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"Everett, S"
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Engineering Li/Na selectivity in 12-Crown-4–functionalized polymer membranes
by
Dilenschneider, Theodore J.
,
Mukherjee, Sanjoy
,
Warnock, Samuel J.
in
Applied Physical Sciences
,
Aqueous environments
,
Aqueous solutions
2021
Lithium is widely used in contemporary energy applications, but its isolation from natural reserves is plagued by time-consuming and costly processes. While polymer membranes could, in principle, circumvent these challenges by efficiently extracting lithium from aqueous solutions, they usually exhibit poor ion-specific selectivity. Toward this end, we have incorporated host–guest interactions into a tunable polynorbornene network by copolymerizing 1) 12-crown-4 ligands to impart ion selectivity, 2) poly(ethylene oxide) side chains to control water content, and 3) a crosslinker to form robust solids at room temperature. Single salt transport measurements indicate these materials exhibit unprecedented reverse permeability selectivity (∼2.3) for LiCl over NaCl—the highest documented to date for a dense, water-swollen polymer. As demonstrated by molecular dynamics simulations, this behavior originates from the ability of 12-crown-4 to bind Na⁺ ions more strongly than Li⁺ in an aqueous environment, which reduces Na⁺ mobility (relative to Li⁺) and offsets the increase in Na⁺ solubility due to binding with crown ethers. Under mixed salt conditions, 12-crown-4 functionalized membranes showed identical solubility selectivity relative to single salt conditions; however, the permeability and diffusivity selectivity of LiCl over NaCl decreased, presumably due to flux coupling. These results reveal insights for designing advanced membranes with solute-specific selectivity by utilizing host–guest interactions.
Journal Article
Structural Evolution and Transition Dynamics in Lithium Ion Battery under Fast Charging: An Operando Neutron Diffraction Investigation
2021
Fast charging (<15 min) of lithium‐ion batteries (LIBs) for electrical vehicles (EVs) is widely seen as the key factor that will greatly stimulate the EV markets, and its realization is mainly hindered by the sluggish diffusion of Li+. To have a mechanistic understanding of Li+ diffusion within LIBs, in this study, structural evolutions of electrodes for a Ni‐rich LiNi0.6Mn0.2Co0.2O2 (NMC622) || graphite cylindrical cell with high areal loading (2.78 mAh cm−2) are developed for operando neutron powder diffraction study at different charging rates. Via sequential Rietveld refinements, changes in structures of NMC622 and LixC6 are obtained during moderate and fast charging (from 0.27 C to 4.4 C). NMC622 exhibits the same structural evolution regardless of C‐rates. For phase transitions of LixC6, the stage I (LiC6) phase emerges earlier during the stepwise intercalation at a lower state of charge when charging rate is increased. It is also found that the stage II (LiC12) → stage I (LiC6) transition is the rate‐limiting step during fast charging. The LiC12 → LiC6 transition mechanism is further analyzed using the Johnson–Mehl–Avrami–Kolmogorov model. It is concluded as a diffusion‐controlled, 1D phase transition with decreasing nucleation kinetics under increasing chargingrates. Operando neutron diffraction has been used to study the structural evolutions and phase transitions in a LiNi0.6Mn0.2Co0.2O2 (NMC622) || graphite cylindrical cell at different charging rates. The phase transition from LiC12 to LiC6 is a limiting step under fast charging, which is a diffusion‐controlled, 1D process with decreasing nucleation kinetics via the Johnson–Mehl–Avrami–Kolmogorov model.
Journal Article
Social influences on physical activity for establishing criteria leading to exercise persistence
by
Hill, James O.
,
Gist, Nicholas H.
,
Sayer, R. Drew
in
Biology and Life Sciences
,
Criteria
,
Differential equations
2022
Despite well-documented health benefits from exercise, a study on national trends in achieving the recommended minutes of physical activity guidelines has not improved since the guidelines were published in 2008. Peer interactions have been identified as a critical factor for increasing a population’s physical activity. The objective of this study is for establishing criteria for social influences on physical activity for establishing criteria that lead to exercise persistence. A system of differential equations was developed that projects exercise trends over time. The system includes both social and non-social influences that impact changes in physical activity habits and establishes quantitative conditions that delineate population-wide persistence habits from domination of sedentary behavior. The model was generally designed with parameter values that can be estimated to data. Complete absence of social or peer influences resulted in long-term dominance of sedentary behavior and a decline of physically active populations. Social interactions between sedentary and moderately active populations were the most important social parameter that influenced low active populations to become and remain physically active. On the other hand, social interactions encouraging moderately active individuals to become sedentary drove exercise persistence to extinction. Communities should focus on increasing social interactions between sedentary and moderately active individuals to draw sedentary populations to become more active. Additionally, reducing opportunities for moderately active individuals to engage with sedentary individuals through sedentary social activities should be addressed.
Journal Article
Can guided self-help improve the management of binge eating in adults type 2 diabetes? Results of the POSE-D study
2024
People with type 2 diabetes are more likely to experience binge eating than the general population, which may interfere with their diabetes management. Guided Self-Help (GSH) is the recommended treatment for binge eating disorder (1), but there is currently a lack of evidenced treatment for binge eating in individuals living with type 2 diabetes. The aims of this pilot study were to test the feasibility and acceptability of recruiting and delivering a 12-week, online psychological GSH intervention which has been adapted in an earlier study to the needs of adults with T2 diabetes and binge eating (2). The intervention comprises GSH materials presented online in 7-sections delivered over 12-weeks, supported by a trained Guide. In total 22 participants were recruited in a case series design, through GP practices, NHS specialist weight management and diabetes services and via social media. Outcome measures were collected pre and post-intervention and at 12-week follow-up. The primary outcome was the Gormally Binge Eating Scale and secondary outcomes included eating disorder psychopathology, depression, anxiety, quality of life and HBA1C. Following the intervention, we conducted semi-structured interviews with 6 participants and 4 Guides. Data were analysed using a random intercept multi-level model. Results showed at baseline that 67% of the sample met the criteria for moderate to severe binge eating (cut-off (≤17). At post-intervention there was a statistically significant reduction in self- reported binge eating on the Gormally binge eating scale with a reduction in mean score moving from 26.8 to 14.2, (t= -4.181, p < 0.001) and only 9% meeting criteria for binge eating. There were also notable improvements in anxiety, depression and quality of life scores, but not eating disorder psychopathology. In the interviews both Guides and participants found the adapted online platform easy to use and the sessional support sufficient. They highlighted what a large commitment it was and therefore the importance of the Guide and working in ‘partnership’. The intervention appeared particularly suited to ‘stress eaters’, those experiencing ‘severe binge eating’ episodes and physical symptoms of diabetes. As a result of the intervention, participants reported ‘making broader lifestyle changes’, ‘improvements in their diabetes management’ and ‘confidence’. Guides found the training and supervision helpful but reflected on some ‘challenges with engagement’. On ending the intervention, participants requested ‘ongoing support’, such as an optional follow-up appointment and continued access to the materials. In conclusion, the study shows preliminary evidence for online GSH tailored to the needs of individuals with T2D as a promising approach to improving binge eating, diabetes management, mental wellbeing and quality of life, however effectiveness evidence is needed.
Journal Article
Genetic disorders and associated morbidity, mortality, and congenital anomalies in preterm infants born at less than 34 weeks of gestation
2025
Background
Genetic disorders are recognized as key contributors to morbidity, mortality, and congenital anomalies in term infants. However, the rates of diagnosis and association with morbidity, mortality, and congenital anomalies in preterm infants are poorly characterized. We sought to determine rates of diagnosis of genetic disorders in preterm infants and to define the association of genetic disorders with morbidity, mortality, and congenital anomalies.
Methods
This was a multicenter observational cohort study conducted in neonatal intensive care units in the Pediatrix Clinical Data Warehouse. Infants born from 23 to 0/7 to 33 and 6/7 weeks of gestation, admitted to 374 U.S. community and academic neonatal intensive care units from 2000 to 2020 were included. Infants transferred after birth or prior to discharge were excluded. We analyzed diagnosis of genetic disorders; predischarge morbidity (including acute kidney injury, bronchopulmonary dysplasia, necrotizing enterocolitis, sepsis, shock, severe retinopathy, and intracranial hemorrhage); mortality; and presence of congenital anomalies.
Results
Among 323,770 early preterm infants analyzed, 4,196 (1.3%) were diagnosed with one of twenty genetic disorders. Single gene disorders were identified in 2,250 (0.7%) infants, copy number variants in 88 (0.03%) infants, and aneuploidies in 1,885 (0.6%) infants. Morbidity, mortality, and congenital anomalies occurred in 1,319 (31.4%), 566 (13.5%), and 1,041 (24.8%) infants with genetic disorders compared to 77,957 (24.5%), 15,240 (4.7%), and 9,455 (3.0%) infants without genetic disorders. Common aneuploidies accounted for most of these associations. However, morbidity, mortality, and congenital anomalies were also significantly more common in early preterm infants with single gene disorders and pathogenic copy number variants. We did not detect meaningful differences in diagnostic rates of genetic disorders over the study period.
Conclusions
1.3% of early preterm infants were diagnosed with genetic disorders. Genetic disorders were strongly associated with morbidity, mortality, and congenital anomalies. Clinicians should strongly consider genetic evaluation in early preterm infants with morbidity, mortality, or congenital anomalies. Prospective research is needed to determine the true prevalence of genetic disorders in this high-risk population.
Journal Article
Local structure and distortions of mixed methane-carbon dioxide hydrates
by
Cladek, Bernadette R.
,
Keffer, David J.
,
Rawn, Claudia J.
in
639/301/1034/1037
,
639/301/930/12
,
639/4077/4057
2021
A vast source of methane is found in gas hydrate deposits, which form naturally dispersed throughout ocean sediments and arctic permafrost. Methane may be obtained from hydrates by exchange with hydrocarbon byproduct carbon dioxide. It is imperative for the development of safe methane extraction and carbon dioxide sequestration to understand how methane and carbon dioxide co-occupy the same hydrate structure. Pair distribution functions (PDFs) provide atomic-scale structural insight into intermolecular interactions in methane and carbon dioxide hydrates. We present experimental neutron PDFs of methane, carbon dioxide and mixed methane-carbon dioxide hydrates at 10 K analyzed with complementing classical molecular dynamics simulations and Reverse Monte Carlo fitting. Mixed hydrate, which forms during the exchange process, is more locally disordered than methane or carbon dioxide hydrates. The behavior of mixed gas species cannot be interpolated from properties of pure compounds, and PDF measurements provide important understanding of how the guest composition impacts overall order in the hydrate structure.
Natural gas can be collected from hydrate deposits by exchange with CO
2
, but the ensuing mixed hydrates and the path to a complete exchange are not fully understood. Here, computational analyses of neutron pair distribution functions of CH
4
, CO
2
and mixed CH
4
-CO
2
hydrates at 10 K reveal that the behavior of mixed gas species cannot be interpolated from properties of pure compounds.
Journal Article
Synthesis and structural characterization of Ca12Ga14O33
by
McCoy, Sabrina E. A.
,
Salasin, John R.
,
Rawn, Claudia J.
in
639/301
,
639/301/119/1002
,
639/301/299
2020
Ca
12
Ga
14
O
33
was successfully synthesized using a wet chemistry technique to promote the homogenous mixing of the Ca and Ga cations. Rietveld refinements on X-ray and neutron powder diffraction data confirm that the compound is isostructural to Ca
12
Al
14
O
33,
however, with a significantly larger lattice parameter allowing for the cages that result from the framework arrangement to expand. In naturally occurring Ca
12
Al
14
O
33
, the mineral mayenite, these cages are occupied by O
2−
anions, however, experimental studies exchanging the O
2−
anions with other anions has led to a host of applications, depending on the caged anion. The functional nature of the structure, where framework distortions coupled with cage occupants, are correlated to electronic band structure and modifications to the framework could lead to interesting physical properties. The phase evolution was tracked using thermogravimetric analysis and high temperature X-ray diffraction and showed a lower formation temperature for the Ca
12
Ga
14
O
33
analogue compared to Ca
12
Al
14
O
33
synthesized using the same wet chemistry technique. Analyzing both X-ray and neutron powder diffraction using the Rietveld method with two different starting models results in one structural model, with one Ca position and the caged O on a 24
d
special position, being preferred.
Journal Article
The role of cholecystectomy following endoscopic sphincterotomy and bile duct stone removal
2023
Choledocholithiasis is common, with patients usually treated with endoscopic retrograde cholangiopancreatography (ERCP) and subsequent cholecystectomy to remove the presumed source of common bile duct (CBD) stones. However, previous investigations into the management of patients following ERCP have focused on recurrent CBD stones, negating the risks of cholecystectomy. This article appraises the role of cholecystectomy following successful endoscopic clearance of bile duct stones.
Patients undergoing ERCP and CBD clearance for choledocholithiasis at St James's University Hospital January 2015-December 2018 were included. Patients were divided into those who received cholecystectomy and those managed non-operatively. Readmissions, operative morbidity, mortality and treatment costs were investigated.
Eight hundred and forty-four patients received ERCP and CBD clearance with 3.9 years follow-up. Two hundred and nine patients underwent cholecystectomy with 15% requiring complex surgery. Three hundred and seventy-three patients were non-operatively managed. Unplanned readmissions occurred in 15% following ERCP, mostly within two years. There was no difference in readmissions between the two groups. Accounting for the entire patient pathway, non-operative management was less expensive.
The majority of patients do not require readmission following ERCP for CBD stones, and cholecystectomy did not reduce the risk of readmission. Few patients have recurrent CBD stones, but complex biliary surgery is frequently required. Routine cholecystectomy following ERCP needs to be re-evaluated and a more stratified approach to future risk developed.
Journal Article
Large-scale production of magnetic nanoparticles using bacterial fermentation
2010
Abstract
Production of both nano-sized particles of crystalline pure phase magnetite and magnetite substituted with Co, Ni, Cr, Mn, Zn or the rare earths for some of the Fe has been demonstrated using microbial processes. This microbial production of magnetic nanoparticles can be achieved in large quantities and at low cost. In these experiments, over 1 kg (wet weight) of Zn-substituted magnetite (nominal composition of Zn0.6Fe2.4O4) was recovered from 30 l fermentations. Transmission electron microscopy (TEM) was used to confirm that the extracellular magnetites exhibited good mono-dispersity. TEM results also showed a highly reproducible particle size and corroborated average crystallite size (ACS) of 13.1 ± 0.8 nm determined through X-ray diffraction (N = 7) at a 99% confidence level. Based on scale-up experiments performed using a 35-l reactor, the increase in ACS reproducibility may be attributed to a combination of factors including an increase of electron donor input, availability of divalent substitution metal ions and fewer ferrous ions in the case of substituted magnetite, and increased reactor volume overcoming differences in each batch. Commercial nanometer sized magnetite (25–50 nm) may cost $500/kg. However, microbial processes are potentially capable of producing 5–90 nm pure or substituted magnetites at a fraction of the cost of traditional chemical synthesis. While there are numerous approaches for the synthesis of nanoparticles, bacterial fermentation of magnetite or metal-substituted magnetite may represent an advantageous manufacturing technology with respect to yield, reproducibility and scalable synthesis with low costs at low energy input.
Journal Article
A moderated mediation test of personality, coping, and health among deployed soldiers
2012
Our study examines how personality and coping influence soldiers' psychological health among 648 US Army personnel who were at that time deployed in Iraq at the height of an insurgency. Conscientiousness, neuroticism, and extraversion were associated with different coping behaviors, and these were in turn related to psychological distress. Conscientiousness was positively associated with problem-focused coping and negatively with avoidance coping, whereas neuroticism was most positively associated with avoidance coping. Extraversion was positively related to both seeking social support and avoidance coping. As expected, avoidance coping was positively associated with psychological distress. Coping style explained more variance in the relationship between personality and distress among soldiers who perceived higher levels of threat, thus supporting a moderated mediation hypothesis. We discuss implications for facilitating the stress coping of workers who face acute and potentially traumatic stress exposures.
Journal Article