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Impact of Sc-doping on structural, phase purity, and dielectric properties of AlN thin films
Aluminum nitride (AlN) thin films were deposited using RF magnetron sputtering at 150 and 175 W to investigate the impact of sputtering power and scandium (Sc) doping on their structural, phase purity, and dielectric properties. X-ray diffraction analysis confirmed high c-axis orientation for films grown at 175 W (for Al), while x-ray photoelectron spectroscopy core spectra of Al and N elements revealed binding energies at 73.5 and 396.4 eV, respectively, verifying its oxidation state, which indicates the formation of AlN without any oxynitride. Atomic force microscopy substantiated that the film roughness was less than 3 nm, suitable for surface acoustic wave devices. The dielectric constant obtained through capacitance–voltage (C−V) measurements was found to be 7.17 for the optimized AlN film. Furthermore, AlScN thin films with different Sc concentrations were deposited by fixing the optimized Al power at 175 W and varying the Sc power at 60 (AlScN–60) and 90 W (AlScN−90). AlScN–60 exhibited a highly c-axis orientation and phase pure nature, while AlScN–90 showed the formation of unwanted scandium oxide, which was confirmed through x-ray photoelectron spectroscopy. Pristine AlN deposited at 175 W and AlScN–60 samples followed space charge limited conduction (SCLC) mechanism, whereas AlN deposited at 150 W and AlScN–90 exhibited both SCLC and Poole–Frenkel conduction mechanisms. The incorporation of Sc into AlN lattice results in an increase in the dielectric constant, while the leakage current significantly decreases.
Insights from virtual chemistry: Shear and bulk viscosity of organic liquids via molecular simulations
Molecular simulations are important tools for predicting the thermophysical properties of liquids, and a rigorous validation of the model potentials is crucial to ensure their reliability for new applications. In the existing literature on empirical force fields, there is an obvious lack of data for shear and bulk viscosity. While experimental or model values for shear viscosity are widely available and represent an excellent benchmark, bulk viscosity is more challenging to measure, and experimental values are available for only a handful of liquids. Here, we present an analysis of both shear and bulk viscosity, calculated from molecular dynamics simulations via the Green–Kubo relations, for over 140 small molecular Newtonian liquids from the Virtual Chemistry database. Therefore, we provide a comprehensive reference for these transport properties for the popular optimized potential for liquid simulations (OPLS) force field and the generalized Amber force field (GAFF).
Formation of the 15 Å phase as the most expanded hydrated mineral in cold subduction zone
Numerical investigation on the penetration process of steel casings in riprap environment of estuarine mudflats
Thermal effect of near-infrared lasers in single nanoparticle whispering-gallery-mode sensing in aqueous solution
Optical whispering-gallery mode (WGM) sensors have been developed for the detection of clinically relevant biomolecules, detection of materials in different phases and forms, and field-based sensing applications. The optical resonance inside a microsphere cavity, induced by total internal reflection that excites the WGM, and the small refractive index change caused by the loading of nano-scale particles, results in a detectable shift of the resonant dip. We confirmed this mode volume-dependent reactive sensing mechanism by using SiO2 nanoparticles and obtained the optimal microsphere radius by verifying the wavelength shift through controlling the size of the microsphere. By comparing the simulated and experimental results, the sensitivity of the resonant sensing is approaching the single nanoparticle regime. Then, a microfluidic system was built to investigate the influence of the resonant dip shift caused by the rise of the water temperature through the heating effect of near-infrared lasers. The results showed that the microfluidic system could greatly suppress the thermal effect even using a 1550 nm laser. Furthermore, when using the microfluidic system, the WGM sensing using the 1550 nm laser shows higher stability than that using the 852 nm laser. This work offers a possibility for the WGM sensing in aqueous solutions with the c-band lasers.
Structure and supramolecular organization of silver nitrate modified epoxy or amino terminated liquid oligoethers
The behavior of silver nitrate in non-aqueous liquid oligomeric media—aromatic and aliphatic diglycidyl ethers and aliphatic diamine—has been investigated. By employing UV–visible spectrophotometry and dynamic light scattering, it has been shown that in diglycidyl oligomers, regardless of the nature of the monomeric unit, the formation of silver nanoparticles occurs, and the kinetics of this process has been studied. At the same time, in the medium of aliphatic diamine, the reduction of silver ions is absent, indicating the formation of a complex compound. XANES and EXAFS confirmed the formation of such a complex, established the probable coordination number of silver equal to three, and characterized the nearest atomic environment of silver. The SAXS results indicate the formation of complexes of extended conformation environment associated oligodiamine molecules, which favors the formation of an extended network of associates. The SAXS data were used to calculate the composition of the mixture of complexes and associates of diamine molecules for a saturated solution of silver nitrate in diamine. The results of this work will be used to develop new oligomer–silver nanocomposites with unique optical and bactericidal properties.
Learning lessons from nano-medicine to improve the design and performances of nano-agrochemicals
Investigating whether smoking and alcohol behaviours influence risk of type 2 diabetes using a Mendelian randomisation study
Abstract Previous studies suggest that smoking and higher alcohol consumption are associated with greater type 2 diabetes (T2D) risk. However, studies examining whether this reflects causal relationships are limited and often do not consider continuous glycaemic traits. We conducted both two-sample and one-sample Mendelian randomisation (MR), using publicly available GWAS data and UK Biobank data, respectively, to examine the potential causal effects of lifetime smoking index (LSI) and alcoholic drinks per week (DPW) on T2D and continuous traits (fasting glucose, fasting insulin and glycated haemoglobin, HbA1c). Two-sample MR results suggested possible causal effects of higher LSI on T2D risk (OR per 1SD higher LSI: 1.42, 95% CI 1.22 to 1.64); however, sensitivity analyses did not consistently support this finding. There was no robust evidence that higher DPW influenced T2D risk (OR per 1 SD higher log-transformed DPW: 1.04, 95% CI 0.40 to 2.65). There was evidence of a potential causal effect on higher fasting glucose (difference in mean fasting glucose in mmol/l per 1SD higher log-transformed DPW: 0.34, 95% CI 0.09 to 0.59), though, this was attenuated when accounting for body mass index (BMI), suggesting BMI confounding might explain the potential effect. One-sample MR results suggested a possible causal effect of higher DPW on T2D risk (OR per 1 SD higher log-transformed DPW: 1.71, 95% CI 1.24 to 2.36), but lower HbA1c levels (difference in mean SD of log transformed HbA1c (mmol/mol) per 1 SD higher log-transformed DPW: −0.07, 95% CI −0.11 to −0.02). Our results suggest effective public health interventions to prevent and/or reduce smoking and alcohol consumption are unlikely to reduce T2D prevalence.
A method of detecting magnetic interaction in the quantum spin liquid material NaYbSe2 through magnetic dilution
Quantum spin liquid (QSL) holds important application prospects in the realm of quantum computing, and the precise knowledge of magnetic interaction is essential for understanding the magnetism of QSL materials. Here, we report a method of detecting the magnetic interactions in the triangular-lattice QSL candidate NaYbSe2 through magnetic dilution. The single crystals of NaYb0.02Lu0.98Se2 were grown and they maintain the same crystal structure (space group R-3m) as NaYbSe2. Magnetization steps were observed at Hc = 31 kOe for H//ab and Hc = 53 kOe for H//c in the magnetization curves at 0.39 K, suggesting the formation of nearly isolated antiferromagnetic Yb–Yb dimers. Fitting the dimer magnetization curves yields anisotropic exchange parameters of J⊥/kB ≈ −6.15 K and Jz/kB ≈ −2.14 K and an average exchange of Jav/kB = −6.44 K. Since NaYb0.02Lu0.98Se2 exhibits similar g-factor anisotropy, comparable Yb–Yb bond length, and Yb–Se–Yb superexchange angle to NaYbSe2, these exchange parameters can be viewed as the values of NaYbSe2.
Enhanced photoisomerization with hybrid metallodielectric cavities based on mode interference
The ability to control chemical reactions by coupling organic molecules to confined light in a cavity has recently attracted much attention. While most previous studies have focused on single-mode photonic or plasmonic cavities, here we investigate the effect of hybrid metallodielectric cavities on photoisomerization reactions. Hybrid cavities, which support both photonic and plasmonic modes, offer unique opportunities that arise from the interplay between these two distinct types of modes. In particular, we demonstrate that interference in the spectral density due to a narrow photonic mode and a broad plasmonic mode that are coupled to each other enables hybrid cavities to provide an energy-selective Purcell effect. This effect enhances electronic relaxation only to the desired molecular geometry, providing the ability to increase the yield of photoisomerization reactions. As a test case, we study the asymmetric proton transfer reaction in the electronically excited state of 3-aminoacrolein. Our results, which are robust for a range of realistic cavity parameters, highlight the advantages of hybrid cavities in cavity-induced photochemical processes.
Do actin isoforms have unique functionalities at the protein level?
Distributed blockchain assisted secure data aggregation scheme for risk-aware zone-based MANET
Effect of screening current on the electro-magnetic-force characteristics of high-field no-insulated coils
No-insulation (NI) superconducting coils have emerged as a critical area of research for attaining elevated magnetic fields, owing to their remarkable stability and quench resistance. This study introduces a novel model for azimuthal current characterization, utilizing an enhanced T–A formulation in conjunction with the weak-form finite element method. By establishing a numerical model corresponding to the 32 T double-inserted high-field coil experimental setup at the National High Magnetic Field Laboratory, the influence mechanism of screening current on the electromagnetic and mechanical properties of the coil during excitation is systematically analyzed. The results demonstrated that, compared to the traditional insulated (INS) superconducting coils, the NI coil exhibits reduced screening currents and vertical screening current-induced fields (SCIFs) when the central magnetic field reaches its peak. Notably, the vertical-induced magnetic field plays a dominant role in the distribution of SCIF. The stress–strain analysis obtained employing a subregion-coupled modeling approach reveals that the screening current-induced stress in NI coils is lower than that in INS coils. This finding fully validates the performance advantages of NI coils when operated in ultrahigh field conditions. This study provides new insights and methodologies for the research and application of NI coils in high-field magnet systems.
A cation-gating mechanism for enhanced CO2/N2 separation by porous nanostructure supported ionic liquid membrane
2D porous material supported ionic liquid membranes (SILMs) have demonstrated great potential for CO2 separation and purification, outperforming the original porous material. However, the working mechanism behind their enhanced CO2 selectivity remains unclear. In this study, we have conducted molecular dynamics simulation to investigate the CO2/N2 separation performance and the underlying mechanism of SILMs taking 2D rhombic N-graphdiyne (r-N-GDY) with intrinsic high thermal stability and porous structure covered with 1-butyl-3-methylimidazolium tetrafluoroborate as the representative SILM model. We found that the increase in the SILM thickness can decrease the permeance of CO2 and N2 but can effectively increase the CO2/N2 selectivity. The optimal SILM thickness is found to be 0.6 nm with the permeance reaching 5.7 × 105 GPU for CO2 and the selectivity being up to 25.8, which is 15 times higher than the 1.7 of bare r-N-GDY. This is because CO2 encounters a much lower transmembrane energy barrier than N2. At the molecular level, it is fascinating to observe a cation-gating mechanism, where IL cations play a determinative role in CO2 selectivity. More specifically, the IL cations normally bind at the pore site, like a closed gate for gas. When a CO2 molecule approaches the pore, the IL cation moves away; thus, the gate is opened for CO2 translocation. In contrast, N2 molecules are incapable of opening the cation gate. Such a cation-gating process guarantees the high selectivity of SILMs. This study offers insight into enhanced CO2 selectivity and provides theoretical guidance for designing nanocomposite membranes for gas or water treatment.
New insights on angiosperm crown age based on Bayesian node dating and skyline fossilized birth-death approaches
Mulberry leaves supplementation modulates ruminal and fecal bacterial community and metabolites in growing mutton sheep
Spot crosstalk characterization of microchannel plates
This study investigates the relationship between spot crosstalk performance and microchannel plate (MCP) parameters. MCPs are commonly employed in particle detectors, such as Intensified sCMOS (IsCMOS) or Intensified CCD cameras, to enhance the detection of energetic particles. However, crosstalk, which refers to interference between neighboring spots, can significantly impact the accuracy of spot energy measurements. We developed a three-dimensional micro via array structure simulation model using computer simulation technology to explore this relationship. The simulation utilized the Furman secondary electron emission model and employed the three-dimensional particle-in-cell method to quantitatively calculate spot crosstalk at the MCP output. The validation of our simulation results against experimental data demonstrated good agreement. Our simulations revealed that the dispersion radius and gain predominantly influence spot crosstalk within the microchannel. By judiciously selecting and adjusting operating parameters, the spot crosstalk performance of the MCP can be optimized. This study enhances the understanding of spot crosstalk in MCPs and offers valuable insights for enhancing the performance of spatially resolved particle detectors. Through further research and optimization, we can enhance the accuracy and reliability of measurements in various applications utilizing MCP-based detection systems.
Modeling the Kohn–Sham potential for molecular dissociation with orbital-independent functionals: A proof of principle
We model the Hartree-exchange–correlation potential of Kohn–Sham (KS) density-functional theory adopting a novel strategy inspired by the strictly correlated-electron limit and relying on the exact decomposition of the potential based on the exact factorization formalism. Starting with accurate density and conditional potential for a one-dimensional model of a stretched heteronuclear molecule, we provide a proof-of-principle example of an approximation that accurately reproduces the step of the exact KS potential without resorting to the KS orbitals, virtual or occupied. We also test our strategy using the approximate conditional potentials corresponding to the strictly correlated-electron and the exact-exchange functionals. The results are encouraging in that the initial approximations are modified in the qualitatively correct way: decreasing correlation in the former and increasing it in the latter.