Search

Between March and August 2020, S&P and Moody’s downgraded approximately 25$\%$ of collateral feeding into CLOs and only 2$\%$ of tranche values, with rating actions concentrating in junior tranches. Both S&P and Moody’s modeling indicate that the impacts should have been considerably larger, especially for higher-rated tranches. Neither changes in correlation nor the accumulation of pre-COVID-19 protective cushions can explain the downgrade asymmetry on upper tranches. Instead, CLO managers repositioned their collateral pools to dampen the negative credit shock and rating agencies incorporated qualitative adjustments in their CLO ratings. Important potential policy and market implications from these findings are discussed. Authors have furnished an Internet Appendix, which is available on the Oxford University Press Web site next to the link to the final published paper online.

Crystalline binary mixtures of azobenzene and 4-methoxyazobenzene are reported and form photochemical phase change materials that possess working temperatures in the range of −58 °C to 31 °C.

Efficient photoswitching in the solid-state remains rare, yet is highly desirable for the design of functional solid materials. In particular, for molecular solar thermal energy storage materials high conversion to the metastable isomer is crucial to achieve high energy density. Herein, we report that 4-methoxyazobenzene (MOAB) can be occluded into the pores of a metal-organic framework Zn

Al substitution and subsequent Na excess in Na2Mn3O7 were achieved by a ceramic method, realizing the high-performance Na2.4Al0.4Mn2.6O7 oxygen-redox cathode for Na-ion batteries. A comparison between the two cathodes revealed the role of Al doping.

Funding: This work was supported by Faraday Institution (Grant-FIRG018). We are grateful to Engineering and Physical Sciences Research Council (EPSRC) for the Light Element Facility Grant (EP/T019298/1) and Strategic Equipment Resource Grant (EP/R023751/1). Sodium-ion batteries (NIBs) are emerging as promising devices for energy storage applications. Porous solids, such as metal–organic frameworks (MOFs), are well suited as electrode materials for technologies involving bulkier charge carriers. However, only limited progress has been made using pristine MOFs, primarily due to lack of redox-active organic groups in the materials. In this work a azo-functional MOF, namely UiO-abdc, is presented as an electrode compound for sodium-ion insertion. The MOF delivers a stable capacity (∼100 mA h g−1) over 150 cycles, and post-cycling characterisation validates the stability of the MOF and participation of the azo-group in charge storage. This study can accelerate the realisation of pristine solids, such as MOFs and other porous organic compounds, as battery materials. Publisher PDF

Drug interactions with phospholipid bilayers underpin their behaviour in cell membranes and in liposomal delivery formulations. Liposomal drug delivery in ocular medicine can overcome the physical barriers of the eye and better enable the active molecule to reach its target. Here, Raman and 19 F solid-state NMR spectroscopy are used to characterise the interactions of two ocular corticosteroid drugs, difluprednate (DFP) and fluorometholone (FML), with multilamellar vesicles of phosphatidylcholine (PC). 31 P NMR confirms that the lipid bilayer tolerates a high drug concentration (a drug: lipid molar ratio of 1 : 10). The 19 F NMR spectra of the drugs in lipid bilayers reveal that FML and DFP have different average orientations within the lipid bilayer. Raman spectra of dried lipid films reveal that PC separates from DFP but not from FML, the less lipophilic of the two drugs. This combined approach will assist the design of, and inform the development of, improved liposomal preparations.

Porous carbonaceous materials have many important industrial applications including energy storage, water purification, and adsorption of volatile organic compounds. Most of their applications rely upon the adsorption of molecules or ions within the interior pore volume of the carbon particles. Understanding the behaviour and properties of adsorbate species on the molecular level is therefore key for optimising porous carbon materials, but this is very challenging owing to the complexity of the disordered carbon structure and the presence of multiple phases in the system. In recent years, NMR spectroscopy has emerged as one of the few experimental techniques that can resolve adsorbed species from those outside the pore network. Adsorbed, or "in-pore" species give rise to resonances that appear at lower chemical shifts compared to their free (or "ex-pore") counterparts. This shielding effect arises primarily due to ring currents in the carbon structure in the presence of a magnetic field, such that the observed chemical shift differences upon adsorption are nucleus-independent to a first approximation. Theoretical modelling has played an important role in rationalising and explaining these experimental observations. Together, experiments and simulations have enabled a large amount of information to be gained on the adsorption and diffusion of adsorbed species, as well as on the structural and magnetic properties of the porous carbon adsorbent. Here, we review the methodological developments and applications of NMR spectroscopy and related modelling in this field, and provide perspectives on possible future applications and research directions.

More than 3900 crystalline borates, including borate minerals and synthetic inorganic borates, in addition to a wealth of industrially-important boron-containing glasses, have been discovered and characterized. Of these compounds, 99.9 % contain only the traditional triangular BO3 and tetrahedral BO4 units, which polymerize into superstructural motifs. Herein, a mixed metal K5Ba2(B10O17)2(BO2) with linear BO2 structural units was obtained, pushing the boundaries of structural diversity and providing a direct strategy toward the maximum thresholds of birefringence for optical materials design. 11B solid-state nuclear magnetic resonance (NMR) is a ubiquitous tool in the study of glasses and optical materials; here, density functional theory-based NMR crystallography guided the direct characterization of BO2 structural units. The full anisotropic shift and quadrupolar tensors of linear BO2 were extracted from K5Ba2(B10O17)2(BO2) containing BO2, BO3, and BO4 and serve as guides to the identification of this powerful moiety in future and, potentially, previously-characterized borate minerals, ceramics, and glasses.

Na2Ti3O7 (NTO) is considered a promising anode material for Na‐ion batteries due to its layered structure with an open framework and low and safe average operating voltage of 0.3 V vs. Na+/Na. However, its poor electronic conductivity needs to be addressed to make this material attractive for practical applications among other anode choices. Here, we report a safe, controllable and affordable method using urea that significantly improves the rate performance of NTO by producing surface defects such as oxygen vacancies and hydroxyl groups, and the secondary phase Na2Ti6O13. The enhanced electrochemical performance agrees with the higher Na+ ion diffusion coefficient, higher charge carrier density and reduced bandgap observed in these samples, without the need of nanosizing and/or complex synthetic strategies. A comprehensive study using a combination of diffraction, microscopic, spectroscopic and electrochemical techniques supported by computational studies based on DFT calculations, was carried out to understand the effects of this treatment on the surface, chemistry and electronic and charge storage properties of NTO. This study underscores the benefits of using urea as a strategy for enhancing the charge storage properties of NTO and thus, unfolding the potential of this material in practical energy storage applications., A safe, controllable and affordable method using urea at mild temperatures to synthesise a series of sodium titanate samples with different levels of oxygen vacancies is reported. The formation of oxygen vacancies leads to the reduction of Ti4+ to Ti3+ ions in NTO, together with the formation of hydroxyl groups and a secondary phase, Na2Ti6O13.The urea‐treated samples showed superior electrochemical performance at high rates with respect to pristine NTO.

This paper demonstrates a metal−organic framework (MOF) containing photoswitches within the pores as a hybrid solar thermal fuel (STF) and solid−solid phase-change material (ss-PCM). A series of azobenzene-loaded MOFs were synthesized with the general formula Zn2(BDC)2(DABCO)(AB)x (BDC = 1,4-benzenedicarboxylate, DABCO = 1,4- diazabicyclo[2.2.2]octane, AB = azobenzene, where x = 1.0, 0.9, 0.5, 0.3), herein named 1⊃AB1.0, 1⊃AB0.9, 1⊃AB0.5, and 1⊃AB0.3 respectively. X-ray powder diffraction, solid-state NMR, and density functional theory calculations were used to explore in detail the structural changes of the host framework that take place upon loading with the AB guest molecules. Differential scanning calorimetry measurements reveal a reversible phase change, which is absent from the evacuated framework. Upon irradiation with 365 nm light, 40% of the AB guests converted from the trans to the higher-energy cis isomeric form in 1⊃AB1.0. The energy stored within the metastable cis isomers is released upon heating and balances the endotherm associated with the phase transition. However, the exotherm associated with the phase transition is retained upon cooling, resulting in a net energy release over a full heating−cooling cycle. The maximum energy density is observed for the fully loaded composite 1⊃AB1.0, which releases 28.9 J g−1. In addition, the cis-AB guests in this composite showed negligible thermal reconversion during 4 months at ambient temperature, with an estimated energy storage half-life of 4.5 years. Further development of MOF-based STF-ss-PCMs could lead to applications for solar energy conversion and storage, and thermal management.

Aqueous rechargeable zinc-ion batteries (AZIBs) have drawn enormous attention in stationary applications due to their high safety and low cost. However, the search for new positive electrode materials with satisfactory electrochemical performance for practical applications remains a challenge. In this work, we report a comprehensive study on the use of the vanadium tellurate (NH4)4{(VO2)2[Te2O8(OH)2]}·2H2O, which is tested for the first time as a cathode material in AZIBs.

This paper investigates whether Tether, a digital currency pegged to the U.S. dollar, influenced Bitcoin and other cryptocurrency prices during the 2017 boom. Using algorithms to analyze blockchain data, we find that purchases with Tether are timed following market downturns and result in sizable increases in Bitcoin prices. The flow is attributable to one entity, clusters below round prices, induces asymmetric autocorrelations in Bitcoin, and suggests insufficient Tether reserves before month‐ends. Rather than demand from cash investors, these patterns are most consistent with the supply‐based hypothesis of unbacked digital money inflating cryptocurrency prices.

The adsorption and diffusion of species in activated carbons is fundamental to many processes in catalysis and energy storage. Nuclear magnetic resonance (NMR) gives an insight into the molecular-level mechanisms of these phenomena thanks to the unique magnetic shielding properties of the porous carbon structure, which allows adsorbed (in-pore) species to be distinguished from those in the bulk (ex-pore). In this work we investigate exchange dynamics between ex-pore and in-pore solvent species in microporous carbons using a combination of one-dimensional (1D) and two-dimensional (2D) NMR experiments. We systematically compare the effects of four variables: particle size, porosity, solvent polarity and solvent viscosity to build up a picture of how these factors influence the exchange kinetics. We show that exchange rates are greater in smaller and more highly activated carbon particles, which is expected due to the shorter in-pore‐ex-pore path length and faster diffusion in large pores. Our results also show that in-pore‐ex-pore exchange of apolar solvents is slower than water, suggesting that the hydrophobic chemistry of the carbon surface plays a role in the diffusion kinetics, and that increased viscosity also reduces the exchange kinetics. Our results also suggest the importance of other parameters, such as molecular diameter and solvent packing in micropores.

The commercial success of LiFePO4 in high-power Li-ion batteries is strongly related to its unique ultrahigh-rate charge/discharge performance that permits full charge in less than a minute. Since Li1–xFePO4 (0.05 ≤ x ≤ 0.95) separates into two phases with poor electronic and ionic conduction, this raises questions regarding the structural dynamics of phase separation. In this paper, the transformation of metastable solid solution Li0.6FePO4 into a phase-separated material is studied by analysis of the local and bulk structure. 6Li MAS NMR is used to probe the immediate environment where proximity to Fe3+ results in a significant shift in resonance frequency. Conversely, time-resolved X-ray diffraction (XRD) measurements reveal the transformation kinetics at the unit cell scale. The XRD showed no preferential relaxation along the a, b, and c crystal axes, consistent with the absence of a phase boundary perpendicular to the fast diffusion b axis. Key to the analysis is the preparation of the solid solution, which yields phase-pure samples exhibiting no evidence of the thermodynamically stable LiFePO4 or FePO4 phases. Long-term measurement indicated that after 263 days under an argon atmosphere these samples still exhibited a solid solution fraction > 40%. However, in the presence of an electrolyte, phase separation is significantly more rapid. The results presented support Li et al. model [Nat. Mater.2018, 17, 915], where vehicular lithium transport at the surface determines the rate of phase separation and offers a methodology for studying high-energy-density LiMPO4 systems (M = transition metal) that currently are limited by poor high-rate performance.

Capacitive deionization with porous carbon electrodes is an energy-efficient water treatment technique limited to the remediation of only brackish water due to the severe efficiency drop at high molar strength. Combining experiment and simulation, our work demonstrates the ability of subnanometer pores for permselective ion electrosorption, which enables capacitive deionization for saline media with high concentrations. Molecular dynamics simulations reveal the origin of permselective ion electrosorption in subnanometer pores at high molar strength. Within the subnanometer range, carbon pores with smaller size become more ionophobic and then express a higher ability of permselective ion electrosorption. This can be understood by the effects of the pore size on the microstructure of in-pore water and ions and the nanoconfinement effects on the ion hydration. These findings provide a new avenue for capacitive deionization of saline water (seawater-like ionic strength) to enable the application of highly concentrated saline media by direct use of porous carbons.

Substitution of iron by other transition metals within the remarkably stable olivine framework is of interest considering the expected gain in energy density. However, manganese rich olivine materials suffer from sluggish redox kinetics, leading to electrochemical performances at high current densities which are below expectations. The source of the kinetic limitations is not clear, with multiple processes having been proposed, including low bulk electronic conductivity, structural instability of Mn3+ and a phase transition mechanism. This study employed 7Li MAS NMR relaxation techniques to indirectly probe Li+ dynamics using various stoichiometry of chemically prepared Li x MnyFe1-yPO4 (0 ≤ (x, y) ≤ 1). Focusing on the particle level, the aim was to understand how the different crystal phases, alongside the Mn structural contribution, influence Li+ transport at each stage of the oxidation process. Significantly, the formation of an olivine solid solution with vacancies within this progression gave rise to a faster 7Li transverse relaxation derived from superior Li+ motion.

V.R.S., A.V.D., A.R.A. R.E.M. and J.M.G.are indebted to the Faraday Institution NEXGENNA project (FIRG018) for financial support. We acknowledge the support of the Leverhulme Doctoral Scholarships Programme in “Material Social Futures” (grant number DS-2017-036) for the provision of a PhD studentship to T.W. We acknowledge the support from CCP-NC, funded by the EPSRC (EP/M022501/1), and the UKCP consortium, funded by the EPSRC (EP/P025561/1). K.G. acknowledges the Leverhulme Trust (Research Project Grant Number RPG-2018-395). We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by the EPSRC (EP/P020194). The UK High-Field Solid-State NMR Facility used in this research was funded by EPSRC and BBSRC (EP/T015063/1) as well as, for the1 GHz instrument, EP/R029946/1. Conjugated alkali metal dicarboxylates have recently received attention for applications as organic anode materials in lithium and sodium-ion batteries. In order to understand and optimise these materials, it is important to be able to characterise both the long-range and local aspects of the crystal structure, which may change during battery cycling. Furthermore, some materials can display polymorphism or hydration behaviour. NMR crystallography, which combines long-range crystallographic information from diffraction with local information from solid-state NMR via interpretation aided by DFT calculations, is one such approach, but this has not yet been widely applied to conjugated dicarboxylates. In this work, we evaluate the application of NMR crystallography for a set of model lithium and sodium dicarboxylate salts. We investigate the effect of different DFT geometry optimisation strategies and find that the calculated NMR parameters are not systematically affected by the choice of optimisation method, although the inclusion of dispersion correction schemes is important to accurately reproduce the experimental unit cell parameters. We also observe hydration behaviour for two of the sodium salts, and provide insight into the structure of an as-yet uncharacterised structure of sodium naphthalenedicarboxylate. This highlights the importance of sample preparation and characterisation for organic sodium-ion battery anode materials in particular. Publisher PDF

When fuel gases (H2 and CH4) for fuel cells are produced from fossil fuels and biomass, there is a high possibility of presence of hydrogen sulfide (H2S). Because H2S can poison fuel cells and cause long lasting damage, it is necessary to rigorously remove H2S from fuel gases before use in fuel cells. With the advantages of high efficiency and low energy consumption, desulphurisation via adsorption at low temperatures has attracted the attention of many researchers and has seen recent advances. This review compares the performance of commonly-studied porous materials (metal oxides, activated carbon, zeolites, silica, and metal–organic frameworks (MOF)) that are used for adsorption at low temperatures. Test conditions such as feed gas compositions, feed gas velocity, and breakthrough concentration threshold are considered when comparing the adsorption performance of the materials. High performing materials from each material category are identified and future research directions are discussed.

Transitioning to electrified transport requires improvements in sustainability, energy density, power density, lifetime, and approved the cost of lithium-ion batteries, with significant opportunities remaining in the development of next-generation cathodes. This presents a highly complex, multiparameter optimization challenge, where developments in cathode chemical design and discovery, theoretical and experimental understanding, structural and morphological control, synthetic approaches, and cost reduction strategies can deliver performance enhancements required in the near- and longer-term. This multifaceted challenge requires an interdisciplinary approach to solve, which has seen the establishment of numerous academic and industrial consortia around the world to focus on cathode development. One such example is the Next Generation Lithium-ion Cathode Materials project, FutureCat, established by the UK’s Faraday Institution for electrochemical energy storage research in 2019, aimed at developing our understanding of existing and newly discovered cathode chemistries. Here, we present our perspective on persistent fundamental challenges, including protective coatings and additives to extend lifetime and improve interfacial ion transport, the design of existing and the discovery of new cathode materials where cation and cation-plus-anion redox-activity can be exploited to increase energy density, the application of earth-abundant elements that could ultimately reduce costs, and the delivery of new electrode topologies resistant to fracture which can extend battery lifetime.

A series of azobenzene-loaded metal-organic frameworks were synthesized with the general formula M2(BDC)2(DABCO)(AB)x (M = Zn, Co, Ni, and Cu; BDC = 1,4-benzenedicarboxylate; DABCO = 1,4-diazabicyclo[2.2.2]octane; and AB = azobenzene), herein named M-1⊃ABx. Upon occlusion of AB, each framework undergoes guest-induced breathing, whereby the pores contract around the AB molecules forming a narrow-pore (np) framework. The loading level of the framework is found to be very sensitive to the synthetic protocol and although the stable loading level is close to M-1⊃AB1.0, higher loading levels can be achieved for the Zn, Co, and Ni frameworks prior to vacuum treatment, with a maximum composition for the Zn framework of Zn-1⊃AB1.3. The degree of pore contraction upon loading is modulated by the inherent flexibility of the metal-carboxylate paddlewheel unit in the framework, with the Zn-1⊃AB1.0 showing the biggest contraction of 6.2% and the more rigid Cu-1⊃AB1.0 contracting by only 1.7%. Upon heating, each composite shows a temperature-induced phase transition to an open-pore (op) framework, and the enthalpy and onset temperatures of the phase transition are affected by the framework flexibility. For all composites, UV irradiation causes trans → cis isomerization of the occluded AB molecules. The population of cis-AB at the photostationary state and the thermal stability of the occluded cis-AB molecules are also found to correlate with the flexibility of the framework. Over a full heating-cooling cycle between 0 and 200 °C, the energy stored within the metastable cis-AB molecules is released as heat, with a maximum energy density of 28.9 J g-1 for Zn-1⊃AB1.0. These findings suggest that controlled confinement of photoswitches within flexible frameworks is a potential strategy for the development of solid-solid phase change materials for energy storage.

High purity hydrogen is one of the key factors in determining the lifetime of proton exchange membrane (PEM) fuel cells. However, the current industrial processes for producing high purity hydrogen are not only expensive, but also come with low energy efficiencies and productivity. Finding more cost-effective methods of purifying hydrogen is essential for ensuring wider scale deployment of PEM fuel cells. Among various hydrogen purification methods, adsorption in porous materials and membrane technologies are seen as two of the most promising candidates for the current industrial hydrogen purification methods, with metal organic frameworks (MOF) being particularly popular in research over the last decade. Despite many available reviews on MOFs, most focus on synthesis and production, with few reports focused on performance for hydrogen purification. This review describes the working principle and performance parameters of adsorptive separations and membrane materials and identifies MOFs that have been reported for hydrogen purification. The MOFs are summarised and their performance in separating hydrogen from common impurities (CO2, N2, CH4, CO) is compared systematically. The challenges of commercial application of MOFs for hydrogen purification are discussed. © 2020 Hydrogen Energy Publications LLC

In situ NMR spectroscopy is a powerful technique to investigate charge storage mechanisms in carbon-based supercapacitors thanks to its ability to distinguish ionic and molecular species adsorbed in the porous electrodes from those in the bulk electrolyte. The NMR peak corresponding to the adsorbed species shows a clear change of chemical shift as the applied potential difference is varied. This variation in chemical shift is thought to originate from a combination of ion reorganisation in the pores and changes in ring current shifts due to the changes of electronic density in the carbon. While previous Density Functional Theory calculations suggested that the electronic density has a large effect, the relative contributions of these two effects is challenging to untangle. Here, we use mesoscopic simulations to simulate NMR spectra and investigate the relative importance of ion reorganisation and ring currents on the resulting chemical shift. The model is able to predict chemical shifts in good agreement with NMR experiments and indicates that the ring currents are the dominant contribution. A thorough analysis of a specific electrode/electrolyte combination for which detailed NMR experiments have been reported allows us to confirm that local ion reorganisation has a very limited effect but the relative quantities of ions in pores of different sizes, which can change upon charging/discharging, can lead to a significant effect. Our findings suggest that in situ NMR spectra of supercapacitors may provide insights into the electronic structure of carbon materials in the future.

ObjectiveTo estimate the proportion of presymptomatic transmission of SARS-CoV-2 infection that can occur, and the timing of transmission relative to symptom onset.Setting/designSecondary analysis of international published data.Data sourcesMeta-analysis of COVID-19 incubation period and a rapid review of serial interval and generation time, which are published separately.ParticipantsData from China, the Islamic Republic of Iran, Italy, Republic of Korea, Singapore and Vietnam from December 2019 to May 2020.MethodsSimulations were generated of incubation period and of serial interval or generation time. From these, transmission times relative to symptom onset, and the proportion of presymptomatic transmission, were estimated.Outcome measuresTransmission time of SARS-CoV-2 relative to symptom onset and proportion of presymptomatic transmission.ResultsBased on 18 serial interval/generation time estimates from 15 papers, mean transmission time relative to symptom onset ranged from −2.6 (95% CI −3.0 to –2.1) days before infector symptom onset to 1.4 (95% CI 1.0 to 1.8) days after symptom onset. The proportion of presymptomatic transmission ranged from 45.9% (95% CI 42.9% to 49.0%) to 69.1% (95% CI 66.2% to 71.9%).ConclusionsThere is substantial potential for presymptomatic transmission of SARS-CoV-2 across a range of different contexts. This highlights the need for rapid case detection, contact tracing and quarantine. The transmission patterns that we report reflect the combination of biological infectiousness and transmission opportunities which vary according to context.

In recent years, there has been a resurgence of interest in supercapacitors as high-power electrical energy storage devices with complementary properties to batteries. However, despite their growing applications in new technologies, many fundamental aspects of the charging mechanism remain poorly understood. Recently, some of the fundamental questions about supercapacitors have started to be addressed due to the emergence of NMR spectroscopy as a powerful tool for studying ion behavior in porous carbon electrodes. This chapter provides an overview of NMR methods that have been developed for the study of supercapacitors and reviews recent applications. These span both conventional NMR methods which have been used to study the equilibrium adsorption behavior as well as more advanced in situ methods which have begun to provide insight into working devices.

ObjectivesThe aim of this study was to determine the relative infectiousness of asymptomatic SARS-CoV-2 infected persons compared with symptomatic individuals based on a scoping review of available literature.DesignRapid scoping review of peer-reviewed literature from 1 January to 5 December 2020 using the LitCovid database and the Cochrane library.SettingInternational studies on the infectiousness of individuals infected with SARS-CoV-2.ParticipantsStudies were selected for inclusion if they defined asymptomatics as a separate cohort distinct from presymptomatics and if they provided a quantitative measure of the infectiousness of asymptomatics relative to symptomatics.Primary outcome measuresPCR result (PCR studies), the rate of infection (mathematical modelling studies) and secondary attack rate (contact tracing studies) - in each case from asymptomatic in comparison with symptomatic individuals.ResultsThere are only a limited number of published studies that report estimates of relative infectiousness of asymptomatic compared with symptomatic individuals. 12 studies were included after the screening process. Significant differences exist in the definition of infectiousness. PCR studies in general show no difference in shedding levels between symptomatic and asymptomatic individuals; however, the number of study subjects is generally limited. Two modelling studies estimate relative infectiousness to be 0.43 and 0.57, but both of these were more reflective of the infectiousness of undocumented rather than asymptomatic cases. The results from contact tracing studies include estimates of relative infectiousness of 0, but with insufficient evidence to conclude that it is significantly different from 1.ConclusionsThere is considerable heterogeneity in estimates of relative infectiousness highlighting the need for further investigation of this important parameter. It is not possible to provide any conclusive estimate of relative infectiousness, as the estimates from the reviewed studies varied between 0 and 1.

NMR spectroscopy has recently emerged as a powerful method for studying electrolyte species in microporous carbon electrodes used in capacitive energy storage devices. Key to this approach is the nucleus-independent chemical shift (NICS) which enables adsorbed species to be distinguished from those in the bulk electrolyte. The magnitude of the NICS is well known to be dependent on the distance of the adsorbed species from the carbon surface, and has therefore been used in several studies as a probe of the carbon pore size. However, the NICS can also be influenced by a number of other structural and chemical factors which are not always taken into account. To investigate this, we have carried out a systematic study of the factors influencing the NICS of aqueous electrolyte species adsorbed on polymer-derived activated carbon in the absence of an applied potential. We find that a number of effects arising from both the carbon structure as well as the behaviour and chemical properties of the electrolyte species can contribute to the observed NICS. In turn, the measurement of these effects provides important information about ion behaviour and reveals significant differences in the adsorption behaviour of different ions in the absence of an applied potential. In accordance with several computational studies, we find experimental evidence that the local concentration of spontaneously adsorbed alkali ions decreases with the pore size. This has potential implications for understanding the molecular-level mechanism of charge storage in capacitive devices.

Significance The relative importance of personal traits compared with context for predicting behavior is a long-standing issue in psychology. This debate plays out in a practical way every time an employer, voter, or other decision maker has to infer expected professional conduct based on observed personal behavior. Despite its theoretical and practical importance, there is little academic consensus on this question. We fill this void with evidence connecting personal infidelity to professional behavior in 4 different settings., We study the connection between personal and professional behavior by introducing usage of a marital infidelity website as a measure of personal conduct. Police officers and financial advisors who use the infidelity website are significantly more likely to engage in professional misconduct. Results are similar for US Securities and Exchange Commission (SEC) defendants accused of white-collar crimes, and companies with chief executive officers (CEOs) or chief financial officers (CFOs) who use the website are more than twice as likely to engage in corporate misconduct. The relation is not explained by a wide range of regional, firm, executive, and cultural variables. These findings suggest that personal and workplace behavior are closely related.

The authors would like to thank the ERC (EU FP7 Consolida-tor Grant 614290 ‘‘EXONMR’’) and EPSRC, the Collaborative Computational Project on NMR Crystallography (CCP-NC), via EP/M022501/1 and EP/J501542/1, and the United Kingdom Car-Parrinello Consortium (UKCP) via EP/P022596/1 for computational support. SEA and CJP would like to thank the Royal Society and Wolfson Foundation for merit awards. The Earth’s transition zone, at depths of 410–660 km, while being composed of nominally anhydrous magnesium silicate minerals, may be subject to significant hydration. Little is known about the mechanism of hydration, despite the vital role this plays in the physical and chemical properties of the mantle, leading to a need for improved structural characterization. Here we present an ab initio random structure searching (AIRSS) investigation of semihydrous (1.65 wt % H2O) and fully hydrous (3.3 wt % H2O) wadsleyite. Following the AIRSS process, k-means clustering was used to select sets of structures with duplicates removed, which were then subjected to further geometry optimization with tighter constraints prior to NMR calculations. Semihydrous models identify a ground-state structure (Mg3 vacancies, O1–H hydroxyls) that aligns with a number of previous experimental observations. However, predicted NMR parameters fail to reproduce low-intensity signals observed in solid-state NMR spectra. In contrast, the fully hydrous models produced by AIRSS, which enable both isolated and clustered defects, are able to explain observed NMR signals via just four low-enthalpy structures: (i) a ground state, with isolated Mg3 vacancies and O1–H hydroxyls; (ii/iii) edge-sharing Mg3 vacancies with O1–H and O3–H species; and (iv) edge-sharing Mg1 and Mg3 vacancies with O1–H, O3–H, and O4–H hydroxyls. Thus, the combination of advanced structure searching approaches and solid-state NMR spectroscopy is able to provide new and detailed insight into the structure of this important mantle mineral. Publisher PDF

NMR measurements of 19F chemical shift anisotropy and 1H-19F dipolar couplings provide unprecedented information on the molecular orientations of two fluorine-containing statin drugs within the heterogeneous environment of reconstituted high-density lipoprotein (rHDL) nanoparticles, a drug delivery system under clinical investigation.

A photochromic anil, N-(3,5-di-t-butylsalicylidene)-4-amino-pyridine, has been studied by single-crystal X-ray diffraction, multinuclear magic-angle spinning NMR, and first-principles density functional theory (DFT) calculations. Interpretation of the solid-state NMR data on the basis of calculated chemical shifts confirms the structure is primarily composed of molecules in the ground-state enol tautomer, whereas thermally activated cis-keto and photoisomerised trans-keto states exist as low-level defects with populations that are too low to detect experimentally. Variable temperature 13 C NMR data reveal evidence for solid-state dynamics, which is found to be associated with fast rotational motion of t-butyl groups and 180° flips of the pyridine ring, contrasting the time-averaged structure obtained by X-ray diffraction. Comparison of calculated chemical shifts for the full crystal structure and an isolated molecule also reveals evidence for an intermolecular hydrogen bond involving the pyridine ring and an adjacent imine carbon, which facilitates the flipping motion. The DFT calculations also reveal that the molecular conformation in the crystal structure is very close to the energetic minimum for an isolated molecule, indicating that the ring dynamics arise as a result of considerable steric freedom of the pyridine ring and which also allows the molecule to adopt a favourable conformation for photochromism.

Background The serial interval is the period of time between the onset of symptoms in an infector and an infectee and is an important parameter which can impact on the estimation of the reproduction number. Whilst several parameters influencing infection transmission are expected to be consistent across populations, the serial interval can vary across and within populations over time. Therefore, local estimates are preferable for use in epidemiological models developed at a regional level. We used data collected as part of the national contact tracing process in Ireland to estimate the serial interval of SARS-CoV-2 infection in the Irish population, and to estimate the proportion of transmission events that occurred prior to the onset of symptoms. Results After data cleaning, the final dataset consisted of 471 infected close contacts from 471 primary cases. The median serial interval was 4 days, mean serial interval was 4.0 (95% confidence intervals 3.7, 4.3) days, whilst the 25th and 75th percentiles were 2 and 6 days respectively. We found that intervals were lower when the primary or secondary case were in the older age cohort (greater than 64 years). Simulating from an incubation period distribution from international literature, we estimated that 67% of transmission events had greater than 50% probability of occurring prior to the onset of symptoms in the infector. Conclusions Whilst our analysis was based on a large sample size, data were collected for the primary purpose of interrupting transmission chains. Similar to other studies estimating the serial interval, our analysis is restricted to transmission pairs where the infector is known with some degree of certainty. Such pairs may represent more intense contacts with infected individuals than might occur in the overall population. It is therefore possible that our analysis is biased towards shorter serial intervals than the overall population.

Tapia-Ruiz, Nuria et al., Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid–electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology., The authors gratefully acknowledge RS2E and Alistore-ERI for funding their research into Na-ion batteries. The funding received from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 646433 (NAIADES), the Swedish Research Council, the Swedish Energy Agency (#37671-1), and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS), are all gratefully acknowledged. The many fruitful discussions within ALISTORE-ERI, and especially with M Rosa Palacín, have been most valuable. P J is also grateful for the continuous support from several of the Chalmers Areas of Advance: Materials Science and Energy. Funding from the European Union’s innovation program H2020 is acknowledged: H2020-MSCA-COFUND-2016 (DOC-FAM, Grant Agreement No. 754397). A Ponrouch is grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496).

In the distribution of the Paycheck Protection Program’s (PPP) $803 billion in funds, FinTech lenders began minimally but ramped up their market share to over 80% of originated loans by the end of the program. We examine metrics related to potential misreporting including non-registered businesses, multiple businesses at residential addresses, abnormally high implied compensation per employee, and large inconsistencies in jobs reported with another government program. We assess these four metrics with five additional measures and extensive supporting analysis. FinTech loans exhibit sharp and discontinuous increases in misreporting at maximum loan thresholds and round loan amounts. FinTech loans are more than 3.5 times as likely to be initiated by someone with a criminal background, strongly cluster in industry-county pairs to a degree that is infeasible based on U.S. Census data on establishment counts, and frequently exhibit similar loan features within lender-county pairs. Certain FinTech lenders seem to specialize in questionable loans with more than 40% of their loans experiencing at least one misreporting indicator. Few of these loans have been prosecuted by authorities or repaid. FinTech lenders with the highest misreporting in the first two rounds of the program in 2020 increase both their market share and their misreporting substantially in the third round in 2021. While FinTech lenders likely expand PPP access, this may come at the cost of facilitating fraudulent credit.

The serial interval is the time between symptom onsets in an infector–infectee pair. The generation time, also known as the generation interval, is the time between infection events in an infector–infectee pair. The serial interval and the generation time are key parameters for assessing the dynamics of a disease. A number of scientific papers reported information pertaining to the serial interval and/or generation time for COVID-19. Objective Conduct a review of available evidence to advise on appropriate parameter values for serial interval and generation time in national COVID-19 transmission models for Ireland and on methodological issues relating to those parameters. Methods We conducted a rapid review of the literature covering the period 1 January 2020 and 21 August 2020, following predefined eligibility criteria. Forty scientific papers met our inclusion criteria and were included in the review. Results The mean of the serial interval ranged from 3.03 to 7.6 days, based on 38 estimates, and the median from 1.0 to 6.0 days (based on 15 estimates). Only three estimates were provided for the mean of the generation time. These ranged from 3.95 to 5.20 days. One estimate of 5.0 days was provided for the median of the generation time. Discussion Estimates of the serial interval and the generation time are very dependent on the specific factors that apply at the time that the data are collected, including the level of social contact. Consequently, the estimates may not be entirely relevant to other environments. Therefore, local estimates should be obtained as soon as possible. Careful consideration should be given to the methodology that is used. Real-time estimations of the serial interval/generation time, allowing for variations over time, may provide more accurate estimates of reproduction numbers than using conventionally fixed serial interval/generation time distributions.

Ceramics based around silicon aluminum oxynitrides are of both fundamental structural chemistry and technological interest. Certain oxynitride crystal structures allow very significant compositional variation through extensive Si/N exchange for Al/O, which implies a degree of atomic ordering. In this study, solid-state 29Si MAS NMR and variable field 1D and 2D 27Al MAS NMR measurements are combined with density functional theory calculations of both the structural and NMR interaction parameters for various points across the Y4Si2O7N2-Y4Al2O9 compositional range. This series provides numerous possibilities for significant variation of atomic ordering in the local ditetrahedral (Si,Al)2O7-xNx units. The two slightly structurally inequivalent aluminum sites in Y4Al2O9 are unambiguously assigned to the observed resonances. Computational findings on Y4Si2O7N2 demonstrate that the single observed 29Si NMR resonance covers a range of local inequivalent silicon environments. For the first time, the MAS NMR and neutron diffraction data from the Y4SiAlO8N structure have been directly reconciled, thus establishing aspects of atomic order and disorder that characterize this system. This comparison suggests that, although the diffraction data indicates long-range structural order supporting a highly crystalline character, the short-range information afforded by the solid-state NMR measurements indicates significant atomic disorder throughout the (Si,Al)2O7-xNx units.

More than 3900 crystalline borates, including borate minerals and synthetic inorganic borates, in addition to a wealth of industrially-important boron-containing glasses, have been discovered and characterized. Of these compounds, 99.9 % contain only the traditional triangular BO

ObjectivesThe aim of this study was to conduct a scoping review of estimates of the relative infectiousness of asymptomatic persons infected with SARS-CoV-2 compared with symptomatic individuals.DesignRapid scoping review of literature available until 8thApril 2020.SettingInternational studies on the infectiousness of individuals infected with SARS-CoV-2ParticipantsStudies were selected for inclusion if they defined asymptomatics as a separate cohort distinct from pre-symptomatics and if they provided a quantitative measure of the infectiousness of asymptomatics relative to symptomatics.Primary outcome measuresThe relative number of secondary cases produced by an average primary case, the relative probability of transmitting infection upon contact, and the degree of viral shedding.ResultsVery few studies reported estimates of relative infectiousness of asymptomatic compared with symptomatic individuals. Significant differences exist in the definition of infectiousness. Viral shedding studies in general show no difference in shedding levels between symptomatic and asymptomatic individuals but are likely to be impacted by insufficient statistical power. Two contact tracing studies provided estimates of 0.7 and 1.0, but differences in approach and definition preclude comparison across the two studies. Finally, two modelling studies suggest a relative infectiousness of around 0.5 but one of these was more reflective of the infectiousness of undocumented rather than asymptomatic cases. Importantly, one contact tracing study showing a very low level of infectiousness of asymptomatic was not included in the analysis at this point due difficulties interpreting the reported findings.ConclusionsThe present study highlights the need for additional studies in this area as a matter of urgency. For the purpose of epidemiological modelling, we cautiously suggest that at present, asymptomatics could be considered to have a degree of infectiousness which is about 0.40-0.70 that of symptomatics. However, it must be stressed that this suggestion comes from a very low evidence base and that estimates exist that are close to zero and close to 1.ARTICLE SUMMARYStrengths and limitations of this study-Differences in the definition of infectiousness and a low number of studies estimating this parameter negate the potential to provide a pooled quantitative estimate or relative infectiousness.-The present study highlights the need for additional studies in this area as a matter of urgency.-Several of the studies reviewed are in pre-print stage and are not peer-reviewed.

ObjectivesThe aim of this study was to conduct a rapid systematic review and meta-analysis of estimates of the incubation period of COVID-19.DesignRapid systematic review and meta-analysis of observational research.SettingInternational studies on incubation period of COVID-19.ParticipantsSearches were carried out in PubMed, Google Scholar, Embase, Cochrane Library as well as the preprint servers MedRxiv and BioRxiv. Studies were selected for meta-analysis if they reported either the parameters and CIs of the distributions fit to the data, or sufficient information to facilitate calculation of those values. After initial eligibility screening, 24 studies were selected for initial review, nine of these were shortlisted for meta-analysis. Final estimates are from meta-analysis of eight studies.Primary outcome measuresParameters of a lognormal distribution of incubation periods.ResultsThe incubation period distribution may be modelled with a lognormal distribution with pooled mu and sigma parameters (95% CIs) of 1.63 (95% CI 1.51 to 1.75) and 0.50 (95% CI 0.46 to 0.55), respectively. The corresponding mean (95% CIs) was 5.8 (95% CI 5.0 to 6.7) days. It should be noted that uncertainty increases towards the tail of the distribution: the pooled parameter estimates (95% CIs) resulted in a median incubation period of 5.1 (95% CI 4.5 to 5.8) days, whereas the 95th percentile was 11.7 (95% CI 9.7 to 14.2) days.ConclusionsThe choice of which parameter values are adopted will depend on how the information is used, the associated risks and the perceived consequences of decisions to be taken. These recommendations will need to be revisited once further relevant information becomes available. Accordingly, we present an R Shiny app that facilitates updating these estimates as new data become available.

BackgroundThe transmissibility of SARS-CoV-2 determines both the ability of the virus to invade a population and the strength of intervention that would be required to contain or eliminate the spread of infection. The basic reproduction number, R0, provides a quantitative measure of the transmission potential of a pathogen.ObjectiveConduct a scoping review of the available literature providing estimates of R0for SARS-CoV-2, provide an overview of the drivers of variation in R0estimates and the considerations taken in the calculation of the parameter.DesignScoping review of available literature between the 01 December 2019 and 07 May 2020.Data sourcesBoth peer-reviewed and pre-print articles were searched for on PubMed, Google Scholar, MedRxiv and BioRxiv.Selection criteriaStudies were selected for review if (i) the estimation of R0for SARS-CoV-2 represented either the initial stages of the outbreak or the initial stages of the outbreak prior to the onset of widespread population restriction (“lockdown”), (ii) the exact dates of the study period were provided and (iii) the study provided primary estimates of R0.ResultsA total of 20 R0for SARS-CoV-2 estimates were extracted from 15 studies. There was substantial variation in the estimates reported. Estimates derived from mathematical models fell within a wider range of 1.94-6.94 than statistical models which fell between the range of 2.2 to 4.4. Several studies made assumptions about the length of the infectious period which ranged from 5.8-20 days and the serial interval which ranged from 4.41-14 days. For a given set of parameters a longer duration of infectiousness or a longer serial interval equates to a higher R0. Several studies took measures to minimise bias in early case reporting, to account for the potential occurrence of super-spreading events, and to account for early sub-exponential epidemic growth.ConclusionsThe variation in reported estimates of R0reflects the complex nature of the parameter itself, including the context (i.e. social/spatial structure), the methodology used to estimate the parameter, and model assumptions. R0is a fundamental parameter in the study of infectious disease dynamics, however it provides limited practical applicability outside of the context in which it was estimated, and should be calculated and interpreted with this in mind.STRENGTHS AND LIMITATIONS OF THE SCOPING REVIEWThis study provides an overview of basic reproduction number estimates for SARS-CoV-2 across a range of settings, a fundamental parameter in gauging the transmissibility of an emerging infectious disease.The key drivers of variation in R0estimates and considerations in the calculation of the parameter highlighted across the reviewed studies are discussed.This evidence may be used to help inform modelling studies and intervention strategies.Given the need for rapid dissemination of information on a newly emerging infectious disease, several of the reviewed papers were in the pre-print phase yet to be peer-reviewed.