This study used the constant statistical tensor (CST) method to calculate mixing ratios (δ) for high-spin excited states in 182 Pt nuclide in the following heavy ion reactions: 170 Yb ( 16 O,4n) 182 Pt, 162 Dy ( 24 Mg,4n) 182 Pt and 163 Dy ( 24 Mg,5n) 182 Pt. To determine the multipole mixing ratios (δ) for all γ-transitions in the 182 Pt nuclide, the statistical tensor ρ2 (J i ) must be calculated for pure transitions or transitions considered to be pure. These ρ2 (J i ) values are considered constant for all levels with the same (Ji), and can thus be used to calculate the multipole mixing ratios of γ-transitions for both pure and mixed transitions. The obtained multipole mixing ratios show that most values calculated for pure transitions are very small, confirming that these transitions represent the pure electrical transition (E1) or (E2). However, the multipole mixing ratios calculated for the mixed transition were not the same as those obtained experimentally. Although the angular distributions for some γ-transitions had previously been experimentally obtained, their δ-values had not been previously calculated for all γ-transitions. The δ-values of these γ-transitions have been calculated in this work. The results for the mixing ratios values for γ-transitions in this study confirm the possibility of using the CST method as a tool for the calculation of the δ-values when it cannot be obtained experimentally.

Clear civil twilights often exhibit a range of pastel purples, but the combined angular and temporal distributions of this purple light are unknown. Such distributions can now be measured by using a hyperspectral camera fitted with a fisheye lens, which gives new insights into the spread and evolution of purple-light spectra and colors during ordinary (i.e., nonvolcanic) clear twilights. Because the purple light lacks clear-cut borders, a first step is to develop a perceptually based definition of its angular extent. Surprisingly, this leads to the discovery that colorimetrically distinct purples (1) sometimes appear in both the solar and antisolar skies and (2) change in markedly different ways with sun elevation.

Nearly a decade ago, it was discovered that the spherical cell body of the alga can act as a lens to concentrate incoming light onto the cell's membrane-bound photoreceptor and thereby affect phototaxis. Since many nearly transparent cells in marine environments have complex, often nonaxisymmetric shapes, this observation raises fundamental, yet little-explored questions in biological optics about light refraction by the bodies of microorganisms. There are two distinct contexts for such questions: the problem for light, typified by photosynthetic activity taking place in the chloroplasts of green algae, and the problem for light, where the paradigm is bioluminescence emitted from scintillons within dinoflagellates. Here we examine both of these aspects of “algal optics” in the special case where the absorption or emission is localized in structures that are small relative to the overall organism size, taking into account both refraction and reflections at the cell-water boundary. Analytical and numerical results are developed for the distribution of light intensities inside and outside the body, and we establish certain duality relationships that connect the incoming and outgoing problems. For strongly nonspherical shapes, we find lensing effects that may have implications for photosynthetic activity and for the angular distribution of light emitted during bioluminescent flashes.

In-beam angular distribution and linear polarization measurements with GRETINA using a simple energy-ordering approach

BackgroundBoron neutron capture therapy (BNCT) enables selective tumor irradiation by exploiting the high‐linear energy transfer particles generated from neutron interactions with 10B atoms. BNCT has been approved as an insurance‐covered medical treatment for recurrent head and neck cancer in Japan. Unlike photon radiotherapy, neutrons that come out of the collimator have an angular distribution. Therefore, it is necessary to keep the distance between the collimator and the patient as short as possible. However, for head and neck cancer treatments, patient anatomy often limits proximity to the collimator, creating an unwanted air gap. This ultimately increases the neutron exposure to surrounding healthy tissue.PurposeTo develop a freely deformable LiF‐polyethylene neutron shield and assess its impact on neutron/gamma attenuation and clinical organ at‐risk sparing in head and neck BNCT.MethodsA freely deformable neutron shielding device was constructed using polyethylene beads loaded with lithium fluoride encapsulated in a vacuum‐sealed cushion. Neutron and gamma‐ray attenuation were measured in a water phantom under clinical conditions using an accelerator‐based BNCT system (NeuCure®, Kansai BNCT Medical Center). Measurements were compared with a solid LiF‐polyethylene block and validated through Monte Carlo–based simulations in a commercial treatment planning system. Three representative head and neck cases were further simulated to assess clinical dosimetric effects.ResultsThe deformable shielding device reduced the thermal neutron flux by approximately 50%, compared with 60% for the solid LiF‐polyethylene block. Simulated head and neck treatments demonstrated significant OAR dose reductions (up to 46.6% in pharyngeal mucosa D50%) without compromising tumor dose coverage (D80% ≥ 20 Gy‐eq). Treatment delivery times were minimally affected (< 2 min difference) across all plans. A 5 mm positional perturbation analysis showed ≤ 0.5 Gy‐eq variation in GTV Dmin and pharyngeal mucosa D50 and Dmax.ConclusionsThe freely deformable LiF‐based neutron shielding device effectively attenuated stray neutron dose while maintaining target coverage in BNCT. Its adaptability and reusability make it a practical adjunct for patient‐specific dose optimization in clinical BNCT applications.

A bstract Some of the simplest models for the origin of neutrino mass involve right-handed neutrinos (RHNs), which could be either Dirac or Majorana particles — a distinction that has profound implications for lepton number conservation and the fundamental nature of neutrinos. We investigate the potential of the FASER experiment to distinguish between these two possibilities using signatures predicted by the Standard Model Neutrino Effective Field Theory (SMNEFT), where RHNs interact with Standard Model particles through higher-dimensional operators. We focus on RHNs produced via B , D , K , and π meson decays at the Large Hadron Collider and their subsequent three-body decays within the FASER detector. The kinematic and angular distributions of the decay products in the RHN rest frame differ significantly for Dirac and Majorana RHNs, and these differences manifest as distinct spatial distributions of electron-positron pairs at FASER. Using Monte Carlo simulations and a statistical analysis, we demonstrate that these spatial observables provide a robust experimental probe for determining the Dirac or Majorana nature of RHNs. For select production and decay operator combinations and RHN masses around 0.1 GeV, FASER can achieve discrimination at the 3 σ level.

ABSTRACT Single‐photon emitters radiate as electric dipoles, which limits light collection efficiency and complicates integration into flat photonic devices. Developing nanophotonic structures capable of directing photon emission with tunable angular distributions in the visible spectrum has been pursued for applications ranging from integrated optical systems to discrimination of molecular species. To date, such directional control has been achieved using components whose overall footprint is larger than the emission wavelength and often rely on lossy plasmonic components. Here, we employ the DNA origami technique for deterministic nanoscale assembly, positioning single fluorophores in nanometric proximity to a single silicon spherical nanoparticle (SiNP) and demonstrate unidirectional emission with forward‐to‐backward intensity ratios up to ∼7 dB. Furthermore, we show that a single silicon nanosphere antenna can function as a color router or a beam steerer depending on its size, emitter spectral range and emitter‐nanoparticle distance, enabling the use of these structures as versatile functional components in photonic devices.

Electric fields can modify protein-protein interactions and thereby influence phase behavior. In lysozyme–sodium thiocyanate solutions, we recently observed shifts in both the crystallization boundary and the liquid-liquid phase separation line under a weak applied field, along with a range of distinct crystal morphologies. Here, we explore how forming protein crystals respond to variations in field frequency and amplitude, focusing on the morphologies of complex, multiarm structures. At constant protein and salt concentrations, the applied field governs both the number and the angular distribution of crystal arms. These features are analyzed through Fourier analysis of microscopy images, revealing cooperative angular ordering among the arms. Based on these observations, we classify three principal multiarm protein crystal (pX) morphologies: flowerlike pX (dominant at high field strengths), triconic pX (appearing nonmonotonically at lower fields), and conic pX (widely observed under low-field conditions). Near the crystallization boundary, field-driven metastable structures such as tubules, clusters, nematic domains, and fibers also occur in response to the field. These findings demonstrate that electric fields effectively steer protein crystallization pathways and provide insight into the mechanisms of various multiarm crystallization.

In this paper, composite structures were fabricated by incorporating silver nanowires (AgNWs) with various metal oxides via the sol-gel method. This approach enhanced the electrical performance of AgNW-based transparent electrodes while simultaneously improving their stability under damp heat conditions and modifying the local medium environment surrounding the AgNW meshes. The randomly distributed AgNW meshes fabricated via drop-coating were treated with plasma to remove surface organic residues and reduce the inter-nanowire contact resistance. Subsequently, a zinc oxide (ZnO) coating was applied to further decrease the sheet resistance (Rsheet) value. The pristine AgNW mesh exhibits an Rsheet of 17.4 ohm/sq and an optical transmittance of 93.06% at a wavelength of 550 nm. After treatment, the composite structure achieves a reduced Rsheet of 8.7 ohm/sq while maintaining a high optical transmittance of 92.20%. The use of AgNW meshes as window electrodes enhances electron injection efficiency and facilitates the coupling mechanism between localized surface plasmon resonances and excitons. Compared with conventional ITO transparent electrodes, the incorporation of the AgNW mesh leads to a 17-fold enhancement in ZnO emission intensity under identical injection current conditions. Moreover, the unique scattering characteristics of the AgNW and metal oxide composite structure effectively reduce photon reflection at the device interface, thereby broadening the angular distribution of emitted light in electroluminescent devices.

The quality of three-dimensional macromolecular image reconstruction by cryo electron microscopy (cryo-EM) strongly depends on the number and the quality of the respective two-dimensional projections and on their angular distribution in space. Distributions with one or a few strongly preferred particle orientations may result in maps that are deformed in certain directions. A simple removal of overrepresented views may improve the quality of the reconstructed maps when the level of noise in the two-dimensional (2D) projections is low and the data-set size can afford this removal, but is counterproductive otherwise. Complementarily, giving an increased weight to underrepresented views, or taking multiple copies of them during the reconstruction, may improve the results, naturally, depending on how non-uniform the view distribution is. This work describes the results of three-dimensional (3D) reconstructions using an explicit correction of the number of overrepresented and underrepresented projections for non-uniformly distributed sets. Such correction can be considered as a potential preprocessing, fast and simple, during 3D reconstruction in the image-processing and cryo-EM structure-determination workflow.

The ultraviolet (UV) photodissociation dynamics of 2-methyl-1-propenyl radicals are investigated using the high-n Rydberg atom time-of-flight (HRTOF) technique in the 226-248 nm photolysis region. The radicals are generated from 193 nm photolysis of two precursors, 1-chloro-2-methylpropene and 1-bromo-2-methylpropene. The H-atom photofragment yield (PFY) spectrum of 2-methyl-1-propenyl in the 226-248 nm region exhibits a broad absorption feature peaking around 240 nm and an increased intensity at shorter wavelengths <228 nm, which quantum chemistry calculations attribute primarily to the 3s Rydberg state and/or the π* state. The product translational energy distributions, P(ET)'s, of the H-atom loss channels are modest, peaking at ∼7 kcal mol-1, with the average fraction of translational energy release 〈fT〉 remaining constant at 0.13-0.15 across the studied wavelength range. The angular distribution of the H-atom photofragments is isotropic and indicates a dissociation timescale longer than the rotational period of the radical. The photodissociation mechanism of 2-methyl-1-propenyl is found to be consistent with statistical unimolecular decomposition of the radical in a highly vibrationally excited ground electronic state to the methylenecyclopropane + H products, following internal conversion from the excited electronic states.

Abstract Within the framework of nonrelativistic QCD (NRQCD) factorization, we investigate the relativistic corrections to the production of a pair of $B_c$ family mesons in $e^+e^-$ annihilation. The study covers center-of-mass energies from the production threshold up to $2m_Z$, considering both the photon and $Z^0$-boson propagated processes. We find that the relativistic corrections are significant, with the corresponding $K$ factors of approximately 0.6. The azimuthal asymmetry, angular distribution, and transverse momentum distribution are also presented. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

The density of supercooled aqueous solutions of lithium, sodium, and potassium chloride was experimentally determined at atmospheric pressure down to -60 °C using dilatometry. To avoid freezing of the solutions, they were dispersed in a hydrophobic matrix, forming an emulsion, which inhibits heterogeneous nucleation. The experiments were conducted for solutions with concentrations up to the solubility limit under ambient conditions (NaCl and KCl) or up to the eutectic (LiCl). The temperature of maximum density and the apparent molar volume were calculated from density data. Molecular dynamics simulations were carried out for these systems within the same temperature and concentration ranges, using the TIP4P/2005 and Madrid-2019 force fields. Simulation and experimental results are critically compared, evaluating the performance of the model to reproduce the experimental results. Good agreement is obtained, a fact that avails the use of the model to study the structure of these solutions. This is performed by analyzing a set of radial distribution functions and the angular distributions of water molecules with respect to ions. The structural comparison among the cations indicates that Na+ and K+ salts share similar solvation patterns, while Li+ shows a distinct configuration, characterized by a tetragonal arrangement of water molecules around the ion that resembles that observed in solid-state environments. This finding aligns with the experimental results, since the analyses of the temperature of maximum density and apparent molar volume reveal that LiCl deviates from the tendencies observed for NaCl and KCl.

Vortex γ photons carrying orbital angular momenta (OAM) hold great potential for various applications. However, their generation remains a great challenge. Here, we successfully generate sub-MeV vortex γ photons via all-optical inverse Compton scattering of relativistic electrons colliding with a subrelativistic Laguerre-Gaussian laser. In principle, directly measuring the OAM of γ photons is challenging due to their incoherence and extremely short wavelength. Therein, we put forward a novel method to determine the OAM properties by revealing the quantum opening angle of vortex γ photons, since vortex particles exhibit not only a spiral phase but also transverse momentum according to the quantum electrodynamics theory. Thus, γ photons carrying OAM manifest a much larger angular distribution than those without OAM, which has been clearly observed in our experiments. This angular expansion is considered as an overall effect lying beyond classical theory. Our method provides the first experimental evidence for detecting vortex γ photons and opens a new perspective for investigating OAM-induced quantum phenomena in broad fields.

The dynamics of polar and nonpolar molecules colliding with an aqueous surface are characterized by scattering molecular beams of deuterated methane and ammonia, CD4 and ND3 (Ei = 28.9 and 30.3 kJ mol-1, respectively), from a flat liquid jet of cold salty water (8m LiBr, 230K). Translational energy distributions of scattered species collected as a function of collision geometry probe both impulsive scattering (IS) and thermal desorption (TD) mechanisms. We find that CD4 scattering is dominated by IS and exhibits a super-specular angular distribution. The fraction of TD scattering events is notably smaller for cold salty water than for dodecane, consistent with a higher free energy of solvation for CD4 in the water jet. In contrast, no scattering signal is seen for ND3 from the water jet, a result attributed to the high solubility and efficient protonation of ND3 in liquid water. The IS channel for CD4 was analyzed using a soft-sphere model, yielding a higher internal energy (Eint) and lower effective surface mass (meff) than was seen for Ne/water; the higher value of Eint is attributed to rotational excitation of the scattered CD4. These findings demonstrate that the outcomes of a gas-liquid collision-scattering trajectory, surface adherence, and energy transfer-are directed at the molecular level by both the gaseous scatterer and liquid surface.

The hydrophobic effect is a crucial guiding force in biological processes such as protein folding, molecular recognition, and structural stability. The enthalpy-entropy interplay at the hydration shell offers key insights into these phenomena. Although molecular dynamics simulations estimate enthalpy, determining entropic contributions, especially at the single-particle level, remains a challenge. This study calculates the translational (trans) and rotational (rot) entropies of water molecules around amino acids and compares the results with those of existing theoretical studies. By applying a permutation reduction technique to the water molecules in molecular dynamics trajectories and using the quasiharmonic approach, we computed the translational entropy of individual molecules. The rotational entropy was calculated using the angular orientation distribution of individual permuted water molecules. The solvation entropy calculated from individual contributions in our method agrees well with that from thermal integration (TI) and grid inhomogeneous solvation theory (GIST). We analyzed the spatial distribution of water entropy around amino acid backbones and side chains, observing a consistent loss of entropy near backbone atoms across all amino acids. Charged residues were associated with greater reductions in the water entropy compared to uncharged ones. Interestingly, a higher reduction in translational water entropy is observed near positively charged amino acids, whereas negatively charged residues reduce the rotational entropy to a greater extent. In general, the total water entropy loss (trans + rot) exhibits an inverted parabolic dependence on the hydropathy index of the amino acids. This study lays the groundwork for calculating water entropy around full protein surfaces, thereby advancing our understanding of hydration-driven processes in biomolecular systems. It also provides a foundation for exploring entropic behavior in molecular recognition, including protein-drug interactions.

The carbon oxygen ratio (C/O) at the end of stellar helium burning is a crucial nuclear input to stellar evolution theory. Knowledge of the C/O ratio with sufficient accuracy has eluded measurement over the past five decades. It is determined by the rate of oxygen formation in the fusion of helium with 12C, denoted as 12C(α, γ)16O. Even though recent methods employing a time projection chamber can measure the time-reverse photo-dissociation reaction, the results still do not show unambiguous agreement with the predictions of quantum scattering theory. Here, we improve this method using a N2O gas target. This improvement allows us to eliminate the background caused by 12C photo-dissociation events, obtain complete angular distributions (0∘−180∘), and measure the cross sections over the 1− resonance in 16O at Ecm ~ 2.4 MeV. These measurements resolve the discrepancy that was previously observed between the measured E1−E2 mixing phase angle (ϕ12) of 12C(α, γ)16O and the predictions of quantum scattering theory. This newfound agreement demonstrates the viability of our method for conducting measurements at lower energies.

This study introduces directional coherence loss coefficients (DCLCs) to quantify the angular distribution of sound field coherence loss, which arise from localized scattering distributions within an enclosure, from a receiver's perspective. Sound fields in the room are sampled by a spherical receiver and decomposed into plane waves using spherical harmonics expansion, yielding directional impulse responses (IRs). The time-dependent coherence coefficients between directional IRs in furnished rooms and their empty counterparts are analyzed for each direction. DCLCs are derived from these coherence coefficients and decide the transition between the coherent component-mainly representing specular reflections-and the incoherent component, accounting for scattering contributions from interior elements. This research extracts DCLCs from rooms with varying transducer positions founded on wave-based simulations and measurements from rooms with different element distributions. A hybrid model is proposed to reconstruct the sound field in a room with a single diffusive wall, where the coherent component is computed from the empty room case, and the incoherent component is simulated stochastically, with their relative weighting decided by DCLCs. Directional IRs from the hybrid model exhibit agreement with ground truth in terms of reverberation time, clarity, kurtosis, and spatial cross correlation coefficients, verifying the ability of DCLCs to characterize localized scattering distributions in enclosures.

A new muon spin rotation/relaxation/resonance (μSR) spectrometer is under design dedicated for the Chinese muon source, the Muon station for sciEnce technoLOgy and in DustrY (MELODY), which will be constructed at the China Spallation Neutron Source (CSNS) Phase II upgrade. The intrinsic asymmetry, detection rate and overall figure of merit (FoM) are key performance indices for the design of μSR spectrometers. The simulations are conducted via Geant4 toolkit, employing an idealized detector setup to analyze the kinetic energy and angular distribution of the decay positrons. The influences of various factors, including the muon beam profile, polarization, beam pipes, positron degraders, detector coverage angles and energy cuts, are systematically investigated. The simulation results are validated against theoretical expectations to ensure good accuracy. This work will provide good guidance for the placement of detector arrays and external magnets in the spectrometer construction phase.

The structural and dynamical properties of water confined in subnanometer, single-walled carbon nanotubes (CNTs) are investigated using molecular dynamics simulations. With radii ranging from 4 to 8 Å, we assess confinement-size effects using fully flexible CNTs with explicit carbon polarizability and the MB-pol water model. Density distributions reveal, that single-file water chains form in the narrow (10,0) CNT, pentagonal ring structures form in the intermediate (15,0) CNT, and a two-layer arrangement forms in the wider (20,0) CNT. Angular distributions show that the influence of carbon polarization on water orientation grows with CNT diameter, accompanied by a pronounced tilt of water molecules toward the CNT wall. Comparisons with the TIP4P/2005f model indicate that while this classical model captures structural trends, MB-pol affords a deeper description of interfacial water behavior by enabling direct simulations of infrared spectra from dipole trajectories and consistently accounting for polarization effects. Finally, simulations of vertically aligned CNT arrays demonstrate that intertube interactions significantly impact water dynamics: in stacked (20,0) configurations, intermittent hydrogen-bond lifetimes decrease by 20-25% and layer residence times drop by up to 20% relative to isolated CNTs. These findings illustrate the complex relationship between water structure and dynamics in relation to the size of the confinement and show that carbon polarizability and explicitly considering multiple CNTs are important factors to consider in modeling confined water.