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Physical Chemistry Chemical Physics :... Jul 2024The present investigation fits the reaction kinetics of a lithium-sulfur (Li-S) battery with polar electrolyte employing a novel two-phase continuum multipore model. The...
The present investigation fits the reaction kinetics of a lithium-sulfur (Li-S) battery with polar electrolyte employing a novel two-phase continuum multipore model. The continuum two-phase model considers processes in both the liquid electrolyte phase and the solid precipitates phase, where the diffusion coefficients of the Li ions in a solvent-softened solid state are determined from molecular dynamics simulations. Solubility experiments yield the saturation concentration of sulfur and lithium sulfides in the polar electrolyte employed in this study. The model describes the transport of dissolved molecular and ion species in pores of different size in solvated or desolvated form, depending on pore size. The Li-S reaction model in this study is validated for electrolyte 1 M LiPF in EC/DMC. It includes seven redox reactions and two cyclic non-electrochemical reactions in the cathode, and the lithium redox reaction at the anode. Electrochemical reactions are assumed to take place in the electrolyte solution or the solid state and cyclic reactions are assumed to take place in the liquid electrolyte phase only. The determination of the reaction kinetics parameters takes place fitting the model predictions with experimental data of a cyclic voltammetry cycle with UV-vis spectroscopy.
PubMed: 38958556
DOI: 10.1039/d4cp02061h -
Chaos (Woodbury, N.Y.) Jul 2024Spin chains are correlated quantum models of great interest in quantum systems and materials exhibiting quasi-one-dimensional magnetic properties. Here, we review...
Spin chains are correlated quantum models of great interest in quantum systems and materials exhibiting quasi-one-dimensional magnetic properties. Here, we review results on quantum problems associated with spin chains that are beyond the usual spinon paradigm. Alternatively, we use a representation valid in the thermodynamic limit, N→∞, in terms of the N spin-1/2 physical spins of the spin-1/2XXZ chain in its whole Hilbert space. It was originally introduced for the isotropic point in Carmelo et al. [Phys. Rev. B 92, 165133 (2015)], co-authored by David, and more recently extended to spin anisotropies Δ>1 in Carmelo et al. [Phys. Rev. Res. 5, 043058 (2023)] and J. M. P. Carmelo and P. D. Sacramento [Nucl. Phys. B 974, 115610 (2022); Nucl. Phys. B 997, 116385 (2023) (Corrigendum)]. The physical-spins representation accounts for the spin-1/2XXZ chain's continuous SUq(2) symmetry parameterized by q=Δ+Δ2-1∈]1,∞] and associated with q-spin Sq. Specifically, in this review we consider two quantum problems that are beyond the spinon representation: (a) Spin Bethe strings of length n that have no spinon representation, contribute to the dynamical properties of the spin-1/2XXZ chain with anisotropy Δ>1 and for n=1,2,3 were experimentally identified and realized in the zigzag materials SrCo2V2O8 and BaCo2V2O8; (b) The spin stiffness associated with ballistic spin transport at arbitrary finite temperature, which involves a huge number of energy eigenstates, many of which are generated in the thermodynamic limit from ground states by an infinite number of elementary processes. As found in Carmelo et al. [Phys. Rev. Res. 5, 043058 (2023)] and J. M. P. Carmelo and P. D. Sacramento [Nucl. Phys. B 974, 115610 (2022); Nucl. Phys. B 997, 116385 (2023) (Corrigendum)], the use of the continuous SUq(2) symmetry reveals that for anisotropy Δ>1 the Bethe strings of length n=1,2,3,… describe a number n of physical-spins Sq=0 singlet pairs that for n>1 are bound within a Sq=0 singlet configuration. Their contribution to the spin dynamical structure factor of both the spin-1/2XXZ chain in a longitudinal magnetic field and the spin chains in SrCo2V2O8 is one of the issues addressed in this paper. In addition, the SUq(2) symmetry imposes that only 2Sq out of the N physical spins are the spin carriers. We also review recent results of J. M. P. Carmelo and P. D. Sacramento ["Diffusive spin transport of the spin-1/2 XXZ chain in the Ising regime at zero magnetic field and finite temperature," (submitted) (2024)] concerning the vanishing of the contributions to finite-temperature ballistic spin transport at zero magnetic field. Within the physical-spins representation, this merely follows from the absolute value of the elementary spin currents carried by the M=2Sq spin carriers of all finite-Sq states that contribute to the spin stiffness being finite. Finally, we discuss deviations of the zigzag materials BaCo2V2O8 and SrCo2V2O8 from the one-dimensional physics described the spin-1/2XXZ chain due to selective interchain couplings.
PubMed: 38958539
DOI: 10.1063/5.0204689 -
Spatially characterized pseudo-perfect diffuseness via finite-degree spherical harmonic diffuseness.JASA Express Letters Jul 2024Perfectly diffuse sound fields play an important role in architectural acoustics and there are established theoretical characterizations of perfect diffuseness. Although...
Perfectly diffuse sound fields play an important role in architectural acoustics and there are established theoretical characterizations of perfect diffuseness. Although sound fields in real rooms are diffuse to some extent, they are not perfectly diffuse, and therefore theories are required to describe pseudo-perfectly diffuse sound fields. Here, we aim to spatially characterize pseudo-perfect diffuseness via directional characterization of that, finite-degree spherical harmonic diffuseness. Our results show that finite-degree diffuse sound fields yield local spatial diffuseness, suggesting that spatial pseudo-perfect diffuseness is characterized using the effective radius of diffuseness.
PubMed: 38958526
DOI: 10.1121/10.0026466 -
Nano Letters Jul 2024Piwi-interacting RNAs (piRNAs) are small noncoding RNAs that repress transposable elements to maintain genome integrity. The canonical catalytic hairpin assembly (CHA)...
Piwi-interacting RNAs (piRNAs) are small noncoding RNAs that repress transposable elements to maintain genome integrity. The canonical catalytic hairpin assembly (CHA) circuit relies on random collisions of free-diffused reactant probes, which substantially slow down reaction efficiency and kinetics. Herein, we demonstrate the construction of a spatial-confined self-stacking catalytic circuit for rapid and sensitive imaging of piRNA in living cells based on intramolecular and intermolecular hybridization-accelerated CHA. We rationally design a 3WJ probe that not only accelerates the reaction kinetics by increasing the local concentration of reactant probes but also eliminates background signal leakage caused by cross-entanglement of preassembled probes. This strategy achieves high sensitivity and good specificity with shortened assay time. It can quantify intracellular piRNA expression at a single-cell level, discriminate piRNA expression in tissues of breast cancer patients and healthy persons, and in situ image piRNA in living cells, offering a new approach for early diagnosis and postoperative monitoring.
PubMed: 38958407
DOI: 10.1021/acs.nanolett.4c02230 -
Brazilian Journal of Biology = Revista... 2024The current study evaluates the antibacterial activity of Camponotus compressus (Hymenoptera: Formicidae) body crude extracts. The increasing antibiotic resistance of...
The current study evaluates the antibacterial activity of Camponotus compressus (Hymenoptera: Formicidae) body crude extracts. The increasing antibiotic resistance of bacteria has prompted the world to turn its attention towards insects in the search for new sources of antibacterial compounds. The body crude extract obtained with different solvents were tested against both Gram positive (Staphylococcus aureus, Bacillus subtilis) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae). Standard disc diffusion method was used to perform the activity. The extracts of C. compressus were investigated for their effectiveness against all resistant pathogenic bacteria. Staphylococcus aureus was found to be the most susceptible, exhibiting a high average growth inhibition, while Bacillus subtilis showed a lower average growth inhibition zone. Our findings regarding the inhibitory effect of C. compressus extracts show the presence of a broad-spectrum antibacterial compound. This will be helpful in the search for novel natural antibiotics against robust pathogenic bacterial strains.
Topics: Animals; Anti-Bacterial Agents; Gram-Negative Bacteria; Gram-Positive Bacteria; Microbial Sensitivity Tests; Ants; Complex Mixtures
PubMed: 38958299
DOI: 10.1590/1519-6984.284085 -
The Journal of Antimicrobial... Jul 2024Nasal colonization of two preterm infants in our neonatal ICU by Acinetobacter junii carrying the blaOXA-58 carbapenem resistance gene was demonstrated.
BACKGROUND
Nasal colonization of two preterm infants in our neonatal ICU by Acinetobacter junii carrying the blaOXA-58 carbapenem resistance gene was demonstrated.
OBJECTIVES
To study whether the two isolates were identical and to investigate the hypotheses of cross-transmission.
METHODS
Antibiotic susceptibility tests of the two isolates were performed by standard diffusion and the MICs of carbapenems determined by the MIC-gradient strip method. The blaOXA-58 gene was detected by PCR. Isolates were compared using SNP analysis performed after WGS. The timelines of the two cases were determined based on the investigations and the study of the patients' records.
RESULTS
The two isolates corresponded to the same strain, with case 1 being the index case, demonstrating cross-transmission to case 2.
CONCLUSIONS
Acquisition of the strain was likely due to the recent carbapenem treatment of case 1 and cross-transmission due to the high amount of care administered to the two preterm infants. This is the first description of cross-transmission of A. junii carrying the blaOXA-58 gene.
PubMed: 38958235
DOI: 10.1093/jac/dkae180 -
Chemistry (Weinheim An Der Bergstrasse,... Jul 2024Because of its high specific capacity and superior rate performance, porous carbon is regarded as a potential anode material for lithium-ion batteries (LIBs). However,...
Because of its high specific capacity and superior rate performance, porous carbon is regarded as a potential anode material for lithium-ion batteries (LIBs). However, porous carbon materials with wide pore diameter distributions suffer from low structural stability and low electrical conductivity during the application process. During this study, the calcium carbonate nanoparticle template method is used to prepare coal tar pitch-derived porous carbon (CTP-X). The coal tar pitch-derived porous carbon has a well-developed macroporous-mesoporous-microporous hierarchical porous network structure, which provides abundant active sites for Li+ storage, significantly reduces polarization and charge transfer resistance, shortens the diffusion path and promotes the rapid transport of Li+. More specifically, the CTP-2 anode shows high charge capacity (496.9 mAh g-1 at 50 mA g-1), excellent rate performance (413.6 mAh g-1 even at 500 mA g-1), and high cycling stability (capacity retention rate of about 100% after 1,000 cycles at 2 A g-1). The clean and eco-friendly large-scale utilization of coal tar pitch will facilitate the development of high-performance anodes in the field of LIBs.
PubMed: 38958147
DOI: 10.1002/chem.202400189 -
Journal of the American Heart... Jul 2024Iodine-meta-iodobenzylguanidine scintigraphy is useful for assessing cardiac autonomic dysfunction and predict outcomes in heart failure (HF). The relationship of...
BACKGROUND
Iodine-meta-iodobenzylguanidine scintigraphy is useful for assessing cardiac autonomic dysfunction and predict outcomes in heart failure (HF). The relationship of cardiac sympathetic function with myocardial remodeling and diffuse fibrosis remains largely unknown. We aimed to evaluate the cardiac sympathetic function of patients with HF and its relation with myocardial remodeling and exercise capacity.
METHODS AND RESULTS
Prospectively enrolled patients with HF (New York Heart Association class II-III) were stratified into HF with preserved left ventricular ejection fraction [LVEF] ≥45%) and reduced LVEF. Ventricular morphology/function and myocardial extracellular volume (ECV) fraction were quantified by cardiovascular magnetic resonance, global longitudinal strain by echocardiography, cardiac sympathetic function by heart-to-mediastinum ratio from iodine-meta-iodobenzylguanidine scintigraphy. All participants underwent cardiopulmonary exercise testing. The cohort included 33 patients with HF with preserved LVEF (LVEF, 60±10%; NT-proBNP [N-terminal pro-B-type natriuretic peptide], 248 [interquartile range, 79-574] pg/dL), 28 with HF with reduced LVEF (LVEF, 30±9%; NT-proBNP, 743 [interquartile range, 250-2054] pg/dL) and 20 controls (LVEF, 65±5%; NT-proBNP, 40 [interquartile range, 19-50] pg/dL). Delayed (4 hours) iodine-meta-iodobenzylguanidine heart-to-mediastinum ratio was lower in HF with preserved LVEF (1.59±0.25) and HF with reduced LVEF (1.45±0.16) versus controls (1.92±0.24; <0.001), and correlated negatively with diffuse fibrosis assessed by ECV (=-0.34, <0.01). ECV in segments without LGE was increased in HF with preserved ejection fraction (0.32±0.05%) and HF with reduced left ventricular ejection fraction (0.31±0.04%) versus controls (0.28±0.04, <0.05) and was associated with the age- and sex-adjusted maximum oxygen consumption (peak oxygen consumption); (=-0.41, <0.01). Preliminary analysis indicates that cardiac sympathetic function might potentially act as a mediator in the association between ECV and NT-proBNP levels.
CONCLUSIONS
Abnormally low cardiac sympathetic function in patients with HF with reduced and preserved LVEF is associated with extracellular volume expansion and decreased cardiopulmonary functional capacity.
PubMed: 38958130
DOI: 10.1161/JAHA.124.035264 -
Small (Weinheim An Der Bergstrasse,... Jul 2024Antimony selenide (SbSe) has sparked significant interest in high-efficiency photovoltaic applications due to its advantageous material and optoelectronic properties. In...
Antimony selenide (SbSe) has sparked significant interest in high-efficiency photovoltaic applications due to its advantageous material and optoelectronic properties. In recent years, there has been considerable development in this area. Nonetheless, defects and suboptimal [hk0] crystal orientation expressively limit further device efficiency enhancement. This study used Zinc (Zn) to adjust the interfacial energy band and strengthen carrier transport. For the first time, it is discovered that the diffusion of Zn in the cadmium sulfide (CdS) buffer layer can affect the crystalline orientation of the SbSe thin films in the superstrate structure. The effect of Zn diffusion on the morphology of SbSe thin films with CdZnS buffer layer has been investigated in detail. Additionally, Zn doping promotes forming SbSe thin films with the desired [hk1] orientation, resulting in denser and larger grain sizes which will eventually regulate the defect density. Finally, based on the energy band structure and high-quality SbSe thin films, this study achieves a champion power conversion efficiency (PCE) of 8.76%, with a V of 458 mV, a J of 28.13 mA cm, and an FF of 67.85%. Overall, this study explores the growth mechanism of SbSe thin films, which can lead to further improvements in the efficiency of SbSe solar cells.
PubMed: 38958094
DOI: 10.1002/smll.202403292 -
Small (Weinheim An Der Bergstrasse,... Jul 2024In P2-type layered oxide cathodes, Na site-regulation strategies are proposed to modulate the Na distribution and structural stability. However, their impact on the...
In P2-type layered oxide cathodes, Na site-regulation strategies are proposed to modulate the Na distribution and structural stability. However, their impact on the oxygen redox reactions remains poorly understood. Herein, the incorporation of K in the Na layer of NaNiCuMnO is successfully applied. The effects of partial substitution of Na with K on electrochemical properties, structural stability, and oxygen redox reactions have been extensively studied. Improved Na diffusion kinetics of the cathode is observed from galvanostatic intermittent titration technique (GITT) and rate performance. The valence states and local structural environment of the transition metals (TMs) are elucidated via operando synchrotron X-ray absorption spectroscopy (XAS). It is revealed that the TMO slabs tend to be strengthened by K-doping, which efficiently facilitates reversible local structural change. Operando X-ray diffraction (XRD) further confirms more reversible phase changes during the charge/discharge for the cathode after K-doping. Density functional theory (DFT) calculations suggest that oxygen redox reaction in NaKNiCuMnO cathode has been remarkably suppressed as the nonbonding O 2p states shift down in the energy. This is further corroborated experimentally by resonant inelastic X-ray scattering (RIXS) spectroscopy, ultimately proving the role of K incorporated in the Na layer.
PubMed: 38958092
DOI: 10.1002/smll.202402991