The correlation between the capacity fade of LiFePO4 batteries and cycle life

A new model is developed by fitting the capacity of LiFePO$_4$ batteries, which can be used to investigate the relationship between capacity fade, state of health (SoH), electrochemical reactions and the number of cycles. The equation for the proposed model based on modified Thevenin circuit, Butler-Volmer kinetics and regression analysis consists of a constant term, a sine-exponential term and an exponential term. The constant term represents the rated capacity of a battery, while the sine-exponential term represents the variation in capacity in the active status and the exponential term represents the variation in capacity in the stable status. The model is divided into two parts. The first part is represented by the sine-exponential term, responsive to the activation of electrolyte and electrodes in the first 180 cycles; the second part can be described by the exponential term, estimating the capacity from cycle 180 to cycle 2000. In addition, the comparison between the model and mean absolute percentage error (mape) is able to predict the serious decay of capacity. The MAPE is only 0.47% for the tested battery. The proposed model also successfully estimates the capacity of a tested battery where the number of cycles is 2000 with the error of 0.90%. The results mean that the model is able to closely describe the correlation between capacity and the cycle numbers. References M. Zhao, G. Huang, W. Zhang, H. Zhang and X. Song, Electrochemical behaviors of limn1-xfexpo4$/$c cathode materials in an aqueous electrolyte with/without dissolved oxygen, Energy and Fuels 27 (2013), 2:1162-1167. doi:10.1021/ef301893b Y.-C. Wang, F.-M. Ni and T.-L. Lee, Hybrid modulation of bidirectional three-phase dual-active-bridge dc converters for electric vehicles, Energies 9 (2016), no. 7, 492. doi:10.3390/en9070492 A. H. N. Galapitage and P. Pudney, Scheduling electric vehicles with shared charging stations, ANZIAM Journal 57 (2016), 208. doi:10.21914/anziamj.v57i0.10443 T. Zhu, H. T. Min, Y. B. Yu, Z. M. Zhao, T. Xu, Y. Chen, X. Y. Li and C. Zhang, An optimized energy management strategy for preheating vehicle-mounted li-ion batteries at subzero temperatures, Energies 10 (2017), no. 2. doi:24310.3390/en10020243 K. M. Tsang and W. L. Chan, State of health detection for lithium ion batteries in photovoltaic system, Energ Convers Manage 65 (2013), 7-12. doi:10.1016/j.enconman.2012.07.006 Z. Rao, S. Wang, M. Wu, Z. Lin and F. Li, Experimental investigation on thermal management of electric vehicle battery with heat pipe, Energ Convers Manage 65 (2013), 92-97. doi:0.1016/j.enconman.2012.08.014 A. Nikolian, Y. Firouz, R. Gopalakrishnan, J.-M. Timmermans, N. Omar, P. van den Bossche and J. van Mierlo, Lithium ion batteries-development of advanced electrical equivalent circuit models for nickel manganese cobalt lithium-ion, Energies 9 (2016), no. 5, 360. doi:10.3390/en9050360 Z. Gao, C. Chin, W. Woo and J. Jia, Integrated equivalent circuit and thermal model for simulation of temperature-dependent lifepo_4 battery in actual embedded application, Energies 10 (2017), no. 1, 85. doi:10.3390/en10010085 S.-Y. Lee, W.-L. Chiu, Y.-S. Liao, K.-Y. Lee, J.-H. Chen, H.-J. Lin and K. Li, Modified empirical fitting of the discharge behavior of lifepo_4 batteries under various conditions, ANZIAM Journal textbf55 (2014), 368. doi:10.21914/anziamj.v55i0.8182 C.-Y. Chung, K.-Y. Lee, T.-J. Kuo, Z.-Y. Lin, S.-D. Wu, C. Fu, Mathematical fitting for the variation in capacity of lithium iron phosphate batteries corresponding to cycles, ANZIAM Journal 57 (2016), 291. doi:10.21914/anziamj.v57i0.10436 T. Zahid and W. Li, A comparative study based on the least square parameter identification method for state of charge estimation of a lifepo_4 battery pack using three model-based algorithms for electric vehicles, Energies 9 (2016), no. 9, 720. doi:10.3390/en9090720 T. Sasaki, Y. Ukyo and P. Novak, Memory effect in a lithium-ion battery, Nat Mater 12 (2013), no. 6, 569-575. doi:10.1038/nmat3623 B. R. Tiwari and M. M. Ghangrekar, Enhancing electrogenesis by pretreatment of mixed anaerobic sludge to be used as inoculum in microbial fuel cells, Energy $and$ Fuels 29 (2015), no. 5, 3518-3524. doi:10.1021/ef5028197 P. Bai and M. Z. Bazant, Charge transfer kinetics at the solid-solid interface in porous electrodes, Nat Commun 5 (2014), 3585. doi:10.1021/ef990039t A. Eddahech, O. Briat and J.-M. Vinassa, Determination of lithium-ion battery state-of-health based on constant-voltage charge phase, Journal of Power Sources 258 (2014), 218-227. doi:10.1016/j.jpowsour.2014.02.020 R. Castaing, Y. Reynier, N. Dupre, D. Schleich, S. J. S. Larbi, D. Guyomard and P. Moreau Degradation diagnosis of aged li4ti5012-lifepo_4 batteries, Journal of Power Sources 267 (2014), 744-752. doi:10.1016/jpowsour.2014.06.002 H. Bulter, F. Peters, J. Schwenzel and G. Wittstock, In situ quantification of the swelling of graphite composite electrodes by scanning electrochemical microscopy, J Electrochem Soc 163 (2016), no. 2, A27-A34. doi:10.1149/2.1061514je

Induced pluripotent stem cells and regenerative medicine

AbstractStem cells, a special subset of cells derived from embryo or adult tissues, are known to present the characteristics of self-renewal, multiple lineages of differentiation, high plastic capability, and long-term maintenance. Recent reports have further suggested that neural stem cells (NSCs) derived from the adult hippocampal and subventricular regions possess the utilizing potential to develop the transplantation strategies and to screen the candidate agents for neurogenesis, neuroprotection, and neuroplasticity in neurodegenerative diseases. In this article, we review the roles of NSCs and other stem cells in neuroprotective and neurorestorative therapies for neurological and psychiatric diseases. We show the evidences that NSCs play the key roles involved in the pathogenesis of several neurodegenerative disorders, including depression, stroke, and Parkinson’s disease. Moreover, the potential and possible utilities of induced pluripotent stem cells, reprogramming from adult fibroblasts with ectopic expression of four embryonic genes, are also reviewed and further discussed. An understanding of the biophysiology of stem cells could help us elucidate the pathogenicity and develop new treatments for neurodegenerative disorders. In contrast to cell transplantation therapies, the application of stem cells can further provide a platform for drug discovery and small molecular testing, including Chinese herbal medicines. In addition, the high-throughput stem cell-based systems can be used to elucidate the mechanisms of neuroprotective candidates in translation medical research for neurodegenerative diseases

Capturing Cognitive Fingerprints from Keystroke Dynamics

Conventional authentication systems identify a user only at the entry point. Keystroke dynamics can continuously authenticate users by their typing rhythms without extra devices. This article presents a new feature called cognitive typing rhythm (CTR) to continuously verify the identities of computer users. Two machine techniques, SVM and KRR, have been developed for the system. The best results from experiments conducted with 1,977 users show a false-rejection rate of 0.7 percent and a false-acceptance rate of 5.5 percent. CTR therefore constitutes a cognitive fingerprint for continuous. Its effectiveness has been verified through a large-scale dataset. This article is part of a special issue on security

Genomic Signatures of Human versus Avian Influenza A Viruses

Fifty-two species-associated amino acid residues were found between human and avian influenza viruses

Photothermal responsivity of van der Waals material-based nanomechanical resonators

Nanomechanical resonators made from van der Waals materials (vdW NMRs) provide a new tool for sensing absorbed laser power. The photothermal response of vdW NMRs, quantified from the resonant frequency shifts induced by optical absorption, is enhanced when incorporated in a Fabry-Perot (FP) interferometer. Along with the enhancement comes the dependence of the photothermal response on NMR displacement, which lacks investigation. Here, we address the knowledge gap by studying electromotively driven niobium diselenide drumheads fabricated on highly reflective substrates. We use a FP-mediated absorptive heating model to explain the measured variations of the photothermal response. The model predicts a higher magnitude and tuning range of photothermal responses on few-layer and monolayer NbSe$_{2}$ drumheads, which outperform other clamped vdW drum-type NMRs at a laser wavelength of $532\,$nm. Further analysis of the model shows that both the magnitude and tuning range of NbSe$_{2}$ drumheads scale with thickness, establishing a displacement-based framework for building bolometers using FP-mediated vdW NMRs.Comment: 7 pages, 4 figure

Multiple Lineages of Human Breast Cancer Stem/Progenitor Cells Identified by Profiling with Stem Cell Markers

Heterogeneity of cancer stem/progenitor cells that give rise to different forms of cancer has been well demonstrated for leukemia. However, this fundamental concept has yet to be established for solid tumors including breast cancer. In this communication, we analyzed solid tumor cancer stem cell markers in human breast cancer cell lines and primary specimens using flow cytometry. The stem/progenitor cell properties of different marker expressing-cell populations were further assessed by in vitro soft agar colony formation assay and the ability to form tumors in NOD/SCID mice. We found that the expression of stem cell markers varied greatly among breast cancer cell lines. In MDA-MB-231 cells, PROCR and ESA, instead of the widely used breast cancer stem cell markers CD44+/CD24-/low and ALDH, could be used to highly enrich cancer stem/progenitor cell populations which exhibited the ability to self renew and divide asymmetrically. Furthermore, the PROCR+/ESA+ cells expressed epithelial-mesenchymal transition markers. PROCR could also be used to enrich cells with colony forming ability from MB-361 cells. Moreover, consistent with the marker profiling using cell lines, the expression of stem cell markers differed greatly among primary tumors. There was an association between metastasis status and a high prevalence of certain markers including CD44+/CD24−/low, ESA+, CD133+, CXCR4+ and PROCR+ in primary tumor cells. Taken together, these results suggest that similar to leukemia, several stem/progenitor cell-like subpopulations can exist in breast cancer

Fabry-Perot Interferometric Calibration of 2D Nanomechanical Plate Resonators

Displacement calibration of nanomechanical plate resonators presents a challenging task. Large nanomechanical resonator thickness reduces the amplitude of the resonator motion due to its increased spring constant and mass, and its unique reflectance. Here, we show that the plate thickness, resonator gap height, and motional amplitude of circular and elliptical drum resonators, can be determined in-situ by exploiting the fundamental interference phenomenon in Fabry-Perot cavities. The proposed calibration scheme uses optical contrasts to uncover thickness and spacer height profiles, and reuse the results to convert the photodetector signal to the displacement of drumheads that are electromotively driven in their linear regime. Calibrated frequency response and spatial mode maps enable extraction of the modal radius, effective mass, effective driving force, and Young's elastic modulus of the drumhead material. This scheme is applicable to any configuration of Fabry-Perot cavities, including plate and membrane resonators