bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prognostic value of cardiopulmonary exercise test in children with congenital heart defects
Authors: Terol Covadonga , Hagen Juliette , Rammeloo Lukas , Kuipers Irene M , Blom Nicolaas A , ten Harkel Arend DJ 
Published: August 2024

BackgroundCardiopulmonary exercise testing (CPET) has an important prognostic value in adults with different congenital heart defects (CHDs) and is a useful tool for risk stratification and clinical decision-making. In this retrospective study, we studied the prognostic value of CPET in paediatric patients with CHD.Methods411 CPET performed by paediatric patients with different CHDs were evaluated in this retrospective study. Medical records were reviewed to determine the presence of cardiac events. Participants were classified using the 2018 AHA/ACC guideline for the management of adults with CHD that combines anatomical complexity and current physiological stage.Results411 patients with a median age at test of 12 years, 51 patients with simple CHD, 170 patients with moderate complexity CHD and 190 with high complexity CHD underwent CPET. Overall, CPET parameters were lower than the reference values (%predicted VO2peak=75% and %predicted oxygen uptake efficiency slope (OUES)=79%), showing worst exercise capacity in the most complex types of CHD (Group III: %predicted VO2peak=72% and %predicted OUES=75%). Seventy-one patients presented with cardiac events at a median time from CPET to first event of 28 months. Patients with cardiac events had lower exercise performance as compared with patients without cardiac events as determined by the submaximal variables (%predicted OUES: HR=2.6 (1.5–4.4), p<0.001 and VE/VCO2: HR=2.2 (1.4–3.5), p=0.001).ConclusionReduced exercise capacity at young age is related to a higher probability of future cardiovascular events in paediatric patients with CHD. Submaximal exercise variables can be used instead when maximal exercise cannot be achieved.
Synergistic Electrocatalyst-Cathode Architecture for Stable Long-Term Cycling Lithium-Sulfur Batteries
Authors: Nazir Aqsa , Pathak Anil , Hamal Dambar , Motevalian Saeme , Awadallah Osama , Drozd Vadym , El-Zahab Bilal 
Published: August 2024

Lithium-sulfur (Li-S) batteries are a promising candidate for next-generation energy storage owing to the high theoretical capacity of sulfur (1,675 mAh g−1). However, the intrinsically low electrical conductivity of sulfur and complex multistep electrolyte-mediated redox reactions involving soluble lithium polysulfide intermediates engender critical challenges toward practical realization. Specifically, migration and diffusion of higher-order lithium polysulfides provokes continuous loss of active sulfur species, yielding premature capacity fade. Electrochemical kinetics also remain sluggish due to the insulating nature of sulfur cathodes, which require engineering designs to accelerate charge transfer.
Rational morphological and compositional cathode tuning represents a compelling strategy for addressing fundamental Li-S limitations. Herein, we develop an extended cathode architecture composed of a porous carbon nanotube network decorated with homogenously dispersed nanocatalysts. Electron microscopy and spectroscopy analysis verify platinum group metals are well-incorporated both within internal channels and external surface sites of conductive carbon nanotubes. The composite framework affords multifaceted functionality arising from synergistic chemical and structural attributes of components. Nanocatalyst sites demonstrate a pronounced chemical affinity toward soluble polysulfide intermediates, effectively localizing them within cathode, minimizing diffusional losses toward the anode. This anchoring phenomenon is complemented by the inherent microporosity of the high-surface-area nanotube network, further obstructing polysulfide migration through a confinement effects. Concurrently, noble metal nanoparticles facilitate the redox conversion of trapped higher-order polysulfides into solid Li2S alleviating the precipitation of electrically insulating discharge products. The excellent electrical conductivity of CNTs ensures efficient charge transport to all incorporated sulfur active materials, further maximizing reversible utilization.
As a result of complementary polysulfide confinement and electrocatalytic conversion functionalities, Li-S coin cells exhibit enhanced reversible capacities exceeding 900 mAh g−1 for over 500 cycles at 0.558 A g−1. Notably, over 500 cycles, minimal capacity decay of 0.018% per cycle and 92% retention of the initial capacity are obtained at moderate sulfur loadings highlighting the exceptional cycling stability enabled by engineered cathodes. Outstanding rate performance is also demonstrated with the delivery of 854 mAh g−1 capacity at a very high current density of 1.675 A g−1. Our rationally designed cathode architecture provides critical mechanistic insight toward addressing fundamental bottlenecks to progress Li-S technologies.
ALD with Enhanced Nucleation on Polymeric Separator for Improved Li-S Batteries
Authors: D'Acunto Giulio , Shuchi Sanzeeda Baig , Zheng Xueli , Cui Yi , Bent Stacey F. 
Published: August 2024

Lithium-sulfur (Li-S) batteries, known for their exceptional energy densities, are at the forefront of the next generation of energy storage systems. However, their practical application is hindered by the polysulfide shuttle effect, which significantly impairs discharge capacity and cycling stability. This research introduces a novel solution to these challenges through the use of atomic layer deposition (ALD) of Al₂O₃ on commercial polypropylene/polyethylene/polypropylene (PP/PE/PP) separators.
ALD is a thin-film deposition technique that allows for precise control of layer thickness and composition at the atomic scale. ALD is characterized by its ability to produce extremely uniform and conformal layers, making it an ideal method for applications where surface chemistry plays a critical role, such as in battery separators. The technique is particularly advantageous in applications requiring high precision and control, like in our approach to enhancing Li-S batteries.
In our study, the inert separator was treated with UV ozone to enhance the nucleation of ALD precursors, with the goal of reducing polysulfide shuttling. The use of ALD-modified separators in batteries demonstrated a marked increase in specific capacity, reaching approximately 1150 mAh/g, and reduced overpotential, indicative of improved kinetic efficiency. Further, we explored the structural and chemical modifications of the separator, employing X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Our findings indicate that ALD of Al₂O₃ on the separators significantly improved the adsorption of polysulfides, thereby mitigating the shuttle effect.
In addition to improved polysulfide interaction, we also examined the impact on polysulfide adsorption on the formation of the solid-electrolyte interphase (SEI). Our results showed that modified batteries exhibited no polysulfide presence on the anode, suggesting a stable and effective SEI. This observation is significant, as it indicates that our approach enhances specific capacity and cycling stability by controlling the formation of a more effective SEI.
Overall, our research demonstrates how strategic modifications at the separator level, particularly through the application of ALD and UV ozone, can significantly enhance the overall performance of Li-S batteries. By leveraging the unique advantages of ALD, especially through Al₂O₃ deposition, we provide a viable pathway to enhance the efficiency and stability of Li-S batteries.
Sodium Halide-Based Solid Electrolyte with High Ionic Conductivity
Authors: Tan Yuan , Su Laisuo 
Published: August 2024

Sodium-ion batteries (SIBs) are considered one of the most prominent alternatives to lithium-ion batteries (LIBs) because of the abundance of sodium resources on Earth. However, compared to Li, Na has a heavier atomic weight (23 g mol–1 vs. 6.9 g mol–1) and higher standard potential, leading to lower volumetric and gravimetric energy density of SIBs than LIBs. The energy density of state-of-the-art room-temperature SIBs is in the range of 75 – 165 W h kg–1 or 250 – 375 W h L–1. To increase the energy density of SIBs, Na metal is proposed to be used as the anode material due to its superior theoretical specific capacity (1166 mA h g–1). To tackle the safety challenges brought by using Na metal, applying solid electrolytes (SEs) has been proposed to be an effective strategy. Despite the tremendous progress that has been made in the past decades, the progress and application are still in the infancy, experiencing numerous challenges for sodium solid-state batteries due to inherently low room-temperature ionic conductivity, interface complications, and fabrication.
Inorganic halide-based SEs have emerged as a game changer because of their fast-conducting characteristics, adequate thermodynamic stability, great deformability, and good oxidative stability.1 Moreover, halide-based SEs are generally stable against moisture owing to their positive hydrolysis reaction energy. However, most of the studied halide-based SEs are based on the Li-ion system, with only a few based on the Na-ion system. Moreover, despite halide-based Na SEs theoretically having high ionic conductivity,2 experimental obtained samples have much lower ionic conductivities compared to their Li counterparts (usually < 0.1 mS cm–1). Therefore, developing halide-based SEs with high Na+ ionic conductivity is crucial for Na ASSBs. We recently identified a new Na halide-based SE with a room temperature Na+ ionic conductivity over 1 mS cm–1. The activation energy is also as low as 0.23 eV. Interestingly, the material shows a mixed amorphous and crystalline phase, and its ionic conductivity decreases with the increase of the crystalline phase. The ionic conductivity of > 1 mS cm–1 is already comparable to some organic liquid electrolytes and thus is sufficient for many practical applications. The developed strategy has the potential to be applied to other halide-based SEs to improve their ionic conductivity, promoting the development of SIBs.
(1) Huang, J.; Wu, K.; Xu, G.; Wu, M.; Dou, S.; Wu, C. Recent Progress and Strategic Perspectives of Inorganic Solid Electrolytes: Fundamentals, Modifications, and Applications in Sodium Metal Batteries. Chem. Soc. Rev.
2023, 52 (15), 4933–4995.
(2) Qie, Y.; Wang, S.; Fu, S.; Xie, H.; Sun, Q.; Jena, P. Yttrium–Sodium Halides as Promising Solid-State Electrolytes with High Ionic Conductivity and Stability for Na-Ion Batteries. J. Phys. Chem. Lett.
2020, 11 (9), 3376–3383.
Text Mining Analysis of Beyond Lithium-Ion Batteries
Authors: Kilic Aysegul , Oral Burcu , Eroglu Damla , Yildirim Ramazan 
Published: August 2024

Li-ion batteries (LIBs) are the most commonly used energy storage technology in various consumer goods, including electric vehicles. However, several alternatives, so-called beyond-LIBs, are greatly investigated to decrease battery costs using abundant and globally distributed materials with high theoretical capacities. Among the diverse beyond LIB systems, this paper includes the top 6 researched chemistries: univalent (Na- and K-) and multivalent (Zn-) metal-ion, metal-air (Li-air and Zn-air), and Li-S batteries. Naturally, all these six battery chemistries have problems that must be addressed before mass commercialization. Although there are 24,523 publications on these batteries, a parallel examination of these technologies to transfer knowledge must be included in the literature. This study used text mining analysis to study the most common keywords and word connections for beyond-LIBs to learn from the general trends in the literature [1].
First, the dataset was built using the Web of Science database in June 2023 by applying all the possible alternative names of beyond LIBs in the search with the Title option. Hence, the abstracts, author keywords, and keywords plus for each battery chemistry were obtained together with the article information. Afterward, data cleaning and text mining analysis were performed using the R Studio environment, specifically stringr, tm, pluralize, and tidytext libraries. The research interests in the primary battery parts and the single material-related words and two-word bigrams were investigated.
The bibliometric analysis has shown that Li-S and Na-ion batteries are the most popular research areas in the beyond LIB literature. On the other hand, interestingly, Li-air batteries lost their popularity to Zn-air in around 2015. Publications on Zn-ion batteries have a sharp increasing trend, and K-ion batteries have started to share this research interest. When the single-word results are analyzed, it has been seen that anode, cathode, and electrolyte are the most commonly studied battery sections for Na- and K-ion, Zn-ion and Li-S, and finally, Zn- and Li-air batteries, respectively. Apart from the battery parts, regardless of the chemistry, the high frequency of carbon and graphene keywords are detected; hence, bigram analysis is further performed on these keywords to see the most associated words with these materials. It has been seen that carbon nanotubes are the first and nanofibers are the second preferred form of carbons, whereas the graphene oxides are found to be promising for all beyond LIBs, given only good results are reported in the literature.

References

[1] A. Kilic, B. Oral, D. Eroglu, R. Yildirim, Machine learning for beyond Li-ion batteries: Powering the research, Journal of Energy Storage. 73 (2023) 109057. https://doi.org/10.1016/j.est.2023.109057.

Figure 1
(Invited) Functional Fluorous Nanocarbons
Authors: Boltalina Olga V. 
Published: August 2024

Fluorination was one of the first hypothesized chemical reactions for a buckyball that could yield C60F60 with "superlubricant" properties. [1] This promise, however, has not come to fruition due to propensity of fluorofullerenes for hydrolysis. Research of fluorination of fullerenes has contributed to the basic understanding of chemical reactivity of nanocarbons, especially, in radical reactions. Overall, there are more fluorinated fullerenes than any other halogenated or hydrogenated fullerenes. Small size of F atom, its high reactivity, relative strength of C-F bond compared to C-Hal or C-H bonds, and relative thermal and environmental stability are among the major reasons of the existence of large libraries of well-characterized fluorinated fullerenes.[2] The latter include not only products of direct addition of F atoms to C(C60) atoms, i.e., C60F2n, but also numerous derivatives with fluorine-containing moieties, i.e., C60(RF)n.[3]
Exploration of applications of various classes of fluorinated fullerene materials in organic optoelectronics and biomedical research that was carried out by the CSU group and collaborators in the past decade will be critically overviewed by the author.
Partial support from NSF (CHE-2153922) is acknowledged.
1. H.W. Kroto, J.R. Heath, S.C. O’Brien, R.F. Curl and R.E. Smalley, Nature 318 (1985) 162.
2. O.V. Boltalina and S.H. Strauss (2014) Fluorofullerenes. In Dekker Encyclopedia of Nanosci. and Nanotech., CRC Press, Seven Volume Set, 1436.
3. O. V. Boltalina, A. A. Popov, I. V. Kuvychko, N. B. Shustova, S. H. Strauss, Chem. Rev. (2015) 115, 1051.
(Invited) Ultrafast Excited Electron Relaxation in Triply Fused Ni(II) Porphyrin-Nanographene Conjugates for Energy Conversion
Authors: Cabanillas Gonzalez Juan Ramon 
Published: August 2024

Porphyrins are appealing building blocks for solar energy applications, although their photosensitization capability is limited by their large optical energy gap, resulting in a mismatch in absorption for efficient harvesting of the solar spectrum. Porphyrin π-extension by edge-fusing with nanographenes can be employed to narrow their optical energy gap, enabling the development of porphyrin-based panchromatic dyes with an optimized energy onset for solar energy conversion in dye-sensitized solar fuel and solar cell configurations. Metalloporphyrin-nanographene conjugates based on open-shell transition metals, such as Ni(II), exhibit panchromatic absporption covering the entire visible and part of the near-IR spectral range. Dispite this interesting property, they exhibit fast excited-state electronic relaxation across the Ni d levels, which hampers harnessing photoexcited electrons to trigger photophysical or photochemical reactions. In this work, we shed light into the underlying mechanism behind fast non-radiative relaxation in these systems. Variable temperature transient absorption and global fit analysis are combined with time-dependent density functional theory to produce a picture of the relevant excited states and underlying relaxation pathways in the conjugates. At room temperature, photoexcitation to the lowest S1* energy level is followed by vibrational cooling in 1-2 ps, and intersystem crossing in > 10 ps, setting a short temporal window wherein a small fraction of relaxed singlets decay to the ground state. Following intersystem crossing and triplet internal conversion, triplets relax rapidly to the ground state (S0) in few tens of picoseconds. By performing measurements at low temperature, we provide evidences for the interplay of a lowest terminal triplet level with > 1 ns lifetime which acts as a bottleneck, and a sloped conical intersection to S0* which is thermally accessible at room temperature from the former energy level. The overall triplet decay is dictated by the contributions that fall along these two photophysical branches. This observation bears significance in understanding how nanographene functionalization leads to a profound effect, opening avenues for potential applications in Optoelectronics and related fields.
[1] Garcia-Orrit, S., Vega-Mayoral, V., Chen, Q., Serra, G., Paternò, G. M., Cánovas, E., Narita, A., Müllen, K., Tommasini, M., Cabanillas-González, J., Nanographene-Based Decoration as a Panchromatic Antenna for Metalloporphyrin Conjugates. Small 2023, 19, 2301596.
[2] Garcia-Orrit, S. et al., in preparation

Figure 1
(Invited) Density Functional Theory Study on Molecular Structures of Polyhydroxy Fullerenes
Authors: Xu Yue , Krishna Vijay 
Published: August 2024

Polyhydroxy fullerenes (PHF), also known as fullerenols or fullerols, are water-soluble fullerenes that are being studied for several applications. PHF is usually synthesized by acid or alkali method and is assumed to have only hydroxyl groups. These approaches use uncontrolled oxidation method and it is possible to have unintended functionalization. In fact, few studies have proposed presence of hemi-ketal and carbonyl groups based on NMR, XPS and FTIR studies. However, a complete understanding of their molecular structures is still lacking. Theoretical quantum chemical calculations based on density functional theory (DFT) are commonly used to predict and corroborate vibrational spectrum of molecules. Interestingly, in silico studies thus far have considered fullerenes with only hydroxyl groups with a big mismatch in their calculated vibrational energies and experimental FTIR spectrum.
In this study, we investigated the presence of carbonyl and hemi-ketal functional groups on hydroxylated fullerenes using DFT. We also evaluated the influence of counterions on oxygen-containing functional groups. All DFT calculations were carried out on Gaussian19 with hybrid B3LYP functional and 6-31G(d,p) basis set. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. Furthermore, our theoretical calculations suggest a dynamic nature inherent in these oxygen-containing functional groups residing on the carbon cage of the fullerene structure.
(Invited) Diverse Strategies for Pseudocapacitance in 2D Materials and Beyond
Authors: Lukatskaya Maria 
Published: August 2024

As electronic technology advances, the need in safe and long-lasting energy storage devices that occupy minimum volume arises. Short charging times of several seconds to minutes, with energy densities comparable to those of batteries, can be achieved in pseudocapacitors. These are sub-class of supercapacitors, where capacitance is mediated by fast redox reactions and can enable at least an order of magnitude more energy to be stored than in typical electrical double layer capacitors. Transition metal oxides (e.g. RuO2, MnO2) and conducting polymers (e.g. polyaniline) serve as typical examples. However, these materials are often high in cost and/or suffer from low cycling stability. As a result, the search for new pseudocapacitive materials constitutes an important direction today.
In my talk, I will discuss various strategies to improve the performance metrics of pseudocapacitors, specifically focusing on enhancing capacitance and charging rates. I will primarily discuss the electrochemical behavior of layered materials, such as 2D transition metal carbides (MXenes) and 2D pi-conjugated conductive metal-organic frameworks, with a strong emphasis on understanding the mechanisms of charge storage and the various factors influencing electrochemical performance. Additionally, I will explore the role of cation intercalation in layered MXenes as a means to finely tune their electrochemical responses.