additive phase. It is shown that using different binder materials leads to significant differences regarding the 3D electrode microstructures. In this way, statistical analysis of image data helps to gain further insight into the influence of manufacturing processes on electrode microstructures and thus, on the performance of battery cell

T cell adhesion and cytolysis of pancreatic cancer cells: a role for E-cadherin in immunotherapy?

Pancreatic cancer is an aggressive and potent disease, which is largely resistant to conventional forms of treatment. However, the discovery of antigens associated with pancreatic cancer cells has recently suggested the possibility that immunotherapy might become a specific and effective therapeutic option. T cells within many epithelia, including those of the pancreas, are known to express the αEβ7-integrin adhesion molecule, CD103. The only characterised ligand for CD103 is E-cadherin, an epithelial adhesion molecule which exhibits reduced expression in pancreatic cancer. In our study, CD103 was found to be expressed only by activated T cells following exposure to tumour necrosis factor beta 1, a factor produced by many cancer cells. Significantly, the expression of this integrin was restricted mainly to class I major histocompatibility complex-restricted CD8+ T cells. The human pancreatic cancer cell line Panc-1 was transfected with human E-cadherin in order to generate E-cadherin negative (wild type) and positive (transfected) sub-lines. Using a sensitive flow cytometric adhesion assay it was found that the expression of both CD103 (on T cells) and E-cadherin (on cancer cells) was essential for efficient adhesion of activated T cells to pancreatic cancer cells. This adhesion process was inhibited by the addition of antibodies specific for CD103, thereby demonstrating the importance of the CD103→E-cadherin interaction for T-cell adhesion. Using a 51Cr-release cytotoxicity assay it was found that CD103 expressing T cells lysed E-cadherin expressing Panc-1 target cells following T cell receptor stimulation; addition of antibodies specific for CD103 significantly reduced this lysis. Furthermore, absence of either CD103 from the T cells or E-cadherin expression from the cancer cells resulted in a significant reduction in cancer cell lysis. Therefore, potentially antigenic pancreatic cancer cells could evade a local anti-cancer immune response in vivo as a consequence of their loss of E-cadherin expression; this phenotypic change may also favour metastasis by reducing homotypic adhesion between adjacent cancer cells. We conclude that effective immunotherapy is likely to require upregulation of E-cadherin expression by pancreatic cancer cells or the development of cytotoxic immune cells that are less dependent on this adhesion molecule for efficient effecter function

Investigating the influence of the calendering process on the 3D microstructure of single layer and two layer cathodes in lithium ion batteries using synchrotron tomography

Further improvement of the performance of lithium ion batteries is a central goal in state of the art battery research to satisfy the permanently growing demands. This can be achieved by optimizing the 3D microstructure of the electrodes, which in turn depends on the material composition used as well as on the corresponding production parameters. Since the calendering process of electrodes has a significant impact on their microstructure, the goal of this paper is to further deepen the understanding of how varying the compaction load changes the microstructure of lithium ion battery cathodes. For this purpose, three different sample sets are analyzed and compared to each other, using image data gained by synchrotron tomography. More precisely, we consider differently compacted thin and thick cathodes as well as a set of porosity graded two layer cathode samples. A phase based as well as a particle based segmentation of the tomographic image data is performed to allow for an extensive morphological analysis of the cathode samples, where, among others, mean geodesic tortuosity of the pore space and particle connectivity are considered to quantify changes of the 3D microstructure. Furthermore, for the two layer sample set, a special focus is put on microstructural changes of both layers and the interface between the

Stochastic 3D microstructure modeling of anodes in lithium ion batteries with a particular focus on local heterogeneity

Lithium ion batteries can be considered as one of the most important energy storing devices. To satisfy the rapidly growing demand for higher energy densities, as for example required by tomotive applications, the optimization of the electrode morphology is an important goal in battery research since it is well known that the 3D microstructure of anodes and cathodes has a significant impact on the resulting performance of the battery. A promising approach is called virtual materials testing, where stochastic 3D microstructure models are used to generate a wide range of virtual but realistic electrode morphologies as structural input for spatially resolved numerical simulations of effective electrochemical properties. This beneficial combination allows to derive microstructure property relationships just at the cost of computer simulations. The present paper introduces a novel parametric stochastic 3D microstructure model based on random fields that is calibrated to tomographic image data of six graphite anodes. The model is validated by comparing geometrical characteristics and effective tortuosity, which significantly influences the electrochemical behaviour of battery electrodes, computed for tomographic and simulated image data, respectively. A particular focus is put on local heterogeneity, which is quantitatively accessed by computing local distributions of certain microstructure dependent descriptor

Unveiling the Impact of Cross Linking Redox Active Polymers on Their Electrochemical Behavior by 3D Imaging and Statistical Microstructure Analysis

Polymer based batteries offer potentially higher power densities and a smaller ecological footprint compared with state of the art lithium ion batteries comprising inorganic active materials. However, in order to benefit from these potential advantages, further research to find suitable material compositions is required. In the present paper, we compare two different electrode composites of poly 2,2,6,6 tetramethylpiperidinyloxy 4 yl methacrylate PTMA and CMK 8, one produced with and one without cross linking the PTMA. The influence of both approaches on the corresponding electrodes is comparatively investigated using electrochemical measurements and statistical 3D microstructure analysis based on synchrotron X ray tomography. A particular focus is put on the local heterogeneity in the coating and how the cross linking influences the interaction between PTMA and CMK 8. It is shown that cross linked PTMA compared to its non cross linked counterpart exhibits a more heterogeneous microstructure and, furthermore, leads to better surface coverage of CMK 8, larger pores, and shorter transportation pathways through the latter. These changes improve the electrochemical properties of the electrod

Understanding clinical risk decision making regarding development of depression during interferon-alpha treatment for hepatitis-C: A qualitative interview study

Background: Hepatitis C virus (HCV) affects 170 million worldwide. Currently, around 30% of patients receiving interferon-alpha (IFN-α) treatment for HCV experience clinically significant depression. Effective and timely detection of depression is crucial to ensuring appropriate treatment and support. However, little is known about how clinical nurse specialists identify patients at risk of developing interferon-alpha-induced depression, and monitor those receiving antiviral treatment for the occurrence of depression.Author has checked copyright11/11/2013. SB

Effector T lymphocyte subsets in human pancreatic cancer: detection of CD8+ CD18+ cells and CD8+ CD103+ cells by multi-epitope imaging

Pancreatic cancer is characterized by an increasing incidence and an extremely poor prognosis. It is resistant to most of the conventional treatment modalities. Histomorphologically, it presents with a strong desmoplastic reaction around cancer cells, and lymphocytes are typically localized as aggregates in the fibrotic interstitial tissue. Using the method of multi-epitope imaging with fluorochrome-tagged specific MoAbs which allows the simultaneous localization and characterization of T cells in tissues, we studied phenotypes and distribution of tumour-infiltrating lymphocytes (TIL) in pancreatic cancer. CD3+ T cells comprised up to 90% of the tumour-infiltrating cells which were either CD4+ or CD8+, most of them being memory cells (CD45RO+). In decreasing order of frequency, T lymphocytes carried the markers for CD45RO, CD18, CD103 and TCR γδ. Very few natural killer cells (CD56+) were observed. Twenty percent of CD8+ were labelled with CD103. These CD8+ CD103+ T cells, analogous to the gut intraepithelial lymphocytes (IEL), were found in the fibrous interstitial tissue. Furthermore, an inverse correlation was found between the expression of CD18, the β2-integrin, which mediates adhesion of activated lymphocytes, and CD45RO in the CD8+ subset of TIL (P = 0.046). In conclusion, phenotyping of T lymphocytes in pancreatic cancer raises the possibility that pancreatic cancer cells develop several strategies to escape the T cell-induced cytolysis by (i) the aggregation of cytotoxic CD8+ CD103+ T cells in the fibrous tissue distant from the tumour cells, and (ii) the presence of CD18-bearing cells which lack the expression of the activation marker CD45RO