Browse Articles

Multi-angle study on carbon stock variation and its driving factors in Pingshan County

Enhanced spontaneous emission in proximity of a plasmonic nano-slit antenna

We investigate enhancement in the spontaneous emission (SE) rate of CdSe/ZnS core–shell quantum dots (QDs) by a semi-infinite plasmonic nano-slit antenna. Long Al2O3 filled nano-slits having ∼15 nm width, ∼250 nm height, and >50 μm length in a silver film exhibit strong Fabry–Pérot like resonances associated with gap plasmon modes. For the QDs located on top or in proximity of the nano-slit, we observe ∼15 times enhanced SE relaxation rate compared to the free-space environment. The faster relaxation is attributed to Purcell enhancement resulting from the strong field confinement within the nano-slit and the associated increase in the optical density of states. The experimental results are supported by COMSOL simulations. Our findings demonstrate the ability of the plasmonic nano-slit antenna to strongly enhance the SE rate of emitters in proximity.

A bilinear model for the elastic response of hydrated lipid bilayers under normal pressure difference

The elasticity of phospholipid membranes as a function of hydration was investigated using coarse-grained molecular simulations. Multilamellar membranes consist of two or more lipid bilayers separated by a thin layer of water, a system commonly found in cell membranes that provides surface tension in the alveoli of the lungs and on cartilaginous surfaces of synovial joints. The objective was to quantify the response of such systems to compression in the direction perpendicular to the membranes as a function of the amount of water between the bilayers or hydration of the system. The present study investigated a variety of phospholipids with six levels of hydration found in multilamellar bilayers in biological systems. Our simulations support the existence of a universal behavior of the increase in surface area per lipid as a function of the normal pressure difference, the difference between the pressure applied in the direction normal to the membrane and the pressure applied in the directions parallel to the membrane. Normalizing the surface area per lipid and the pressure difference by their respective values at rupture yields a composite function of two linear regimes for all the hydration levels under investigation. Where possible, a physics-based interpretation of the normalization scales was provided. Although some parameters of the model are determined empirically, the model represents a promising step in continuum modeling of the response of multilamellar lipid membranes as a function of mechanical stress and hydration.

A novel approach to forecasting reproduction numbers of spatiotemporal stochastic epidemic spread using a PDE-based model and real-time infection data

Wiedemann–Franz law and thermoelectric inequalities: Effective <i>ZT</i> and single-leg efficiency overestimation

We derive a thermoelectric inequality in the thermoelectric conversion between the material figure of merit (ZT) and the effective ZT of the module by combining the constant Seebeck coefficient approximation with the Wiedemann–Franz law. In a P–N leg-pair module, the effective ZT lies between the individual ZT values of the P- and N leg materials. In a single-leg module, however, the effective ZT is less than approximately one-third of the leg's ZT because an external wire is necessary to complete the circuit, introducing additional thermal and electrical losses. Multi-dimensional numerical analysis shows that although structural optimization can mitigate these losses, the system efficiency remains limited to below half of the ideal single-leg efficiency. Our findings explain the overestimation of single-leg efficiency and highlight the importance of optimizing the P–N leg-pair module structure. They also underscore the need for thermoelectric leg compatibility, particularly regarding Seebeck coefficients.

Unraveling cation–cation “attraction” in argentophilic interaction in 2,2′-bipydine coordinated silver complex

The nature of argentophilic interaction in the 2,2′-bipyridine-coordinated silver complex, which manifests counterintuitive cation–cation “attraction,” is attributed to ligand stacking and solvation effects in the present article. While charged closed-shell transition metal complexes aggregating spontaneously to form oligomers has long been observed experimentally, the interpretation of the nature of so-called metallophilicity is still ongoing. For the dimer [(2,2′-bpy)2Ag]22+, qualitative electrostatic potential, non-covalent interaction, atoms-in-molecules analyses, and quantitative energy decomposition analysis calculations indicate that the electrostatic repulsion between two like formal charges at silver centers can be overcome by long-range dispersion attraction and short-range electronic correlation from ligands. In addition, delocalizing the net charges on silvers over the whole ligands can decrease electrostatic repulsion of metal centers to stabilize oligomers. The vital role of the screening effect of solvent has also been realized in the bound binding of the title system. Overall, this research highlights the importance of ligand stacking to argentophilicity, while d10–d10 attraction of silver centers presents quite little contribution.

Exploring the role of breastfeeding, antibiotics, and indoor environments in preschool children atopic dermatitis through machine learning and hygiene hypothesis

Abstract The increasing global incidence of atopic dermatitis (AD) in children, especially in Western industrialized nations, has attracted considerable attention. The hygiene hypothesis, which posits that early pathogen exposure is crucial for immune system development, is central to understanding this trend. Furthermore, advanced machine learning algorithms have provided fresh insights into the interactions among various risk factors. This study investigates the relationship between early childhood antibiotic use, the duration of exclusive breastfeeding, indoor environmental factors, and child AD. By integrating machine learning techniques with the hygiene hypothesis, we aim to assess and interpret the significance of these risk factors. In this community-based case–control study with a 1:4 matching design, we evaluated the prevalence of AD in preschool-aged children. Data were collected via questionnaires completed by the parents of 771 children diagnosed with AD, matched with controls based on gender, age, and ethnicity. Univariate analyses identified relevant characteristics, which were further examined using multivariable logistic regression to calculate odds ratios (ORs). Stratified analyses assessed confounders and interactions, while the significance of variables was determined using a machine learning model. Renovating the dwelling during the mother’s pregnancy (OR = 1.50; 95% CI 1.15–1.96) was identified as a risk factor for childhood AD. Additionally, antibiotic use three or more times during the child’s first year (OR = 1.92; 95% CI 1.29–2.85) increased the risk of AD, independent of the parents’ history of atopic disease and the child’s mode of birth. Moreover, exclusive breastfeeding for four months or more (OR = 1.59; 95% CI 1.17–2.17) was identified as a risk factor for AD, particularly in the group without a maternal history of atopic disease. In contrast, having older siblings in the family (OR = 0.76; 95% CI 0.63–0.92) and low birth weight (OR = 0.62; 95% CI 0.47–0.81) were identified as protective factors against AD. Machine learning modeling indicated that the duration of exclusive breastfeeding, having older siblings, low birth weight, and parental history of AD or allergic rhinitis are key predictors of childhood AD. Our findings support the broader interpretation of the hygiene hypothesis. Machine learning analysis highlights the key role of the hygiene hypothesis and underscores the need for future AD prevention and healthcare initiatives focusing on children with a parental history of AD or allergic rhinitis. Moreover, minimizing antibiotic overuse may be essential for preventing AD in children. Further research is necessary to elucidate the impact and mechanisms of exclusive breastfeeding on AD to instruct maternal and child healthcare practices.

Arsenic activation and compensation in single crystal CdTe bilayers

In state-of-the art polycrystalline CdTe photovoltaics, group-V dopant activation is about 2%. Low activation can create electronic defects and lead to recombination and band tail losses. To develop methods to overcome this limitation, dopant activation was systematically investigated using molecular beam epitaxy (MBE) grown single crystal bilayers of As-doped CdTe on undoped CdTe. Results suggest multiple paths for improved As-activation in polycrystalline CdTe-based devices. It was found that the carrier concentration in this MBE material saturated at ∼3 × 1016 cm−3, with high levels (&amp;gt;50%) of As-activation possible. High activation could be achieved with a post-growth activation temperature of ∼450 °C, when the initial doping level was below the saturation level. However, at typical polycrystalline As incorporation levels (&amp;gt;5 × 1016 cm−3), the excess As is inactive or compensating, requiring elevated temperatures (500–600 °C) to achieve high activation. Oxygen in the annealing ambient was detrimental, while the effect of CdCl2 in the ambient is more case-dependent. A 575 °C activation anneal was combined with a 450 °C CdCl2 treatment to better understand the implications for polycrystalline CdTe. Interestingly, on highly doped samples, processes ending with a high temperature step displayed high activation, while those ending at 450 °C significantly reduced the carrier concentration (with or without CdCl2 in the ambient). Low activation can be restored with another high temperature anneal, allowing reproducible toggling between high and low activation based on the final temperature. Photoluminescence revealed the presence of donor–acceptor pairs in the low activation state that appear to be associated with a compensating defect.

Boron-based B3Zn6− alloy cluster as a hybrid between prismatic and sandwich-like structures: Stabilization of a linear B3 chain motif using electronic transmutation

Doping boron clusters with metallic elements can tune the structural, electronic, and bonding properties. We report on the computational design of a zinc-rich D3h (1A1′) B3Zn6− alloy cluster, whose global-minimum structure is a hybrid between prismatic, sandwich-like, and core–shell tubular geometries. The binary cluster features a linear B3 chain along its C3 axis, as well as three lateral Zn–Zn dimers, in which a central B atom is sandwiched by two quasi-planar BZn3 units in an eclipsed form. Chemical bonding analyses show that the B3 chain motif has Lewis-type B–B σ single bonds and a pair of orthogonal three-center two-electron (3c-2e) π bonds, collectively leading to a B–B bond order of two. Stabilizing a boron single chain is scarce in the literature, as is observing a series of double B=B bonds in a monoatomic chain fashion. The triangular pyramid BZn3 units are each in a unique triplet σ2σ*1σ*1 configuration, thus rendering σ aromaticity to the cluster according to the reversed 4n Hückel rule. It is proposed that the alloy cluster can be rationalized using the concept of electronic transmutation, wherein a close chemical analogy to the carbon dioxide (CO2) molecule is established.

Impact of vitamin D deficiency on postoperative outcomes in patients with chronic kidney disease undergoing surgery: a retrospective study

Towards a hypervelocity optical track microparticle accelerator: Theory and initial validation experiments

We propose an optical track accelerator for generating hypervelocity beams of neutral microparticles. In this scheme, projectiles (dielectric microspheres from 1 to 20 μm in diameter) are fed into the hollow core of an optical fiber, stabilized against wall collisions, and accelerated along its length, all using a single laser. Theoretically, efficient light-to-matter momentum transfer (&amp;gt;50% typical, 200% theoretical limit) over a relatively long diffraction-free distance (&amp;gt;10 m) should enable exit velocities exceeding 10 km/s with existing technologies. This novel approach may produce highly directional beams of particles in arbitrary charge states, with uniform sizes and velocities, which can be used to approximate micrometeors in space, terrestrial dust particles, or cold spray powders. Thus, successful demonstration of such an instrument would have application across many high-impact research areas, including but not limited to space debris mitigation, hypersonic ablation, very-low-earth-orbit spaceflight, and additive manufacturing. This architecture takes advantage of rapid concurrent advances in the fields of high-energy lasers and hollow-core optical fibers with high power-handling capability, anticipating their continued growth. In this work, we present an analysis estimating the predicted capabilities of this system, a developmental roadmap for reaching certain velocity milestones, and two sets of experimental results, which validate our models and system concept at low exit velocities of ∼1−10 cm/s.

Active polymer behavior in two dimensions: A comparative analysis of tangential and push–pull models

In this work, we compare the structural and dynamic behavior of active filaments in two dimensions using tangential and push–pull models, including a variant with passive end monomers, to bridge the two frameworks. These models serve as valuable frameworks for understanding self-organization in biological polymers and synthetic materials. At low activity, all models exhibit similar behavior; as activity increases, subtle differences emerge in intermediate regimes, but at high activity, their behaviors converge. Adjusting for differences in mean active force reveals nearly identical behavior across models, even across varying filament configurations and bending rigidities. Our results highlight the importance of force definitions in active polymer simulations and provide insights into phase transitions across varying filament configurations.

A retrospective cohort study assessing medication coverage in patients with prostate cancer prescribed luteinizing hormone releasing hormone (LHRH) agonists in England

Purpose This study aims to assess adherence to luteinising hormone-releasing hormone (LHRH) agonist treatment for prostate cancer (PC) in England, considering formulation-related differences, their impact on overall survival, and the association with changes in prostate-specific antigen (PSA) levels over time. Methods In this retrospective cohort study, utilising primary care data from the Clinical Practice Research Datalink (CPRD) Aurum database linked to Hospital Episode Statistics (HES) and Office for National Statistics (ONS) death registrations, we assessed male patients aged 40 and above diagnosed with PC and prescribed 1-, 3-, or 6-monthly LHRH agonist injections between January 2007 and December 2019. The primary objectives were to measure adherence through proportion of days covered (PDC) and characterize delayed injections, while secondary objectives included assessment of patient demographics, comorbidities, overall survival, and PSA levels. Descriptive statistics were employed, with follow-up restricted to one year for PSA and testosterone measurements due to data availability constraints. Results The study included 32,777 patients with PC receiving LHRH agonists. Most patients (67%) were prescribed 3-monthly formulations, while only 2% received 6-monthly formulations. The mean age of the study population was 74.1 years. Over 80% of patients had at least one comorbidity, with hypertension being the most common. 94% of patients initially prescribed the 3-monthly or 6-monthly regimen remained on their original treatment, in contrast to only 38% for the 1-monthly formulation. Adherence analysis showed that 41.1% of 6-monthly injections were received without delay, compared with 67.9% for the 3-monthly and 77.3% for 1-monthly formulations. A large proportion of patients experienced delays of 14-27 days (32.0%, 33.4%, 54.2%) and over 27 days (39.6%, 48.3%, 46.6%) across the 1-, 3- and 6-monthly formulations respectively. The mean PDC ranged from 90-91% across the three formulation groups, with 89.9%, 84%, and 88.2% achieving ≥ 80% adherence for 3-monthly, 1-monthly, and 6-monthly respectively. Conclusions This study revealed substantial and consistent dosing delays in LHRH agonist prescriptions across all formulations within primary care settings in England. These delays can negatively affect the control of PC, potentially hindering disease management for affected patients. Future research with a larger population, encompassing a larger cohort using the 6-monthly formulation, is essential for a comprehensive evaluation of the impact of LHRH agonist injection delays on PC progression.

Rapamycin mitigates neurotoxicity of fluoride and aluminum by activating autophagy through the AMPK/mTOR/ULK1 pathway in hippocampal neurons and NG108-15 cells

Abstract Our previous studies have confirmed that fluoride combined with aluminum (FA) can induce hippocampal neuron damage in the second-generation offspring (F2) of rats; however, the underlying mechanisms remain unclear. In this study, we established an F2 rat model and an NG108-15 cell model to investigate the potential modes of action. The autophagy of F2 rat hippocampal neurons and NG108-15 cells was assessed using transmission electron microscopy and immunofluorescence/immunocytochemistry kit, respectively. Hippocampal morphology was evaluated via hematoxylin-eosin (HE) staining. We measured mRNA levels of AMPK, mTOR, ULK1, and LC3 using quantitative reverse transcription PCR, and protein expressions were analyzed by Western blotting. Following treatment with rapamycin (Rap) in FA-exposed F2 rats and NG108-15 cells, a small number of primary lysosomes and autophagosomes appeared within hippocampal cells, with HE staining indicating a near-normal restoration of pyramidal cell morphology. The quantity, intensity, and volume of green fluorescent spots in the cytoplasm of NG108-15 cells increased as observed through fluorescence microscopy. The mRNA expressions of AMPK, ULK1, and LC3 were upregulated while mTOR expressions were downregulated in NG108-15 cells. Correspondingly, protein levels for AMPK, p-AMPK, ULK1, p-ULK1 along with the LC3-II/LC3-I ratio increased whereas those for mTOR, p-mTOR and p62 decreased significantly. Similar trends regarding both mRNA and protein expression were noted within the hippocampus of F2 rats as well. Activation of the AMPK/mTOR/ULK1 signaling pathway by Rap enhances FA-induced autophagy thereby mitigating neuronal damage.

Role of interfacial surface anisotropy on liquid grooving at grain boundaries: A phase-field study

Engineering materials are polycrystalline in nature, consisting of numerous single crystals interconnected through a three-dimensional interfacial network known as grain boundaries. Often essential in defining the performance and durability of materials, grain boundaries attract considerable attention during alloy development. Initially, we employ a multi-phase-field model and validate the phenomenon of grain-boundary grooving under isotropic energy conditions, with bulk diffusion as the dominant mass transport mechanism. Subsequently, we investigate the effects of interfacial surface anisotropy and crystal misorientation on groove formation. This present study focuses on the effects of interfacial surface anisotropy and crystal misorientation and, thus, allows us to draw comparisons between the effects of different physical phenomena on the grain-boundary behavior. It is observed that the groove kinetics accelerate as a result of fourfold anisotropy, with groove root deepening proportional to the imposed anisotropic strength. Furthermore, the phase-field results presented here align well with theoretical predictions. In addition, we briefly study on the effect of solid–solid anisotropy on the groove root position. We anticipate that the simulated liquid groove and its precise measurement will serve as important tools for studying the relative energies of grain boundaries.

Modeling entanglement dynamics of molecules interacting with entangled photons through Lindblad master equation approach

This work presents a new approach for simulating the interaction between molecular aggregate systems and multi-modal energy–time entangled light by solving the Lindblad master equation. The density matrix that describes both molecular and photonic states is propagated on a time grid, with excited-state dephasing included via the Lindblad superoperator. Molecular exciton entanglement, induced by entangled photons, is analyzed from the time-evolved density matrix. The calculations are based on a model of a molecular dimer introduced by Bittner et al. [J. Chem. Phys. 152, 071101 (2020)], along with entangled light that is approximated by a finite number of modes. Our results demonstrate that photonic entanglement plays a significant role in influencing molecular exciton entanglement, highlighting the interplay between the photonic and excitonic subsystems in such interactions.

Correction: Comparative analysis of the complete chloroplast genome of Papaveraceae to identify rearrangements within the Corydalis chloroplast genome

Sensitivity analysis of reliability constrained, eco optimal solar, wind, hydrogen storage based islanded power system

Controllable nonlinearities in Landau-quantized graphene

This article presents an exclusive study of the linear and higher-order susceptibilities, as well as the reduction in group index of a weak probe pulse in a three-level Landau-quantized graphene (LQG) system, under the influence of a strong control field, utilizing the phenomenon of electromagnetically induced transparency. The influence of the magnetic field on the higher-order nonlinearities (Kerr, quintic, and septic) leads to observable changes in amplitudes and shifts in probe frequencies. The LQG system exhibits giant values for these nonlinear susceptibilities with χ(3), χ(5), χ(7) reaching magnitudes approximately ∼10−18m3/V2, ∼10−30m5/V4, and ∼10−42m7/V6, respectively, in the mid-infrared range. The magnetic field also induces asymmetric absorption peaks and modifies dispersion profiles. The study also demonstrates a reduction in the group velocity of the probe, under the effect of the magnetic field, by 1000-fold compared to the speed of light in free space. These giant higher-order nonlinearities, coupled with significantly reduced group velocity, suggest that the LQG system is a quick responder, revealing it as an excellent candidate for terahertz modulation. This also highlights the potential of the system as a promising material for generating and detecting coherent nonlinear signals in the mid-infrared range.

An <i>ab initio</i> deep neural network potential to study the effect of density on the thermal decomposition mechanism of FOX-7

Condensed phase explosives typically contain defects such as voids, bubbles, and pores; this heterogeneity facilitates the formation of hot spots and triggers decomposition reaction at low densities. The study of the thermal decomposition mechanisms of explosives at different densities has thus attracted considerable research interest. Gaining a deeper insight into these mechanisms would be helpful for elucidating the detonation processes of explosives. In this work, we developed an ab initio neural network potential for the FOX-7 system using machine learning method. Extensive large-scale (1008 atoms) and long-duration (nanosecond timescale) deep potential molecular dynamics simulations at different densities were performed to investigate the effect of the density on the thermal decomposition mechanism. The results indicate that the initial reaction pathway of the FOX-7 explosives is the cleavage of the C–NO2 bond at different densities, while the frequency of C–NO2 bond cleavage decreases at higher density. Increasing the initial density of FOX-7 significantly increases the reaction rate during the initial decomposition and the formation of final products. However, it leads to a decrease in released heat and has minimal impact on the decomposition temperature. In addition, by analyzing the molecular dynamics trajectories and conducting quantum chemical calculations, we identified two lower-barrier production pathways to produce the CO2 and N2.