Cross Section Research Articles

New insights into hair compartments swelling via atomic force microscopy and dynamic vapour sorption.

Preliminary investigations into the swelling of human hair upon absorbing moisture have been performed to better understand the roles of the various hair morphological subcompartments and their response to moisture. The isotherms of moisture sorption exhibited by hair were recorded via Dynamic Vapour Sorption (DVS) for separated cuticle and for cortex. Atomic Force Microscopy (AFM) imaging and nanoindentation were used to follow the changes in measured distances on the same areas of cuticle layers and cortex cells from a single fibre cross section, and to evaluate the change in these distances with changes in relative humidity. The data acquired by DVS moisture sorption and by AFM for the various morphological components of the hair fibre allowed for the evaluation of their swelling. The values were then used for estimating the cross-linking density of each morphological component. A relationship between the mechanics of the cortex and the cuticle of the fibre and their cross-linking density values was found to follow logarithmic-like dependencies. The size of the crosslink meshes at 90% RH was also evaluated and found to be of the length of the stretched disulfide bond. The analysis of hair swelling provides information on the crosslinks inside the fibre. The models used for calculating the crosslink density and the size of the meshes, as well as the relationship suggested graphically between the crosslinking density values and Young's Modulus, point to cystine as the decisive factor in the swelling process; the different amounts of cystine in each morphological component lead to different values of their crosslinking density and to their differing responses to mechanical stress.

Structures in the active Western Foothills of Southwestern Taiwan: Fault-related folding versus shale tectonics

Taiwan is an active orogen where a west-verging fold-and-thrust belt deforms a Plio-Pleistocene foreland basin sequence. In southwestern Taiwan, the 3–4 km thick Gutingkeng mudstone, Late Miocene to Early Pleistocene in age, has characteristics similar to mobile shales, such as overpressure conditions and sourcing mud volcanoes. Present uplift rates as fast as 2 cm/year are observed mainly on the footwall of steep thrusts, including the Gutingkeng Fault, which features several mud volcanoes. We integrate surface observations near this fault with regional subsurface data to construct an upper crustal cross section and evaluate the roles of the competing models of fault-related folding and shale tectonics in deforming the region. Field observations indicate steep and well-preserved bedding on the hanging wall and footwall and a wide reverse fault zone with penetrative shearing corresponding to the Gutingkeng Fault. No distinct structure explaining footwall uplift is found in the outcrops. At the cross-section scale, surface geology and subsurface data point to a structural style with fairly narrow anticlines with steep limbs growing above a relatively deep detachment. This geometry is not easily explained using classical fault-related fold models. We infer that folding on the Gutingkeng Fault footwall and in the core of a frontal anticline occurs through layer thickening (pure shear) facilitated by weak mudstone rheology. The increase in pore-fluid pressure under burial and tectonic compression within the fold cores can lead the mudstone to mobilize and undergo plastic flow, causing the inflation of the fold cores. Fold growth, possibly aided by shale tectonics, will have progressively increased the dip of the Gutingkeng thrust, eventually leading to thrust inactivity and uplift mainly occurring on the footwall. Our study area offers a unique opportunity to study an active shale-dominated fold-thrust belt exposed on-land and highlights the importance of combining geodetic observations to investigate ongoing deformations in these settings.

Reaction rates in quasiequilibrium states

Non-Maxwellian distributions are commonly observed across a wide range of systems and scales. While direct observations provide the strongest evidence for these distributions, they also manifest indirectly through their influence on processes and quantities that strongly depend on the energy distribution, such as reaction rates. In this paper, we investigate reaction rates in the general context of quasiequilibrium systems, which exhibit only local equilibrium. The hierarchical structure of these systems allows their statistical properties to be represented as a superposition of statistics, i.e., superstatistics. Focusing on the three universality classes of superstatistics—χ2, inverse-χ2, and log-normal—we examine how these nonequilibrium distributions influence reaction rates. We analyze, both analytically and numerically, reaction rates for processes involving tunneling phenomena, such as fusion, and identify conditions under which quasiequilibrium distributions outperform Maxwellian distributions in enhancing fusion reactivities. To provide a more detailed quantitative analysis, we further employ semiempirical cross sections to evaluate the effect of these nonequilibrium distributions on ionization and recombination rates in a plasma. Published by the American Physical Society 2025

Carbonization Tuned Core‐Shell Fe3O4@C Nanostructures with Enhanced Electromagnetic Wave Absorption

AbstractWith the advent of high‐power electronic devices, communication satellites, and military radar systems, electromagnetic (EM) waves have caused significant pollution. In this work, hollow Fe3O4@C (H‐FO@C) composites are synthesized by employing an in situ polymerization and carbonization treatment. Effects of carbonization temperature on electromagnetic wave absorption of core‐shell structured H‐FO@C composites are symmetrically analyzed, and the impedance matching and attenuation ability are improved significantly by controlling carbonization temperature. The reflection loss (RL) and effective absorption bandwidth (EAB) of H‐FO@C composites carbonized at 650 °C are improved to −51.85 dB and 5.36 GHz (thickness 2.1 mm), respectively. When the thickness of composites increases from 2.1 to 2.4 mm, the EAB reaches 6.24 GHz. According to CST Studio Suit, the radar cross section (RCS) reduction value can be 24.26 dB m2 for H‐FO@C composites. Both experiment and simulation results confirm that the H‐FO@C composites possess excellent EWA performance. This work provides a new way for advancing EWA materials.

Coherent photoproduction of J/ψ mesons in ultraperipheral Pb–Pb collisions at CMS

In this contribution, we briefly describe the CMS results on J/ψ photoproduction in Pb–Pb collisions, in which the coherent J/ψ photoproduction cross section as a function of the photon-nucleus center-of-mass energy (WγN^Pb) was measured up to 400 GeV. The cross section is observed to plateau above WγN^Pb ≈ 40 GeV and up to 400 GeV, accessing very small Bjorken-x values of ≈ 6 × 10⁻⁵.

Gluon Sivers function from forward exclusive χc1 photoproduction on unpolarized protons

Exclusive production of a χc1 axial vector quarkonia in photon-proton scattering at high energies requires a C-odd t-channel exchange. In the limit of vanishing momentum transfer this occurs either via the exchange of a photon, the Primakoff process, where the spin of the proton does not change. For axial-vector meson production, as a consequence of the Landau-Yang theorem, the Primakoff cross section is finite as t→0. Alternatively, a C-odd spin dependent Odderon can be exchanged, which involves a spin flip of the proton. The resulting cross section is related to the square of the collinear trigluon correlator or the k⊥-moment of the gluon Sivers function. Using two models for the gluon Sivers function from the literature we compute the ratio of Sivers to Primakoff cross sections and the angular coefficient λθ governing the angular distribution of the χc1→J/ψ+γ decay as functions of x. We point out that these observables constrain the magnitude of the gluon Sivers function at small x which could be accessed in electron-proton scattering and ultraperipheral proton-proton and nucleus-proton collisions. Published by the American Physical Society 2025

Inclusive and Diffractive Dijet Photoproduction in Ultraperipheral Pb-Pb Collisions at the LHC

In this contribution, we summarize NLO pQCD predictions for inclusive and diffractive dijet photoproduction in Pb-Pb UPCs at the LHC. We demonstrate that the theory describes well the preliminary ATLAS data on the inclusive cross section, which probes nuclear parton distributions (PDFs) down to x_A ~ 0.005 and which can reduce current uncertainties of the small-x nuclear gluon distribution by approximately a factor of 2. Employing predictions of the leading twist approach to nuclear shadowing for nuclear diffractive PDFs, we calculate the cross section of diffractive dijet photoproduction and show that its x_gamma} dependence is sensitive to the effect of nuclear shadowing and the mechanism of QCD factorization breaking in hard diffraction. We also find that due to large leading twist nuclear shadowing and restricted kinematics, the diffractive contribution to the inclusive cross section of dijet photoproduction does not exceed 5-10%, which helps with an ambiguous interpretation of the ATLAS data.

Light-by-light scattering in ultraperipheral collisions of heavy ions with future FoCal and ALICE 3 detectors

I present possible future studies of light-by-light scattering using FoCal@ALICE and ALICE 3 detectors. Different mechanisms are discussed. The PbPb → PbPb γγ cross section is calculated within the equivalent photon approximation in the impact parameter space. Several differential distributions are presented and discussed. We predict the cross section in the (mb-b) range for typical ALICE 3 cuts, a few orders of magnitude larger than for the current ATLAS or CMS experiments. We also consider the two-π⁰ background, which can, in principle, be eliminated in the new kinematical range for the ALICE 3 measurements by imposing dedicated cuts on diphoton transverse momentum and/or so-called vector asymmetry.

Measurement of dilepton production from photon fusion processes in Pb+Pb UPC with the ATLAS detector

Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons, leading to multiple photon-induced processes. This report presents a series of measurements of dilepton production from photon fusion performed by the ATLAS Collaboration. Recent measurements of exclusive dielectron production in ultra-peripheral collisions (UPC) are presented. These processes provide strong constraints on the nuclear photon flux and its dependence on the impact parameter and photon energy. Comparisons of the measured cross sections to QED predictions from the STARLight and SuperChic models are also presented. Tau-pair production measurements can constrain the tau lepton's anomalous magnetic dipole moment (g-2), and a recent ATLAS measurement using muonic decays of tau leptons in association with electrons and tracks provides one of the most stringent limits available to date. Furthermore, measurements of muon pairs produced via two-photon scattering processes in hadronic (i.e. non-UPC) Pb+Pb collisions are discussed. These non-UPC measurements provide a novel test of strong-field QED and may be a potentially sensitive electromagnetic probe of the quark-gluon plasma. These measurements include the dependence of the cross section and angular correlation on the mean transverse momenta of the dimuon pair, the rapidity separation between the muons, and the angle of the pair relative to the second-order event-plane, all measured differentially as a function of the Pb+Pb collision centrality.

Development of convergent adaptations reveal highly conserved early ontogenetic skull shape in fishes with amphibious vision

The development of skeletal elements in fish is strongly influenced by the functional demands and environmental constraints they face during different life stages but mostly occurs during their larval development. One example of late modifications within the skeletal system is the adaptation of the skull and eye morphology that allows for amphibious vision in the four-eyed fishes Anableps spp. Another species that is equally capable of simultaneous aquatic and aerial vision, Rhinomugil corsula, has been widely neglected in this field of research, although it presents great opportunities for comparative analyses on the evolution of this ability. We studied the development of the skull and eyes of Rhinomugil based on morphological, morphometric, and histological data. While cross sections reveal that the eyes develop required morphological adaptations for simultaneous amphibious vision in larval life stages, the restructuring of the neurocranium which causes the dorsolateral relocation of the eyes occurs only during late juvenile development. In Rhinomugil and Anableps, restructuring of the skull and eye occurs during similar developmental phases suggesting that the development of the skull shape is widely conserved and cannot easily be changed during larval development.

Degradation of PGM and PGM-free Coatings on PEMWE Porous Transport Layers.

A good and long-term stable electrical contact between the porous anode transport layer (PTL) and the adjacent catalyst layer is essential for efficient polymer electrolyte membrane water electrolyzers. This study describes the extensive comparison of seven titanium passivation-protecting coatings using short- and long-term measurements for at least 2000 h. The measurements are supported by before and after scanning electron microscope investigations of cross sections, energy-dispersive X-ray spectroscopy, X-ray diffractometry of the coatings, contact resistance measurements, and ex situ rapid aging tests. Overall, iridium and platinum PTL coatings offer outstanding contact and excellent corrosion protection. Compared to the uncoated reference sample, platinum shows a 93% reduction in the overall degradation rate to 7 μV h-1 (at a current density of 3 A cm-2) over 5000 h and even reduces ohmic overvoltages over time in the first 2000 h. Interestingly, the interface to the flow field does not appear to be influenced by precious metal coatings and, hence, does not need to be coated. In contrast, niobium and titanium nitride PTL coatings under investigation do not provide an improvement compared to the uncoated reference but show dissolution and oxidation phenomena, respectively. Titanium hydride produced by hydrochloric acid improves the electrical contact and reduces degradation by 49% overall and 62% in terms of ohmic overvoltages compared to the uncoated reference. It also shows a saturation behavior in degradation with a stable rate of 23 μV h-1 in the second 1000 h of the measurement. Ex situ rapid aging tests additionally support the main trends. For all surface treatments, more detailed information about the occurring aging mechanisms and reversible overvoltages is obtained by separating the degradation rate into partial rates of the overvoltage mechanisms.

Nipping analysis of rectangular leaf springs

Abstract Nipping analysis of graduated-length leaf springs with uniform rectangular cross section of all leaves is presented. Initial gaps between leaves of the pre-assembled spring are determined such that the maximum bending stresses in all the leaves of the assembled and externally loaded spring become equal to each other. The expressions are derived for leaf springs consisting of two-to-five graduated-length leaves, which are stiffened by an additional full-length leaf placed atop. The reduction of the maximum bending stress achieved by nipping is quantified in each case. The deformed shapes and the residual gaps between the leaves in the loaded spring configuration are determined and discussed.

Collision geometry in UPC dijet production

We present a comprehensive NLO pQCD study on inclusive dijet photoproduction in ultraperipheral nucleus-nucleus collisions (UPCs). Our analysis takes into account the finite size of both the photon-emitting and the target nucleus, estimated using the Wood-Saxon nuclear density profile. We show that a significant part of the measured dijets at large z_\gamma in UPC Pb+Pb collisions at 5.02 TeV come from events with relatively small impact parameters of the order of a few nuclear radii, and the cross section predictions thus become sensitive to the modelling of the collision geometry and photon flux near the source nucleus. In addition, we include the modelling of electromagnetic breakup survival factor needed for a direct comparison with the experimental data and study the resolution power of this process in terms of the impact-parameter dependent nuclear parton distribution functions.

Four-pion state in UPC

The production of four pion events in ultraperipheral heavy-ion collisions at RHIC and LHC energies is studied. Preliminary H1 data is used to enhance the understanding of the poorly known process. Predictions for photon-nucleus interactions are calculated for various excited states of mesons. Agreement between theoretical predictions and available STAR data at RHIC is presented. The comparison of the four-pion invariant mass spectrum and nuclear total cross section indicates that rho(1570) plays a crucial role in accurately describing existing experimental data. Nuclear predictions for LHC energy in the central region of rapidity are also provided.

Photoproduction of J/ψ and dileptons in Pb–Pb collisions with nuclear overlap

Photon-photon reactions and the production of J/ψ meson through photonuclear reactions have been extensively studied in ultra-peripheral heavy-ion collisions, in which the impact parameter is larger than twice the nuclear radius. In recent years, coherently photoproduced J/ψ and dilepton production via photon-photon interactions have also been observed in nucleus-nucleus (A–A) collisions with nuclear overlap. The former can help to constrain the nuclear gluon distributions at low Bjorken-x and high energy, while the latter could be used to further map the electromagnetic fields produced in heavy-ion collisions. In addition, these measurements can shed light on the theory behind photon-induced reactions in A–A collisions with nuclear overlap, including possible interactions of the measured probes with the formed and fast expanding quark-gluon plasma. Since the produced quarkonium is expected to keep the polarization of the incoming photon due to s-channel helicity conservation, the photoproduction origin of the J/ψ yield excess at very low transverse momentum, pT, can be confirmed by the measurement of the J/ψ polarization. The ALICE detector can perform quarkonium production measurements at both mid (|y|<0.9) and forward (2.5<y<4) rapidities down to pT = 0. In the following, the new ALICE measurements of the J/ψ y-differential cross section and the first polarization results of coherently photoproduced J/ψ via the dimuon decay channel at forward rapidity in Pb–Pb collisions at √sNN = 5.02 TeV are reported. Additionally, the measurement of an excess with respect to expectations from hadronic production in the dielectron yield, at low mass and pT, at midrapidity in Pb–Pb collisions at √sNN = 5.02 TeV, is presented. The results are compared with available theoretical models.

Simultaneous Improvement and Tailoring Upconversion and Downshift Luminescence of Cs2NaErCl6 via Yb3+ Alloying for Versatile Photoelectric Applications.

Lead-free double perovskite (DP) materials have garnered growing interest because of their outstanding optoelectronic attributes. Nevertheless, realizing efficient, multimodal photoluminescence (PL) with adjustable emission spectra within single-host DP materials still poses a formidable hurdle. Herein, Er-based lead-free DPs (Cs2NaErCl6) were developed, which achieves downshift (DS) emissions from visible to near-infrared (NIR) and multicolor upconversion (UC) emissions, resulting from the abundant energy levels of Er3+ ions. Alloying with Yb3+ introduces new Yb3+-Er3+ cross-relaxation (CR) pathways, leading to a 308.5-fold increase in DS red emission and achieving a maximum color purity of 98.63%. Additionally, Yb3+ alloying enhances UC luminescence by 10.8-fold due to its strong absorption cross section around 980 nm. The colors of the UC emission can be adjusted by altering the doping concentration of Yb3+ and laser power density. Spectral analysis and theoretical calculations reveal the high compatibility of Yb3+ ions with Cs2NaErCl6, and the critical role of CR and energy-transfer processes in achieving efficient, tunable, and multimodal PL. Furthermore, the developed DP materials have been utilized in anticounterfeiting, information encoding, and narrow-band NIR photodetectors, expanding the versatile uses of rare-earth (RE)-based DP materials in the optoelectronics field.

Remarks on Compton forward scattering singularity in the NCQED

We investigate the behaviour of head-to-head high energy Compton scattering in the θ-exact NCQED in the amid its unresolved forward scattering singularity. We model the effect of the currently unknown resolution to this unavoidable singularity by cut-offs which are functions of the control variable s/ΛNC2, and find that such cut-off functions can suppress NC contributions to the inverse Compton scattering to negligible. Discussed cut-offs leave the unpolarised integral cross section of the forward region larger than the backward region all the time, making the former potentially visible in the future linear collider experiments when the NC scale ΛNC≳1 TeV.

The correlation between muscle loss and the severity of vascular stenosis in elderly patients with peripheral artery disease: a retrospective analysis utilizing computed tomography

BackgroundPeripheral artery disease (PAD) is a globally prevalent atherosclerotic disease associated with an increased risk of cardiovascular and cerebrovascular diseases and a poor prognosis. Skeletal muscle loss (sarcopenia) is particularly common in patients with PAD and is closely associated with poor prognosis.AimsThe aim of this study was to evaluate the area, density and fat infiltration of skeletal muscle in patients with PAD by CT, and to analyze their relationship with the degree of vascular stenosis.MethodsA total of 233 PAD patients who underwent lower extremity CTA in Beijing Hospital were included in this study. Image segmentation was performed using Slice-O-Matic® software, and parameters such as skeletal muscle area, density, and fat infiltration were measured at L3, L4, mid-thigh, and maximum soft tissue cross section of the lower leg. At the same time, the degree of lower extremity arterial stenosis was evaluated by CTA. The lower extremity arterial stenosis severity was graded as 0 (0–30%), 1 (31–50%), 2 (51–70%), 3 (71–99%), or 4 (occlusion).Then the CTA-score was calculated by summing the stenosis scores of the abdominal aorta and the lower limb arteries.ResultsPatients were categorized into high (n = 113) and low (n = 120) CTA score groups. Among males, those in the low score group had higher muscle indices at L3, though not statistically significant. However, thigh and calf muscle areas were significantly larger in low score males (P < 0.001). High score patients had greater intermuscular fat indices. Regression analysis indicated that vascular stenosis accounted for 5% of the variance in muscle mass, with SFA, PoA, and PTA stenosis having the strongest correlations.DiscussionOur study reveals how vascular stenosis affects muscle mass and composition in PAD patients, with the SFA, PoA, and PTA having the greatest impact due to their key role in lower limb blood supply. Severe stenosis leads to muscle mass reduction and increased fat infiltration, possibly due to chronic inflammation and oxidative stress. These findings highlight the need to address muscle health in PAD management, as targeting muscle atrophy and fat infiltration could enhance patient outcomes.ConclusionsPAD severity had a significant effect on the muscles of the lower limbs, especially the stenosis of the SFA, PoA, and PTA. CT evaluation provides a new perspective for understanding muscle loss in patients with PAD.

A systematic study of initial state quark energy loss in fixed target proton nucleus collisions

In this article, we investigate parton energy loss in cold nuclear matter by studying the ratio of Drell–Yan production cross sections in fixed-target proton-nucleus (p + A) collisions. We analyze Drell–Yan production cross-section data from the Fermilab E866 and E906 experiments using two different quark energy loss parametrization models and various parton distribution functions for 800 and 120 GeV proton beams incident on light and heavy nuclear targets. The sensitivity of the energy loss parameter on the employed parton distribution function has been thoroughly investigated. Our results have been used to predict the target mass dependence of Drell–Yan production in upcoming proton-induced collisions at SPS and FAIR.

Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction with ALICE

Coherent vector meson photoproduction in ultraperipheral heavy-ion collisions is a well established tool to probe the gluon structure of the colliding nuclei. We will focus on the observation of quantum interference effects in the ρ 0 meson photoproduction, in the form of angular anisotropy. Such an anisotropy appears due to two different factors: first, the photons involved in the process are linearly polarized along the impact parameter, and, second, quantum interference occurs between the two amplitudes that contribute to the ρ0 photoproduction cross section. Furthermore, the interference effect strongly depends on the impact parameter of the collision, which acts as the distance between the openings of a two-slit interferometer. We present the first measurement of this anisotropy in coherent ρ0 photoproduction from ultraperipheral Pb–Pb collisions at a center-of-mass energy of √sNN = 5.02 TeV per nucleon pair, as a function of the impact parameter of the collision. The latter is estimated by classifying the events in nuclear-breakup classes defined by neutron emission. The ρ0 mesons are detected by the ALICE experiment through their decay into a pion pair. The anisotropy occurs as a function of ϕ, defined as the azimuth angle between the two vectors formed by the sum, and the difference, of the transverse-momentum of the pions, respectively. It results in a cos(2ϕ) modulation of the photoproduced ρ0; the amplitude of the modulation is found to increase by about one order of magnitude from large to small impact parameters. This trend is compatible with the available theoretical predictions