Maximum Life Research Articles

Longevity Estimates of Canary Palms and Dragon Trees via Radiocarbon Dating: Initial Results.

Correctly estimating the maximum lifespan of plant species is a necessary component of demographic and life-history studies, which, in turn, are needed for understanding climatic impacts. Arboreal monocotyledons, which can grow to >30 m in height and >5 m in trunk perimeter, are difficult to age because they do not undergo seasonal dormancy; hence, their longevity has been estimated using various size-related methods. In this study, we tested radiocarbon (14C) dating with Accelerator Mass Spectrometry (AMS) as an additional tool for determining the age of two iconic monocotyledons: the Canary Island palm and the dragon tree. A total of 25 samples were collected from the basal stem of four palms and five dragon trees on Gran Canaria and Tenerife and then processed using the most advanced 14C-AMS analysis available. Calibration curves provided by the "IntCal group" were used to determine the oldest possible age of each sample, and 16 of them were found to be "modern", i.e., formed after the 1950s. Nine samples that were either collected from exterior, but lignified, palm tissues or from interior, and lignified, dragon tree tissues suggested ages > 300 years. Given the constant improvement of 14C-AMS tools, they can contribute to the further refinement of existing scientific knowledge on Macaronesian charismatic megaflora.

KYNURENINE PATHWAY INHIBITORS COMBINED WITH NAD+ PRECURSORS INCREASES LONGEVITY GENE EXPRESSION IN DROSOPHILA

Abstract With rates of aging-related functional decline rising, the need for novel intervention strategies to extend lifespan has increased. In humans, the kynurenine pathway (KP) metabolizes tryptophan and produces nicotinamide adenine dinucleotide (NAD+). KP is correlated negatively with longevity and increased KP metabolite concentrations decrease the average and maximum lifespans in flies. However, genetic and pharmacological inhibition of tryptophan metabolism and dietary supplementation of NAD+ precursors increase the average and maximum lifespans in flies. To comprehensively explore the effects of KP manipulation, we fed DGRP_229 Drosophila males diets infused with ⍺-MT (KP inhibitor), nicotinamide (NAM, an NAD+ precursor), or the combination of NAM and ⍺-MT. We found that all treatments resulted in increased average and maximum lifespans, with the combination treatment displaying the greatest increase compared to the control of 30% (P< 0.0001). The combination treatment resulted in an average lifespan increase of 15% in relation to ⍺-MT alone (P< 0.0001) and 18% in comparison to NAM alone (P< 0.0001). To gain more insight into the biological mechanisms through which different treatments affect lifespan, we performed qRT-PCR on 11 longevity genes in Drosophila. We found that the combination treatment significantly increased the expression of gigas (Gig) (P=0.03), which interacts with Tsc1 to control cellular growth by regulating insulin and TOR signaling pathways, and sirtuin 1 (Sirt1) (P=0.03), an NAD+-dependent histone deacetylase. Our results demonstrate that the combined treatment of KP inhibition and NAD+ precursor elicits a transcription response similar to other lifespan-enhancing treatments and could be used as an alternative intervention method.

COMPARATIVE TRANSCRIPTOMICS AND PROTEOMICS ACROSS SPECIES

Abstract Mammals differ more than 100-fold in maximum lifespan. Here, we conducted comparative transcriptomics on 26 species with diverse lifespans. We identified thousands of genes with expression levels negatively or positively correlated with a species’ maximum lifespan (Neg- or Pos-MLS genes). Neg-MLS genes are pri- marily involved in energy metabolism and inflammation. Pos-MLS genes show enrichment in DNA repair, microtubule organization, and RNA transport. Expression of Neg- and Pos-MLS genes is modulated by interventions, including mTOR and PI3K inhibition. Regulatory networks analysis showed that Neg-MLS genes are under circadian regulation possibly to avoid persistent high expression, whereas Pos-MLS genes are tar- gets of master pluripotency regulators OCT4 and NANOG and are upregulated during somatic cell reprogramming. Pos-MLS genes are highly expressed during embryogenesis but significantly downregulated after birth. This work provides targets for anti-aging interventions by defining pathways correlating with longevity across mammals and uncovering circadian and pluripotency networks as central regulators of longevity. I will also discuss integrating this transcriptome and proteome data.

3-HK SUPPLEMENTATION INCREASES NICOTINATE PHOSPHORIBOSYLTRANSFERASE (NAPRT) EXPRESSION IN DROSOPHILA

Abstract The increasing prevalence of physical frailty and aging related diseases in older adults necessitates the development of novel biological strategies to slow age-related declines. In humans, tryptophan metabolism through the kynurenine pathway (KP), which produces the energy metabolite and cellular cofactor nicotinamide adenine dinucleotide (NAD+), has been linked to various aging-related diseases including metabolic syndrome, neurodegenerative diseases, and physical frailty. Elevated levels of KP metabolites, such as 3-hydroxykinurenine (3-HK), correlate negatively with lifespan and physical function. A profile of downstream KP metabolites in the serum of older adults showed that 3-HK was increased in frail compared to both non-frail and young subjects, and liver kynurenine/tryptophan ratio correlates negatively with maximum lifespan in twenty-six mammalian species. To comprehensively explore the effects of elevated cytotoxic KP metabolites, we fed DGRP_229 Drosophila males diet infused with 3-HK. We found that treatment with 3-HK reduced average lifespan by 17% (P< 0.0001) compared against control. To elucidate the biological mechanisms of 3-HK treatment, we performed qRT-PCR on 11 genes involved in tryptophan metabolism. We found that treatment with 3-HK significantly decreased the expression of nicotinate phosphoribosyltransferase (Naprt) (P=0.0022), which plays an important role in NAD+ biosynthesis and protects against oxidative stress. Our findings indicate that some of the detrimental effects observed after 3-HK supplementation may be mediated by changes in NAD+ biosynthesis and highlight the potential feasibility of using NAD+ supplementation as an intervention method.

DIETARY RESTRICTION OF ISOLEUCINE INCREASES THE HEALTHSPAN AND LIFESPAN OF GENETICALLY HETEROGENEOUS MICE

Abstract Low protein (LP) diets promote health and longevity in diverse species, andreducing dietary levels of the branched-chain amino acids (BCAAs) leucine, isoleucine and valine recapitulates these effects in C57BL/6J mice, promoting metabolic health in both sexes, and increases lifespan while reducing frailty in males. Each BCAA has unique metabolic effects, and we recently showed that restriction of isoleucine is both sufficient to promote metabolic health and required for the metabolic benefits of an LP diet in C57BL/6J males. Here, we tested the hypothesis that specifically restricting dietary isoleucine could promote healthy aging in adult genetically heterogenous UM-HET3 mice. We find that isoleucine restriction (IleR) improves the metabolic health of both young and old HET3 mice, promoting leanness and glycemic control in both sexes, and reprograms hepatic metabolism, blunting age-related molecular changes in males and, to a lesser extent, in females. Finally, we find that IleR reduces frailty and extends both the median and maximum lifespan of both male and female HET3 mice, but to a much greater degree in males. Our results demonstrate that restricting dietary isoleucine can increase health span and longevity in a genetically diverse population of mice and suggest that reducing dietary levels of isoleucine, or drug regimens that mimic this effect, may be a novel intervention to promote healthy aging.

METABOLOMICS OF LONGEVITY AND LIFESPAN

Abstract Serum metabolomics has been an important source of biomarkers of aging and longevity for years. This symposium will bring together investigators from large studies of human longevity to provide an overview of recent discoveries on serum metabolomics of aging and extreme human longevity, their connections to genetic variations, and highlight the challenges of correlating metabolomic profiles of aging in human studies and across multiple species. Dr. Sebastiani will describe results from analyses of serum metabolomics of participants enrolled in the Long Life Family Study, highlight similarities and differences between metabolomic profiles of old age and extreme old age, and some connections with genetics of extreme human longevity. Dr. Rappaport will connect specific variations of the APOE alleles to metabolomic profiles and describe a possible role of bioenergetics pathways in mediating the effect of APOE to longevity and resistance to Alzheimer’s disease. Dr. Monti will expand the characterization of metabolomics of aging and extreme human longevity in a large metabolomic study of very old centenarians by using traditional statistical analyses and novel machine learning techniques. His analysis identifies rich signatures of aging and longevity that include well known metabolites and point to bile acids and several classes of steroids as important marker of longevity. Analytical innovations will be taken further by Dr. Schork who will introduce a novel approach based on distance of profiles to analyze multiple metabolites simultaneously and show the value of this approach to analyze metabolomic profiles of maximum lifespan across multiple species. This is a Geroscience Interest Group Sponsored Symposium.

Proactive strengthening of U-rib butt-welded joints in steel bridge decks using adhesively bonded Fe-SMA strips

U-rib butt-welded joints are one of typical fatigue-prone details in early aging orthotropic steel bridge decks, which poses a potential threat to the structural behavior and safe operation of steel bridges. Therefore, it is of great importance to seek out an effective way for retrofitting fatigue cracks. This study proposes an efficient prestressing technique using bonded iron-based shape memory alloy (Fe-SMA) to strengthen cracked U-rib butt-welded joints proactively. A series of static and fatigue tests were conducted on the cracked specimens to investigate the feasibility and fatigue improvement of the proposed technique. Results from the experiments demonstrated that applying prestressing force by heating Fe-SMA strips is a convenient and reliable technique. Activated Fe-SMA strips could introduce significant compressive stresses and provide additional stiffness for the cracked components. This led to a reduction of the mean stress and fatigue stress ranges at the U-rib butt-welded joints under cyclic loading. All the cracked specimens strengthened with adhesively bonded Fe-SMA strips presented excellent fatigue performances, with a maximum equivalent fatigue life extension of 4.09 times compared to the specimen before cracking. Numerical simulation was also performed to better understand the test results. It was demonstrated that prestressed Fe-SMA strengthening could decrease the mode-I stress intensity factor (SIF) at the crack tip, indicating the beneficial effects of the prestressing in retarding crack and its further propagation. In conclusion, the use of adhesively bonded Fe-SMA strips for strengthening cracked butt welds is highly effective in improving the fatigue performance, even better than bonding CFRP.

The Effect of Precipitates on the Stress Rupture Properties of Laser Powder Bed Fusion Inconel 718 Alloy

Improving the high-temperature stress rupture properties of Inconel 718 (IN718) alloys is crucial for enhancing aircraft engine performance. By using the laser powder bed fusion (LPBF) technique, IN718 alloys were crafted at varying volumetric energy densities (VED) in this study. The dendrite growth mode, reinforcing phase distribution and high temperature stress rupture properties of various VED samples were investigated. The results showed that the stress rupture life and the uniform elongation of the samples both first increased and then decreased with the increase in VED. When the VED was 60 J/mm3, the maximum rupture life and elongation of the sample were 43 h and 3.8%, respectively. As the VED increased, the angle of dislocation in the dendrite decreased while the spacing between primary dendrite arms increased, resulting in an increase in the size and volume fraction of the Laves phase. Following a heat treatment, the δ phase would nucleate preferentially around the dissolved Laves phase causing an increase in the volume fraction of the δ phase with the increase in VED. The creep voids readily formed around the δ phase are distributed along the grain boundaries, while the inhomogeneous δ phase and fine grains facilitated crack initiation and propagation. Furthermore, a significant quantity of the δ phase consumed the Nb element, thereby hindering adequate precipitation in the γ″ phase and causing cracks.

Optimizing UVC-LED application to improve the shelf life of vacuum-packed refrigerated stored Nile tilapia (Oreochromis niloticus) fillets.

Although ultraviolet-C light-emitting diode (UVC-LED) has proven antimicrobial effectiveness doses needed to reach it cause adverse effects on the physicochemical quality of fish, and thus, optimization studies are crucial to boost its industrial application. This study aimed to identify optimal UVC-LED conditions for maximum shelf life extension with the least possible quality changes of refrigerated stored tilapia fillets from a central composite rotatable design (CCRD). UVC-LED powers (1, 1.38, and 1.58mW/cm2 ) and times (500, 1800, and 2700s) were set on the CCRD, which generated 11 treatments, including three replicate experiments. Treatments were analyzed for total aerobic psychrotrophic count, lipid oxidation, instrumental color, and texture parameters on days 0, 2, 4, 7, 11, and 14. The UVC-LED affected shelf life and physicochemical parameters in a nonlinear fashion. UVC-LED-treated fish had increased shelf life by 2.80-4.76 days and increase or decrease in lipid oxidation (0.025-0.276mg of malondialdehyde [MDA]/kg), total color change (∆E=3.47-9.06), and hardness (1.31-8.51N) over the refrigerated storage depending on specific UVC-LED conditions applied. The optimal UVC-LED condition was 0.97mW/cm2 with 2503.6s (2428.50mJ/cm2 ), which increased the fillet's shelf life by 2.5-fold (2 days) while maintaining quality closer to the original throughout refrigerated storage, resulting in ∆E<5, an increase of only 0.05mg of MDA/kg, and preservation of the decrease in hardness by 3.38N compared to its control counterparts. Therefore, it represents an eco-friendly technology that can easily scaled industrially to enhance the sustainable fish production chain. PRACTICAL APPLICATION: The high fish perishability is a global concern due to food safety risks and waste generation impacting the environment adversely, especially nowadays, where fish production and consumption have increased, and there are more evident efforts to sustainable production. UVC-LED is an eco-friendly technology with proven antimicrobial effectiveness but doses needed to reach this effect enhance oxidative degradation. Despite that, optimization studies concerning the maximum shelf life extension while retaining the physicochemical quality of refrigerated stored fish are a gap in the literature and a barrier to its industrial application. Our findings are helpful in sustainably enhancing the fish production chain.

DNA methylation rates scale with maximum lifespan across mammals

DNA methylation rates have previously been found to broadly correlate with maximum lifespan in mammals, yet no precise relationship has been observed. We developed a statistically robust framework to compare methylation rates at conserved age-related sites across mammals. We found that methylation rates negatively scale with maximum lifespan in both blood and skin. The emergence of explicit scaling suggests that methylation rates are, or are linked to, an evolutionary constraint on maximum lifespan acting across diverse mammalian lineages.

The rate of epigenetic drift scales with maximum lifespan across mammals

Epigenetic drift or “disorder” increases across the mouse lifespan and is suggested to underlie epigenetic clock signals. While the role of epigenetic drift in determining maximum lifespan across species has been debated, robust tests of this hypothesis are lacking. Here, we test if epigenetic disorder at various levels of genomic resolution explains maximum lifespan across four mammal species. We show that epigenetic disorder increases with age in all species and at all levels of genomic resolution tested. The rate of disorder accumulation occurs faster in shorter lived species and corresponds to species adjusted maximum lifespan. While the density of cytosine-phosphate-guanine dinucleotides (“CpGs”) is negatively associated with the rate of age-associated disorder accumulation, it does not fully explain differences across species. Our findings support the hypothesis that the rate of epigenetic drift explains maximum lifespan and provide partial support for the hypothesis that CpG density buffers against epigenetic drift.

Mechanical characteristics determination of aircraft wing carbon plastic panel

The paper presents the method of calculating the mechanical characteristics of multilayer composite panels. The optimal sequence of laying out monolayers was selected. The mechanical behavior of the composition is determined by the ratio of the properties of the reinforcing elements and the matrix, as well as the strength of the connection between them. Among the most important requirements for the designs of modern aircraft, we can mention the minimum weight, the maximum stiffness and strength of the nodes, the maximum service life of the structures in operational conditions, and high reliability. With the help of the developed methodology, the elastic properties of the composite material with different angles of laying layers were determined. Calculations of the mechanical characteristics of carbon-plastic panels made of carbon tape and carbon fabric are given.

Association of Euterpe oleracea, Bixa orellana, Myciaria dubia, and Astrocaryum aculeatum (the Terasen® Nutraceutical) Increases the Lifespan of Caenorhabditis elegans

Aging is a complex process associated with tissue degeneration and an increased risk of age-related diseases. This study aimed to evaluate the impact of Terasen®, a nutraceutical containing standardized extracts of Euterpe oleracea, Myrciaria dubia, and purified oil of Bixa orellana and Astrocaryum aculeatum on the lifespan of Caenorhabditis elegans. The findings demonstrated that Terasen® exhibited significant radical scavenging in vitro, decreased the feeding behavior of C. elegans without affecting the animals’ final size, increased the eggs laid in a concentration-dependent fashion, although the total progeny was reduced compared to the control, and increased the median and maximum lifespan. These findings suggest that Terasen® may improve the lifespan in C. elegans, warranting further investigation.

Comparative biology and non-traditional approaches for basic aging research for facilitating translational studies.

As humans, we aspire to healthy aging and ideally reaching our maximal lifespan. That, however, requires optimizing resilience to stressors and minimizing exposure to factors that accelerate aging. Understanding the complexities of aging processes involves characterizing the causal bases of physical, physiological, and cognitive deficits that accumulate over time, eventually culminating in reduced functionality and decreased resistance to disease and environmental stressors. Both the progression of age-related conditions and onset of diseases are affected by environmental stressors; however, the basis for increased susceptibility remains poorly understood. Furthermore, the actions of some environmental stressors, such as endocrine disruptors, can alter both developmental and aging processes, contributing to lifelong issues with inflammatory and neurodegenerative conditions. This manuscript focuses on the comparative biology and evolution of aging and longevity. The status of an array of animal models and potential for specific geroscience translational applications is addressed by asking these questions. What animal models are currently available for aging and translational geroscience? What are the key roadblocks and barriers for studies of healthy aging, and how might specific animal models be useful? Are research tools available? Which vertebrate animal models can specifically address targeted questions in human aging processes? Can information be synthesized for a range of vertebrate species to identify suitable animal models for addressing specific research questions in geroscience, especially relative to basic physiological function, timing and trajectory of disease progression, effects of environmental stressors, and potential for regenerative medicine?

Effect of double cracks merge on fatigue crack propagation life of engine heat shield

To prevent overheating of the airframe, an aero-engine is often designed to play a role in shielding heat radiation heat shield. Since the thermal protection system used in this paper is active, it is subject to a cold gas pressure load on the outside and a thermal radiation load from the combustion chamber on the inside. Therefore, the working environment of the heat shield is very harsh. Taking the heat shield of an aero-engine as the research object, the finite element method (FEM) is used to analyze the thermal-mechanical coupling (TMC) of the actual working process of the heat shield, and the mechanical quantities such as the thermal stresses and mechanical stresses are comprehensively analyzed. According to the finite element simulation results, two stress concentrations are obtained near the connecting lug, and the stress concentrations are set as the initial crack insertion locations. Using the theory related to linear elastic fracture mechanics (LEFM) and the Forman-Newman-de Koning (FNK) model, the fatigue crack propagation life (FCPL) and its law of the merged double cracks of the engine heat shield are calculated. The results show that the FCPL of the heat shield decreases nonlinearly and the critical crack length decreases linearly under different working conditions. This law applies not only to single cracks but also to merged double cracks. In terms of FCPL, the merged double cracks are lower than the single crack with a maximum life reduction rate of 70.9%.

Fatigue performance of hydraulic asphalt concrete under uniaxial constant-amplitude tensile cycle loading

The fatigue properties of hydraulic asphalt concrete (HAC) have significant impact on the impervious performance and safety of HAC embankment dam. Therefore, this study investigated the fatigue performance of HAC, including fatigue deformation, tensile failure mode and fatigue life, and proposed a model for predicting HAC fatigue life considering stress level, cycle frequency, and failure probability. For these purposes, a constant-amplitude continuous cyclic tensile test was conducted on dumbbell-shaped HAC samples at different stress levels and cyclic frequencies. The results indicated that the failure strains of HAC at different fatigue tensile loading conditions was as high as 4.6 %, which is about 2 times the monotonic tensile strain. The failure surface of the HAC sample has a larger proportion of aggregate fracture with increasing stress level and cycle frequency. In addition, the fatigue life increases significantly with the cycle frequency. Specially, at the stress level of 0.5, the maximum fatigue life can reach up to 4365 cycles with a frequency of 5 Hz, about 10 times greater than that with a frequency of 0.5 Hz. Finally, the predection model proposed based on the double logarithmic fatigue equation can accurately predict the fatigue life of HAC.

Friction Stir Welding Tool Life Assessment Through Fatigue Analysis

Abstract Friction stir welding is a solid-state joining process used to weld various materials. Tool life is an important consideration when welding strong metals with the Friction stir welding technique (FSW). The current research aims to calculate tool life by mathematical derivation and simulation using ANSYS transient structural analysis. There are two tool materials and five-pin profiles to consider. The calculated tool life using mathematical formulation is within 15% of the simulation outcome. Further changes are made to the simulation to make the tool life estimate more realistic under FSW’s operation. PcBN tool has superior mechanical properties over the tungsten carbide tool, so the procedure started with the tungsten carbide tool. The conical pin profile is giving 31466 cycles of tool life, which is 70 min run time while working at 450 rpm rotational speed. As a result, for high-strength materials joining, the tool must be chosen based on tool life parameters. The addition of a 1.5 mm fillet at the pin-to-shoulder junction has improved the tool life by 1147 cycles. The PcBN tool is simulated with a conical tool with new pin profiles of conical with grooves and cylindrical fillet with grooves. The maximum tool life of 94018 cycles is obtained for the conical PcBN tool.

Исследование нейропротекторных свойств экстракта черноплодной рябины (×Sorbaronia mitschurinii) у линии Drosophila melanogaster, моделирующей болезнь Альцгеймера

Aging is accompanied by a widespread deterioration in the state of the body (physiological and psychological) with the concomitant manifestation of neurodegenerative diseases (dementia, Alzheimer’s disease, Parkinson’s disease). Biologically active substances contained in the fruits of chokeberry have previously shown a neuroprotective potential in relation to model organisms in vivo, so we put forward a hypothesis about the possible neurodenegeroprotective potential of the ethanol extract of chokeberry (×Sorbaronia mitschurinii) on Drosophila melanogaster with overexpression of the precursor of human beta-amyloid UAS-Aβ42. Its accumulation in human brain cells triggers the development of Alzheimer’s disease. In this work, we have studied the effect of chokeberry extract at a concentration of 10 mg/ml on the lifespan of Drosophila model of Alzheimer’s disease. The extract increases the median and maximum lifespan of females by 11 %, as well as the median lifespan of males by 2 % but reduces their maximum lifespan by 3 %. These results indicate the neuroprotective effect of chokeberry extract.

Ultrahigh‐Rate Na/Cl2 Batteries Through Improved Electron and Ion Transport by Heteroatom‐Doped Bicontinuous‐Structured Carbon

AbstractRechargeable sodium/chlorine (Na/Cl2) batteries are emerging candidates for sustainable energy storage owing to their superior energy densities and the high abundance of Na and Cl elements. However, their practical applications have been plagued by the poor rate performance (e.g., a maximum discharge current density of 150 mA g−1), as the widely used carbon nanosphere cathodes show both sluggish electron‐ion transport and reaction kinetics. Here, by mimicking the sufficient mass and energy transport in a sponge, we report a bicontinuous‐structured carbon cubosome with heteroatomic doping, which allows efficient Na+ and electron transport and promotes Cl2 adsorption and conversion, thus unlocking ultrahigh‐rate Na/Cl2 batteries, e.g., a maximum discharge current density of 16,000 mA g−1 that is more than two orders of magnitude higher than previous reports. The optimized solid–liquid–gas (carbon–electrolyte–Cl2) triple interfaces further contribute to a maximum reversible capacity and cycle life of 2,000 mAh g−1 and 250 cycles, respectively. This study establishes a universal approach for improving the sluggish kinetics of conversion‐type battery reactions, and provides a new paradigm to resolve the long‐standing dilemma between high energy and power densities in energy storage devices.

Ultrahigh-Rate Na/Cl2 Batteries Through Improved Electron and Ion Transport by Heteroatom-Doped Bicontinuous-Structured Carbon.

Rechargeable sodium/chlorine (Na/Cl2 ) batteries are emerging candidates for sustainable energy storage owing to their superior energy densities and the high abundance of Na and Cl elements. However, their practical applications have been plagued by the poor rate performance (e.g., a maximum discharge current density of 150 mA g-1 ), as the widely used carbon nanosphere cathodes show both sluggish electron-ion transport and reaction kinetics. Here, by mimicking the sufficient mass and energy transport in a sponge, we report a bicontinuous-structured carbon cubosome with heteroatomic doping, which allows efficient Na+ and electron transport and promotes Cl2 adsorption and conversion, thus unlocking ultrahigh-rate Na/Cl2 batteries, e.g., a maximum discharge current density of 16,000 mA g-1 that is more than two orders of magnitude higher than previous reports. The optimized solid-liquid-gas (carbon-electrolyte-Cl2 ) triple interfaces further contribute to a maximum reversible capacity and cycle life of 2,000 mAh g-1 and 250 cycles, respectively. This study establishes a universal approach for improving the sluggish kinetics of conversion-type battery reactions, and provides a new paradigm to resolve the long-standing dilemma between high energy and power densities in energy storage devices.