9 research outputs found
Unlocking the Inaccessible Energy Density of Sodium Vanadium Fluorophosphate Electrode Materials by Transition Metal Mixing
Sodium (Na) vanadium (V) fluorophosphate (NVPF)
is a highly attractive intercalation electrode material due to its high
operation voltage, large capacity, and long cycle life. However, several issues
limit the full utilization of NVPF's energy density: 1) the high voltage
plateau associated with extracting the "third" Na ion in the reaction NVPF
VPF (~4.9 V vs Na/Na) appears above the electrochemical
stability window of most practical electrolytes (~4.5 V); 2) a sudden drop in
Na-ion diffusivity is observed near composition .
Therefore, it is important to investigate the potential substitution of V by
other transition metals in NVPF derivatives, which can access the extraction of
the third Na-ion. In this work, we investigate the partial substitution of V
with molybdenum (Mo), niobium (Nb), or tungsten (W) in NVPF to improve its
energy density. We examine the structural and electrochemical behaviors of
, ,
and across the whole Na composition region of 0
x 4, and at various transition metal substitution levels, namely,
y=0.5, 1.0, 1.5, 2.0 for Mo, and y=1.0, 2.0 for Nb. We find that partial
substitution of 50% V by Mo in NVPF reduces the voltage plateau for extracting
the third Na ion by 0.6 Volts, which enables further Na extraction from
and increases the theoretical gravimetric
capacity from ~128 to ~174 mAh/g. Analysis of the migration barriers for
Na-ions in unveils improved kinetic properties
over NVPF. The proposed material provides an
optimal gravimetric energy density of ~577.3 Wh/kg versus ~507 Wh/kg for the
pristine NVPF, which amounts to an increase of ~13.9%
Harnessing ChatGPT for thematic analysis: Are we ready?
ChatGPT is an advanced natural language processing tool with growing
applications across various disciplines in medical research. Thematic analysis,
a qualitative research method to identify and interpret patterns in data, is
one application that stands to benefit from this technology. This viewpoint
explores the utilization of ChatGPT in three core phases of thematic analysis
within a medical context: 1) direct coding of transcripts, 2) generating themes
from a predefined list of codes, and 3) preprocessing quotes for manuscript
inclusion. Additionally, we explore the potential of ChatGPT to generate
interview transcripts, which may be used for training purposes. We assess the
strengths and limitations of using ChatGPT in these roles, highlighting areas
where human intervention remains necessary. Overall, we argue that ChatGPT can
function as a valuable tool during analysis, enhancing the efficiency of the
thematic analysis and offering additional insights into the qualitative data.Comment: 23 pages, 7 figures, 3 tables, 1 textbo
Neuromuscular disease genetics in under-represented populations: increasing data diversity
Neuromuscular diseases (NMDs) affect ∼15 million people globally. In high income settings DNA-based diagnosis has transformed care pathways and led to gene-specific therapies. However, most affected families are in low-to-middle income countries (LMICs) with limited access to DNA-based diagnosis. Most (86%) published genetic data is derived from European ancestry. This marked genetic data inequality hampers understanding of genetic diversity and hinders accurate genetic diagnosis in all income settings. We developed a cloud-based transcontinental partnership to build diverse, deeply-phenotyped and genetically characterized cohorts to improve genetic architecture knowledge, and potentially advance diagnosis and clinical management.
We connected 18 centres in Brazil, India, South Africa, Turkey, Zambia, Netherlands and the UK. We co-developed a cloud-based data solution and trained 17 international neurology fellows in clinical genomic data interpretation. Single gene and whole exome data were analysed via a bespoke bioinformatics pipeline and reviewed alongside clinical and phenotypic data in global webinars to inform genetic outcome decisions.
We recruited 6001 participants in the first 43 months. Initial genetic analyses ‘solved’ or ‘possibly solved’ ∼56% probands overall. In-depth genetic data review of the four commonest clinical categories (limb girdle muscular dystrophy, inherited peripheral neuropathies, congenital myopathy/muscular dystrophies and Duchenne/Becker muscular dystrophy) delivered a ∼59% ‘solved’ and ∼13% ‘possibly solved’ outcome. Almost 29% of disease causing variants were novel, increasing diverse pathogenic variant knowledge. Unsolved participants represent a new discovery cohort. The dataset provides a large resource from under-represented populations for genetic and translational research.
In conclusion, we established a remote transcontinental partnership to assess genetic architecture of NMDs across diverse populations. It supported DNA-based diagnosis, potentially enabling genetic counselling, care pathways and eligibility for gene-specific trials. Similar virtual partnerships could be adopted by other areas of global genomic neurological practice to reduce genetic data inequality and benefit patients globally
Modeling the effects of salt concentration on aqueous and organic electrolytes
Abstract Understanding the thermodynamic properties of electrolyte solutions is of vital importance for a myriad of physiological and technological applications. The mean activity coefficient γ ± is associated with the deviation of an electrolyte solution from its ideal behavior and may be obtained by combining the Debye-Hückel (DH) and Born (B) equations. However, the DH and B equations depend on the concentration and temperature-dependent static permittivity of the solution ε r (c, T) and the size of the solvated ions r i , whose experimental data is often not available. Here, we use a combination of molecular dynamics and density functional theory to predict ε r (c, T) and r i , which enables us to apply the DH and B equations to any technologically relevant aqueous and nonaqueous electrolyte at any concentration and temperature of interest
Nature of Intramolecular Resonance Assisted Hydrogen Bonding in Malonaldehyde and Its Saturated Analogue
The nature of resonance-assisted
hydrogen bonds (RAHB) is still
subject of an ongoing debate. We therefore analyzed the σ and
Ï€ charge redistributions associated with the formation of intramolecular
hydrogen bonds in malonaldehyde (MA) and its saturated analogue 3-hydroxypropanal
(3-OH) and addressed the question whether there is a resonance assistance
phenomenon in the sense of a synergistic interplay between the σ
and π electron systems. Our quantum chemical calculations at
the BP86/TZ2P level of theory show that the π charge flow is
indeed in line with the Lewis structure as proposed by the RAHB model.
This typical rearrangement of charge is only present in the unsaturated
system, and not in its saturated analogue. Resonance in the π
electron system assists the intramolecular hydrogen bond by reducing
the hydrogen bond distance, and by providing an additional stabilizing
component to the net bonding energy. The σ orbital interaction
plays an important role in the enhanced hydrogen bond strength in
MA as well. However, there is no resonance assistance in the sense
of an interplay between σ charge transfer and π polarization;
σ and π contribute independently from each other
Moxifloxacin Pharmacokinetics, Cardiac Safety, and Dosing for the Treatment of Rifampicin-Resistant Tuberculosis in Children.
BackgroundMoxifloxacin is a recommended drug for rifampin-resistant tuberculosis (RR-TB) treatment, but there is limited pediatric pharmacokinetic and safety data, especially in young children. We characterize moxifloxacin population pharmacokinetics and QT interval prolongation and evaluate optimal dosing in children with RR-TB.MethodsPharmacokinetic data were pooled from 2 observational studies in South African children with RR-TB routinely treated with oral moxifloxacin once daily. The population pharmacokinetics and Fridericia-corrected QT (QTcF)-interval prolongation were characterized in NONMEM. Pharmacokinetic simulations were performed to predict expected exposure and optimal weight-banded dosing.ResultsEighty-five children contributed pharmacokinetic data (median [range] age of 4.6 [0.8-15] years); 16 (19%) were aged <2 years, and 8 (9%) were living with human immunodeficiency virus (HIV). The median (range) moxifloxacin dose on pharmacokinetic sampling days was 11 mg/kg (6.1 to 17). Apparent clearance was 6.95 L/h for a typical 16-kg child. Stunting and HIV increased apparent clearance. Crushed or suspended tablets had faster absorption. The median (range) maximum change in QTcF after moxifloxacin administration was 16.3 (-27.7 to 61.3) ms. No child had QTcF ≥500 ms. The concentration-QTcF relationship was nonlinear, with a maximum drug effect (Emax) of 8.80 ms (interindividual variability = 9.75 ms). Clofazimine use increased Emax by 3.3-fold. Model-based simulations of moxifloxacin pharmacokinetics predicted that current dosing recommendations are too low in children.ConclusionsMoxifloxacin doses above 10-15 mg/kg are likely required in young children to match adult exposures but require further safety assessment, especially when coadministered with other QT-prolonging agents