The solid–electrolyte interphase (SEI) is well-known to provide critical protection between the strongly reducing negative electrode and the organic electrolytes of nonaqueous batteries. Batteries ...with a poorly passivating SEI will suffer from rapid capacity fade and short lifetimes. Despite its importance and extensive study of its structure and composition, the mechanism of SEI passivation remains poorly understood. In this work, we demonstrate using electrochemical collector-generator measurements that the SEI is chemically selective in its passivation and propose a model based on catalytic active sites to explain its performance. Electrochemically interrogating the SEI with functionalized ferrocene mediators shows that the through-film mediator reduction is much more sensitive to mediator functional group than size, indicating preferential partitioning into the organic SEI layer. Additional experiments with controlled electrode crosstalk show that incorporation of dissolved transition metals increases both the density and the activity of active sites within the SEI. We conclude that the inner, inorganic layer is responsible for preventing charge transfer through the SEI while the outer, organic layer is minimally important. Our model reconciles contradictory observations from the literature and identifies the most important components of a functional battery interface.
Electrode cross-talk in Li-ion batteries refers to side reactions in which soluble products are generated at one electrode and consumed or further reacted at the other electrode. While these ...reactions impact battery lifetime directly, they perhaps have even greater consequence for battery management systems and state-of-health prediction. In this work, we review the current literature on cross-talk mechanisms, classify various reactions as firmly detrimental or beneficial to cell lifetime, and identify future scientific challenges in the area.
Climate change is a well-documented driver of both wildlife extinction and disease emergence, but the negative impacts of climate change on parasite diversity are undocumented. We compiled the most ...comprehensive spatially explicit data set available for parasites, projected range shifts in a changing climate, and estimated extinction rates for eight major parasite clades. On the basis of 53,133 occurrences capturing the geographic ranges of 457 parasite species, conservative model projections suggest that 5 to 10% of these species are committed to extinction by 2070 from climate-driven habitat loss alone. We find no evidence that parasites with zoonotic potential have a significantly higher potential to gain range in a changing climate, but we do find that ectoparasites (especially ticks) fare disproportionately worse than endoparasites. Accounting for host-driven coextinctions, models predict that up to 30% of parasitic worms are committed to extinction, driven by a combination of direct and indirect pressures. Despite high local extinction rates, parasite richness could still increase by an order of magnitude in some places, because species successfully tracking climate change invade temperate ecosystems and replace native species with unpredictable ecological consequences.
Complex side reactions drive capacity fade in modern Li-ion batteries and are a key factor in achieving extended battery lifetimes. Unfortunately, the interconnected nature of the reaction pathways ...means that optimizing one aspect of performance can result in a shift between benign and detrimental side reactions, and that simple Coulombic efficiency is unable to capture these differences. Because batteries are ultimately chemical reactors, reaction engineering principles can provide a suitable framework for understanding. The electrocatalytic systems of Li-O2 batteries and electrochemical CO2 reduction demonstrate both the importance of quantifying reaction selectivity and the key role that reactor geometry plays in this process. Recent findings from these fields suggest that battery side reactions should also be studied in reactors that have been optimized for analytics. In this reaction engineering context, we discuss the advantages and disadvantages of existing analytical tools and present pathways for designing new reactors that can directly evaluate Li-ion battery reaction selectivity. Quantification of selectivity and reaction parameters can direct materials design and improve lifetime prediction.
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•A Li inventory model demonstrates complexity of battery capacity fade prediction•Electrocatalysis-inspired methods for studying battery side reactions are explored•Novel reactor designs for improved battery analytics are proposed
Extending the lifetime of non-aqueous batteries, particularly Li-ion, is necessary to reduce large-scale energy storage costs and to mitigate the environmental concerns of battery disposal and recycling. Better understanding of the complex side reaction networks is necessary for improved lifetime. This perspective proposes that considering battery interfaces in the context of catalytic selectivity may provide a powerful approach to this problem. Extracting meaningful measurements of reaction selectivity requires detailed attention to reactant and product transport, as illustrated by recent findings in aqueous electrocatalysis. Ultimately, new reactor designs that control interelectrode communication while maintaining a realistic battery environment must be developed to measure reaction rates directly. This knowledge in turn could enable physics-based predictive models of battery lifetime.
Longer lifetime will improve the economic and environmental costs of Li-ion batteries. Predicting and controlling lifetime requires better understanding of chemical side reactions. Here, we argue that battery side reactions are essentially a problem of catalytic selectivity. In this reaction engineering context, we discuss the advantages and disadvantages of existing analytical tools and present pathways for designing new reactors that can directly evaluate Li-ion battery reaction selectivity.
Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome characterized by bilateral vestibular schwannomas (VS) which often result in deafness despite aggressive management. Meningiomas, ...ependymomas, and other cranial nerve and peripheral schwannomas are also commonly found in NF2 and collectively lead to major neurologic morbidity and mortality. Traditionally, the overall survival rate in patients with NF2 is estimated to be 38% at 20 years from diagnosis. Hence, there is a desperate need for new, effective therapies. Recent progress in understanding the molecular basis of NF2 related tumors has aided in the identification of potential therapeutic targets and emerging clinical therapies. In June 2010, representatives of the international NF2 research and clinical community convened under the leadership of Drs. D. Gareth Evans (University of Manchester) and Marco Giovannini (House Research Institute) to review the state of NF2 treatment and clinical trials. This manuscript summarizes the expert opinions about current treatments for NF2 associated tumors and recommendations for advancing therapies emerging from that meeting. The development of effective therapies for NF2 associated tumors has the potential for significant clinical advancement not only for patients with NF2 but for thousands of neuro-oncology patients afflicted with these tumors.
Cardiovascular disease remains the leading cause of morbidity and mortality in the United States and other developed countries, and is fast growing in developing countries, particularly as life ...expectancy in all parts of the world increases. Current recommendations for the prevention of cardiovascular disease issued jointly from the American Academy of Cardiology and American Heart Association emphasize that lifestyle modification should be incorporated into any treatment plan, including those on statin drugs. However, there is a dearth of data on the interaction between diet and statins with respect to additive, complementary or antagonistic effects. This review collates the available data on the interaction of statins and dietary patterns, cognition, genetics and individual nutrients, including vitamin D, niacin, omega-3 fatty acids, fiber, phytochemicals (polyphenols and stanols) and alcohol. Of note, although the available data is summarized, the scope is limited, conflicting and disparate. In some cases it is likely there is unrecognized synergism. Virtually no data are available describing the interactions of statins with dietary components or dietary pattern in subgroups of the population, particularly those who may benefit most were positive effects identified. Hence, it is virtually impossible to draw any firm conclusions at this time. Nevertheless, this area is important because were the effects of statins and diet additive or synergistic harnessing the effect could potentially lead to the use of a lower intensity statin or dose.
The development of anticancer therapies that target the angiogenic process is an area of major growth in oncology. A method of noninvasively measuring tumor vascular endothelial growth factor (VEGF) ...in vivo could provide important efficacy information for VEGF-dependent antiangiogenic agents and the role of VEGF in cancer biology. We have developed a novel radiotracer for use with positron emission tomography (PET) that enables noninvasive imaging of VEGF. This radiotracer comprises an IgG1 monoclonal antibody, known as VG76e, that binds to human VEGF, labeled with a positron-emitting radionuclide, iodine-124 ((124)I-SHPP-VG76e). Three radiolabeling strategies were evaluated to synthesize the radiotracer with optimal radiochemical yield, purity, and immunoreactivity. To evaluate the pharmacokinetics and VEGF-specific localization of (124)I-SHPP-VG76e, two subclones of the HT1080 human fibrosarcoma selected on the basis of differing VEGF production (26.6 and 1/3C, the former producing 2-4-fold more in vitro) were established in culture and grown as solid tumor xenografts in immune-deficient mice. A single i.v. injection of the radiotracer into tumor-bearing mice revealed a time dependent and specific localization of (125)I-SHPP-VG76e to the tumor tissue. Three validation studies established the VEGF specificity and potential for use of (124)I-SHPP-VG76e in vivo: (a) uptake of (125)I-SHPP-VG76e was 1.8-fold higher in HT1080-26.6 compared with HT1080-1/3C tumors (P < 0.05); (b) uptake of (125)I-SHPP-VG76e in HT1080-26.6 tumors was specifically blocked by prior administration of excess unlabeled VG76e (P < 0.05); and (c) tumor uptake of the IgG1, (125)I-SHPP-CIP5, which has a similar molecular weight as (125)I-SHPP-VG76e but does not recognize VEGF, was the same for both HT1080-26.6 and HT1080-1/3C (P > 0.05). Other than tumor localization, (125)I-SHPP-VG76e was present in urine and blood and to a lesser extent in heart, lungs, liver, kidney, and spleen. Whole-animal PET imaging studies revealed a high tumor-to-background contrast and also revealed (124)I-SHPP-VG76e distributions in the major organs. These studies support further development of (124)I-SHPP-VG76e as a radiotracer for measuring tumor levels of VEGF in humans.
Organic radical cations are important intermediates in a wide variety of chemical processes. To date, significant progress has been made to improve the stability of these charged materials for use in ...electrochemical energy storage applications, especially in redox flow batteries. Here, we report the synthesis and isolation of four radical cation salts of N-(2-(2-methoxyethoxy)ethyl)phenothiazine (MEEPT), synthesizing MEEPT-X where X is tetrafluoroborate (BF4 –), hexafluorophosphate (PF6 –), perchlorate (ClO4 –), and bis(trifluoromethanesulfonyl)imide (TFSI–), and a comparison of their stability in solution and in the solid state. In the solution, UV–vis spectroscopy and rotating ring-disk electrode voltammetry show similar stability trends with respect to anion identity, with the TFSI– salt being the most stable. In the solid state, these compounds show remarkable stability in air and at elevated temperatures, with the ClO4 – salt surviving after being heated at 90 °C overnight in air. The different trends in MEEPT-X stability with X highlight the importance of concentration and the environment on the overall stability.
Transition metal dissolution from high-voltage Li-ion battery cathodes disrupts the formation and performance of the solid-electrolyte interphase (SEI). SEI contamination by transition metals results ...in continual Li loss and severe capacity fade. Fundamental understanding of how metals undermine SEI passivation is necessary to mitigate this degradation. This two-part study interrogates the mechanisms by which transition metals facilitate through-film charge-transfer and SEI failure. Part I presents experimental results in which we intentionally contaminate SEIs with Mn, Ni, and Co. Rotating disk electrode voltammetry of a redox mediator quantifies how each metal impacts the charge-transfer characteristics of the SEI. A physics-based model finds that all three metals disrupt the electronic properties of the SEI more than the morphology. Surprisingly, the Butler-Volmer kinetics of charge-transfer through a Mn-contaminated SEI are an order of magnitude faster than for a Co-contaminated SEI, even with similar embedded metal concentrations. Such trends between metals are inconsistent with bandgap predictions from density functional theory, implying an alternative redox-cycling mechanism, which is mathematically developed and compared to experiment in Part II.
We describe a novel coarse-grained simulation method for modelling the dynamics of globular macromolecules, such as proteins. The macromolecule is treated as a continuum that is subject to thermal ...fluctuations. The model includes a non-linear treatment of elasticity and viscosity with thermal noise that is solved using finite element analysis. We have validated the method by demonstrating that the model provides average kinetic and potential energies that are in agreement with the classical equipartition theorem and that the nodal velocities have the correct Gaussian distribution. In addition, we have performed Fourier analysis on the simulation trajectories obtained for a series of linear beams to confirm that the correct average energies are present in the first two Fourier bending modes and that the probability distribution of the amplitudes of the first two Fourier modes match the theoretical results. We demonstrate spatial convergence of the model by showing that the anisotropy of the inertia tensor for a cubic mesh converges as a function of the mesh resolution. We have then used the new modelling method to simulate the thermal fluctuations of a representative protein over 500ns timescales. Using reasonable parameters for the material properties, we have demonstrated that the overall deformation of the biomolecule is consistent with the results obtained for proteins in general from atomistic molecular dynamics simulations.
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![The development of [(124)I]...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0008-5472/small "The development of [(124)I]iodinated-VG76e: a novel tracer for imaging vascular endothelial growth factor in vivo using positron emission tomography")
