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Population and decay of <i>T</i>-shaped ArI2 van der Waals complex ion-pair states studied using two-step, two-color excitation and luminescence spectra measurements
Two-step, two-color populations of T-shaped ArI2(E,vE = 0–2,nE) complexes, accompanied by their electronic predissociation, have been studied. The luminescence spectra of the ion-pair I2(IP,vIP), IP = D′2g, β1g, D0u+, molecules, ArI2(E0g+,vE = 0–2,nE) complexes were measured, and the branching ratios of the I2(IP,vIP) populations and ArI2(E,vE = 0–2,nE) lifetimes were determined. The comparison of the spectroscopic characteristics of ArI2(E,vE,nE) complexes obtained in this work and by Macarem and Loomis [Chem. Phys. Lett. 826, 140642 (2023)], has been carried out. Measurements of true luminescence spectra, corrected for the spectral dependence of the registration system sensitivity, allow us to determine the branching coefficients of the population of the vibrational and electronic predissociation products and even their vibrational distributions. In addition, this method allows us to determine the branching ratios of the ArI2(E,vE,nbE,nsE) populations and lifetimes of the complex if its vibrational predissociation is impossible.
Outcomes of modified arthrocentesis using concentric needle and cannula technique with sequential viscosupplementation and orthobiologics in both TMJ compartments
A low-cost four-component relativistic coupled cluster linear response theory based on perturbation sensitive natural spinors
We present an efficient implementation of four-component linear response coupled cluster singles and doubles (4c-LRCCSD) theory that enables accurate and computationally efficient calculation of polarizabilities for systems containing heavy elements. We have observed that the frozen natural spinor (FNS)-based truncation scheme is not suitable for linear response properties, as it leads to larger errors in static and dynamic polarizability values. In this work, we have introduced a “perturbation-sensitive” density to construct the natural spinor basis, termed FNS++. Using FNS++, we achieve excellent accuracy when compared to experimental data and other theoretical results, even after truncating nearly 70% of the total virtual spinors. We also present pilot applications of the 4c-LRCCSD method to calculate the polarizability spectra of 3d transition metals. By employing the FNS++-based 4c-LRCCSD, we have been able to compute polarizabilities for systems with over 1200 virtual spinors, maintaining low computational cost and excellent accuracy.
The unfolded protein response influences therapy outcome and disease progression in chronic lymphocytic leukaemia
Abstract Since genomics, epigenomics and transcriptomics have provided only a partial explanation of chronic lymphocytic leukaemia (CLL) heterogeneity, and since concordance between mRNA and protein expression is incomplete, we related the CLL proteome to clinical outcome. CLL samples from patients who received fludarabine-containing chemoimmunotherapy were analysed by mass spectrometry (SWATH-MS). One dataset compared pre-treatment samples associated with an optimal versus suboptimal response, while another compared paired samples collected before treatment and at disease progression. eIF2 signalling (pivotal to the unfolded protein response (UPR)), was identified as the most enriched pathway in both datasets (respective z-scores: − 6.245 and 3.317; p < 0.0001), as well as in a fludarabine-resistant CLL cell line established from HG3 cells (z-score: − 2.121; p < 0.0001). Western blotting revealed that fludarabine-resistant HG3 cells expressed higher levels of PERK, which phosphorylates the regulatory eIF2α subunit, and lower levels of BiP, an HSP70 molecular chaperone that inactivates PERK but preferentially binds to misfolded proteins during ER stress. The PERK inhibitor, GSK2606414, sensitised resistant, but not sensitive, HG-3 cells to fludarabine without affecting background cell viability or cytotoxicity induced by the BCL-2 inhibitor venetoclax. These findings identify the UPR as a novel determinant of therapy outcome and disease progression in CLL.
Revealing pre-catalytic CO2 recognition in styrene oxide complexes via rotational spectroscopy
High-resolution rotational spectroscopy combined with quantum chemical calculations was employed to investigate the non-covalent interactions between styrene oxide and carbon dioxide. Four low-energy complex isomers were predicted, among which the global minimum was experimentally identified through agreement between theoretical and measured rotational constants. The phenyl substituent was found to introduce additional non-covalent interactions beyond the typical CCO2⋯O tetrel bond, including secondary C⋯OCO2 tetrel bond and C–H⋯OCO2 weak hydrogen bond, which collectively stabilized the complex and distorted the epoxide ring. Further π-electron localization and natural orbital for chemical valence analyses revealed that the phenyl ring modulated local electron density, while comparative calculations of binding energy further indicate that the synergistic weak interactions between styrene oxide and CO2 contribute to enhancing the structural stability of the styrene oxide–CO2 complex. These results shed light on substituent-controlled CO2 recognition in epoxide frameworks, offering molecular-level insight that may inform the design of functional materials for CO2 capture and chemical transformation.
Application of lean management in medical laboratories to help treat patients with acute stroke
Anharmonic infrared spectra of cationic pyrene and superhydrogenated derivatives
Studying the anharmonicity in the infrared (IR) spectra of polycyclic aromatic hydrocarbons (PAHs) at elevated temperatures is important to understand the vibrational features and chemical properties of interstellar dust, especially in the James Webb Space Telescope (JWST) era. We take pyrene as an example PAH and investigate how different degrees of superhydrogenation affect the applicability of the harmonic approximation and the role of temperature in the IR spectra of PAHs. This is achieved by comparing the theoretical IR spectra generated by classical molecular dynamics (MD) simulations and the experimental IR spectra obtained via gas-phase action spectroscopy, which utilizes the infrared multiple photon dissociation. All simulations are accelerated by a machine learning interatomic potential, in order to reach first-principles accuracies while keeping computational costs low. We have found that the harmonic approximation with empirical scaling factors is able to reproduce experimental band profile of pristine and partially superhydrogenated pyrene cations. However, a MD-based anharmonic treatment is mandatory in the case of fully superhydrogenated pyrene cation for matching theory and experiment. In addition, band shifts and broadenings as the temperature increases are investigated in detail. These findings may aid in the interpretation of JWST observations on the variations in band positions and widths of interstellar dust.
The Drosophila DEG/ENaC PPK12 is a Na+ leak channel with a low Na+ affinity
Abstract DEG/ENaC ion channels have various functions in different organisms. In Drosophila, DEG/ENaCs are named Pickpockets (PPKs) and form a large insect-specific radiation with seven subfamilies containing 31 members. Several different functions have been proposed for PPKs, including salt and water taste. However, despite their many functions, most PPKs have not been functionally characterized in heterologous expression systems, leaving their functional properties unknown. Here, we expressed six PPKs in Xenopus oocytes, which are expressed in the chemosensory system of Drosophila larvae. We found that PPK12 forms a constitutively open ion channel that is permeable to Na+ ions. PPK12 currents do not saturate even at high Na+ concentrations, suggesting that PPK12 may be involved in sensing high salt concentrations. Our study shows that at least some PPKs are amenable to functional characterization in Xenopus oocytes, allowing to elucidate the relation of their functional properties with their proposed functions in the organism.
On-surface visualization of the influence of the chemical environment on halogen–hydrogen bonds at submolecular scale
The halogen–hydrogen bond has demonstrated remarkable potential in controlling molecular assembly and precisely steering reaction pathways on surfaces. However, few attempts have been devoted to explore the fundamental characteristics of halogen–hydrogen bonds in real space. Herein, we systematically investigate the influence of the local chemical environment of hydrogen atoms on halogen–hydrogen bonds. Combining high-resolution scanning tunneling microscopy investigations with density functional theory calculations, we clarify that tuning the chemical environment of hydrogen atoms varies corresponding halogen–hydrogen bonding strengths on the Ag(111) surface, leading to the formation of different two-dimensional tessellation patterns. Our studies provide real space insights into the mechanism of halogen–hydrogen bonds and establish a strategy for designing complex low-dimensional nanostructures on metal surfaces.
Exosome-like nanovesicles from Peucedanum Japonicum directly regulate inflammatory cytokines via small RNAs
Condensation vs cavitation in water: A simulation study
Condensation and cavitation in water play a crucial role in industry and atmospheric science. We employ molecular dynamics to investigate and compare both nucleation phenomena at 450 and 550 K, taking cavitation data mostly from our recent study [Lamas et al., J. Chem. Phys. 158, 124504 (2023)]. We obtain interfacial free energies across a wide range of supersaturation through direct coexistence, seeding, and, using a novel approach, also through spontaneous nucleation simulations. The consistency between these methods supports the validity of Classical Nucleation Theory even for nuclei as small as two molecular diameters in radius. Condensation at 550 K occurs several orders of magnitude faster than at 450 K due to the lower interfacial free energy. Unlike Lennard-Jones systems [Sanchez-Burgos et al., Phys. Rev. E 102, 062609 (2020)], cavitation and condensation are not governed by the same interfacial free energy trend. For condensation, interfacial free energy is nearly constant at 550 K and increases slightly at 450 K with nucleus size. For cavitation, in contrast, it decreases at both temperatures, leading to a higher cavitation rate. The kinetic pre-factor, influenced by the parent-phase density, further enhances the cavitation nucleation rate. Finally, the orientational ordering of interfacial molecules weakens with temperature and curvature, but no clear link between molecular structure and interfacial free energy is found. Our findings provide a comprehensive perspective on the thermodynamic and molecular factors governing nucleation in water, bridging the mechanisms of condensation and cavitation across different temperatures.
Cryptobenthic crab assemblages are more distinct across a 90 m depth gradient than 2500 km of shallow marine habitat in the Hawaiian archipelago
Approximations of the Iterative Stockholder Analysis scheme using exponential basis functions
In this work, we introduce several approximations of the Iterative Stockholder Analysis (ISA) method based on exponential basis functions. These approximations are categorized into linear and non-linear models, referred to as LISA and NLIS, respectively. By particular choices of hyperparameters in the NLIS model, both LISA and the Minimal-Basis Iterative Stockholder (MBIS) method can be reproduced. Four LISA variants are constructed using systematically generated exponential basis functions derived from the NLIS model applied to atomic systems. The performance of these LISA variants and NLIS models is benchmarked on 15 small molecules, including neutral, anionic, and cationic species. To facilitate comparison, we propose several metrics designed to highlight differences between the methods. Our results demonstrate that LISA, employing Gaussian basis functions derived from the NLIS model on isolated atomic systems, achieves an optimal balance of computational accuracy, robustness, and efficiency, particularly in minimizing the objective function.
The value of prealbumin in predicting post hepatectomy liver failure for patients with hepatocellular carcinoma undergoing major hepatectomy
Stockmayer fluid simulations for viscosity and glass transition temperature of ionic liquids
We develop a Stockmayer fluid model for molecular dynamics simulations of ionic liquids that captures molecular polarization, ionic conductivity, viscosity, and glass transition temperature, using ethylammonium nitrate (EAN) as an example. The ions in EAN are treated as spheres interacting via the Lennard-Jones potential with an embedded point charge and a permanent dipole moment. We show that our simulation results for EAN are consistent with experimental data and then explore the effects of the molecular parameters on the viscosity of ionic liquids. Our results indicate that viscosity monotonically increases with ionic charge and dipole moment but non-monotonically changes with ionic diameter (or molar volume). This non-monotonic trend arises from the competition among the electrostatic interactions, molecular packing, and size asymmetry between the cation and anion. Our model also shows that long-lived ion pairs result in higher viscosities.
Effect of gestational exposure to dim light at night on the behavior of rat dams and offspring
Spin-generator coordinate method for electronic structure
We present a new application of the generator coordinate method (GCM) as an electronic structure method for strong electron correlation in molecular systems. We identify spin fluctuations as an important generator coordinate responsible for strong static electron correlation that is associated with bond-breaking processes. Spin-constrained unrestricted HF (c-UHF) states are used to define a manifold of basis states for the Hill–Wheeler equations, which are discretized and solved as a non-orthogonal configuration interaction expansion. The method was tested on two-electron systems that are dominated by static and/or dynamic correlations. In a minimal basis set for H2, the resulting GCM quickly captures the ground-state full configuration interaction energy with just a few c-UHF states, whereas second-order perturbation theory on top of the GCM is needed to recover over 90% of the correlation energy in the cc-pVDZ basis set.
Pollutant dispersion and nanoparticle dynamics in magnetized bioconvection for sustainable water treatment
Abstract Water pollution has rapidly developed with industrialization and urbanization, making it difficult to sustain water treatment. Traditional methods are ineffective in removing nanoscale contaminants such as heavy metals and microplastics. The present work proposes a new MHD bioconvective hybrid nanofluid system with gyrotactic microorganisms acting under a permanent magnetic field to improve pollutant distribution and extraction. A mathematical model is formulated by integrating continuity, momentum, energy, nanoparticle concentration, microbial motility, and reaction-diffusion equations. The ordinary differential equations (ODEs) are obtained from the model by means of similarity transformations. Numerical solutions show that combining bioconvection with magnetic control greatly improves pollutant removal efficiency. Thermophoresis and Brownian motion help move nanoparticles. Increasing the Hartmann number slows fluid velocity due to Lorentz forces. At the same time, a higher bioconvection Péclet number encourages an even distribution of bacteria, which helps with pollutant spread. Validation against existing literature confirms the model’s correctness. This method provides a sustainable and energy-efficient way to purify water, using microbial dynamics and magnetic control for environmental cleanup.
String-like collective motion mediates the martensitic <i>α</i>–<i>β</i> transition in titanium
Recent computational studies have examined the structural relaxation time τα of cooled liquids, the atomic diffusivity D within grain boundaries of crystalline materials, and the interfacial regions of bulk, thin film, and nanoparticles of crystalline materials under equilibrium conditions. They have revealed the general occurrence of string-like collective atomic motion and its importance for understanding the typically non-Arrhenius dynamics of all these materials. In the present work, we extend our study of this type of collective motion in crystalline metal materials to consider the α–β displacive structural transition of titanium from its lower temperature hexagonal close-packed to body-centered cubic structure as the temperature (T) is elevated. In particular, we employ molecular dynamics simulation and focus on the role of string-like collective motion in mediating this displacive transition and the dynamics of the phase transformation process. Above the α–β transition temperature, as the temperature increases, we observe that the scale of collective motion progressively decreases, and the activation free energy of the moving interface of the new phase is well-described by the average string length Ls, similarly to τα of glass-forming liquids. As a special feature of this transition, we find that the strings are localized in channels having a temperature-dependent width within the crystal. We thus find another physical example of a class of materials in which collective motion plays a crucial role in material dynamics.