Browse Articles

Sodium and potassium analysis of individual coccoliths by secondary ion mass spectrometry

Abstract Coccoliths are individual plates of calcium carbonate that comprise the shells of marine calcifying haptophyte algae. Their remains provide an excellent sedimentary archive for the reconstruction of past environmental parameters. Using nano-scale secondary ion mass spectrometry (NanoSIMS), we measured the Mg, Sr, Na and K contents in individual coccoliths of Emiliania huxleyi , now named Gephyrocapsa huxleyi, to explore their potential as a paleoproxy. For recent environmental samples from the Mediterranean and Black Sea as well as cultured specimens, all elements appeared to be homogeneously distributed within, but highly variable among, the individual coccoliths. Mg/Ca and Sr/Ca ratios covered a range of 0 . 06–83 mmol mol −1 and 1 . 9–3 . 8 mmol mol −1 , respectively, and were in line with the previously determined values. Na/Ca ranged between 1 . 6–186 mmol mol −1 . K/Ca could not be calibrated, but the measured 39 K + / 44 Ca + ion count ratios varied between 0 . 03–2 . 7. Although the Na/Ca ratios significantly decreased with increasing total alkalinity and salinity in the Mediterranean samples, these trends were not observed in samples collected from cultures where the alkalinity and salinity varied separately. Similarly, K/Ca ratios showed no clear trends with total alkalinity or salinity of the culture medium. Calcification in coccolithophores is biologically controlled and this may mask the impact of environmental factors on the observed variation in the Na and K content of individual coccoliths of E.   huxleyi .

Subpicosecond thermalization of carriers in polar GaN/AlN quantum dots

We investigate at room temperature the thermalization and recombination dynamics of near-resonantly photogenerated carriers in c-plane GaN/AlN wurtzite quantum dots (QDs) using time-resolved photoluminescence and non-degenerate pump–probe differential transmission. Owing to a continuous gradient in dot height, the QD ensemble exhibits a broad emission range from 3.5 to 4.5 eV. Time-resolved photoluminescence reveals two distinct recombination lifetimes associated with two families of QDs with different morphologies, whose emission energies are governed by the interplay between the quantum-confined Stark effect and lateral confinement. Pump–probe measurements evidence an ultrafast carrier thermalization with subpicosecond rise times on the order of 200 fs, significantly shorter than in other epitaxial III–V QD systems. At longer delays, the relaxation dynamics is non-exponential and strongly dependent on both carrier density and probe energy. It is reproduced by a phenomenological model based on multi-carrier scattering processes, whose efficiency progressively vanishes as the probe energy approaches the luminescence maximum, where interband recombination dominates.

Effects of a maternal–infant telecare program on postpartum maternal confidence and sleep quality of mothers and infants

Abstract The change in the medical payment system has shortened postpartum hospitalization, limiting the time for nursing staff to provide care and education. In Taiwan, many postpartum women choose “doing the month” in postpartum nursing care centers with professional support. However, leaving these centers often increases maternal stress as they transition to independent caregiving, impacting their confidence and sleep quality. Additionally, difficulties in establishing infants’ sleep patterns further disrupt maternal sleep. To address these challenges, the maternal-infant telecare program was introduced to provide continued support after discharge. To explore the effectiveness of the maternal-infant telecare program on postpartum women’s confidence, sleep quality, and infants’ sleep quality. A cross-sectional research design was used in this study. Eighty-two postpartum women were recruited from a postpartum nursing care center in Northern Taiwan. Data were gathered at three separate time points (pretest, Posttest 1, Posttest 2). All statistical tests were performed using the SPSS 24 software. Data analyses included descriptive statistics, independent t-tests, and Generalized Estimating Equation. A total of eighty-two postpartum women were recruited through convenience sampling. The results of this study showed that after the intervention, postpartum confidence increased from an average of 43.99 to 51.72, postpartum sleep quality improved from 23.35 to 19.33, and the number of infants’ nighttime awakenings, as reported by postpartum women, reduced from an average of 2.77 to 1.12 at twelve weeks. The maternal-infant telecare program demonstrated potential benefits in enhancing postpartum women’s confidence, improving sleep quality, and reducing the frequency of infants’ nighttime awakenings. Therefore, the program merits further promotion and broader application in postpartum care.

The Sareh twist: A hidden geometric principle in origami tessellations

Origami techniques originate from the ancient paper-folding traditions of China and Japan. Since the mid-20th century, origami engineering has developed into an independent technology, transforming concepts of foldable and deployable structures in aerospace. More recently, new application areas have emerged, including the design of robots, biomedical devices, antennas, shock absorbers, and metamaterials. This study highlights a range of novel aspects of a twist that underlies both the folding of two-dimensional flat-foldable units and their periodic tilings, as well as three-dimensional structures, where it manifests as an internal, chiral movement enabling the transition between flat-folded and deployed configurations. The principle of twist was first explicitly identified by Pooya Sareh in crystallographic origami tessellations derived from the Miura-ori and is referred to here as the “Sareh twist.” Building on this concept, the present study extends the role of twist to four domains: degree-4 vertex units in single and docked tiles; conic transformations with the vertex as a pivot point; the twist-inducing diagonal fold in rectangles, which was crucial for defining industrial paper format ratios by Wilhelm Ostwald around 1911 and is adapted here to parallelograms; and finally, the internal twist of the cylindrical Kresling pattern developed by the author. The key innovation of this work is the development of a general approach that transforms even the most complex geometries into Sareh twist units defined by their specific symmetries. This approach not only advances the rational design of folded structures but also enhances our understanding of biological patterns.

An improved lightweight YOLOv11 algorithm for weld surface defect detection

Pulse formation and spectral broadening in continuous-wave optical parametric oscillator with dispersion control

We report the initiation of pulse formation and significant spectral broadening in a continuous-wave (cw)-pumped optical parametric oscillator (OPO) in a degenerate doubly resonant oscillator (DRO) cold cavity under group-delay dispersion (GDD) compensation. The analysis of temporal, phase, and spectral domains is performed using coupled-wave equations and the Split-Step Fourier method. With GDD compensation, in the steady state, the temporal output exhibits characteristics indicative of an incipient stage of pulse formation, while the spectral density shows an approximately sixfold increase compared to that of a conventional DRO. Furthermore, the influence of key OPO parameters such as input pump power, crystal length, cavity length detuning, pump phase fluctuations, temperature instability, and third-order dispersion on the temporal and spectral characteristics of the cw GDD-compensated DRO is studied, highlighting the robustness and stability of the system.

Analysis of the evolution and spatial effects of green space pattern in China’s urbanization process: a case study of Guangzhou City

Erratum: “Goldak’s double ellipsoidal thermal profile model of transition jitter and signal-to-noise ratio for heat assisted magnetic recording” [J. Appl. Phys. 138, 023902 (2025)]

A novel multi-module neural networks strategy of human emotion recognition in the human-robot interaction

Charge transport and positively charged defects in Ta2O5/SiO2 dielectric stacks

The electrical properties of Ta2O5/SiO2 stack structures are investigated, focusing on charge transport and the presence of positively charged defects. Capacitance–voltage (C–V) and triangular voltage sweep measurements revealed the existence of positively charged defects, which influence the electrical behavior of the stack. The origin of the defects is discussed with emphasis on the possible incorporation of alkali ions in Ta2O5. The current–electric field (J–E) characteristics were analyzed using hopping conduction, Poole–Frenkel emission, and Fowler–Nordheim (FN) tunneling models, demonstrating that hopping and FN tunneling adequately describe the experimental data at moderate and high electric fields, respectively. Fitting of the J–E data yielded physically reasonable parameters, including hopping distances of 1.1–1.5 nm, activation energies around 0.9 eV, and FN barrier heights of approximately 2 eV, consistent with known SiO2 and Ta2O5 interfaces. The results indicate that electron transport in these stacks is primarily controlled by the SiO2 layer and the SiO2/Ta2O5 interface, while the Ta2O5 layer contributes traps that facilitate field-assisted hopping. These findings provide insight into the interplay between trap states and tunneling mechanisms in high-k oxide stacks and are relevant for the optimization of dielectric stacks in electronic devices.

Explainable LSTM-AdamW based fault diagnosis of aircraft rotating components using airborne acoustic signals under dynamic operating conditions

Harnessing orbital angular momentum in solids from electrons to quasiparticles

Spintronics has advanced memory and logic technologies by utilizing the electron's spin degree of freedom. In contrast, the electron's orbital angular momentum (OAM) was long regarded as quenched in transition metals due to crystal field effects and considered relevant only through spin–orbit coupling. Recent theoretical and experimental developments have overturned this view by revealing that Bloch states can host momentum-dependent orbital textures, enabling the generation and long-range transport of orbital currents even in light transition metals. This progress has given rise to the emerging field of orbitronics, which explores OAM as an active and tunable degree of freedom for information transfer and magnetization control. This review summarizes the fundamental mechanisms underlying orbitronics, including OAM generation via the orbital Hall effect and the orbital Rashba–Edelstein effect, the propagation and detection of orbital currents, and their conversion into efficient orbital torques on ferromagnets. We further highlight key experimental advances demonstrating long-range orbital transport and discuss how light-element materials can serve as effective orbital sources. Extending beyond electrons, we also examine the emergence of OAM in quasiparticles such as magnons and phonons, where twisted modes and valley pseudo-angular momentum reveal the universality of OAM physics. Together, these developments establish orbitronics as a new framework in condensed matter research, offering promising routes toward energy-efficient memory, logic, and sensing technologies.

Fuzzy adaptive nonlinear MIMO control for rigid coupled multibody robots using reinforcement learning model

Chiral anomaly bulk states in acoustic S-graphene with multiple Dirac points

Dirac points (DPs) lie at the core of topological physics. Beyond robust in-gap edge states, chiral-anomaly bulk states (CABSs) induced by finite-size effects enable resilient bulk transport. Extending CABS research from systems with a single DP pair to those with multiple pairs introduces additional degrees of freedom and richer transport phenomena. Here, we investigate the CABSs in finite-size acoustic S-graphene systems containing two distinct pairs of DPs. We show that sample-size tuning yields CABSs with diverse dispersion slopes. Leveraging both dispersion types and symmetry properties of these CABSs enables precisely controlled directional bulk radiation with quantized branch multiplicities. These results expand the classification of CABS dispersion relations, demonstrate efficient bulk-wave manipulation, and help in designing compact, multichannel acoustic waveguides, and multivalley device architectures.

Soil nitrous oxide and methane emissions in contrasting land use of the West African Sudanian savanna

A point-particle-based hydride shell-shedding model for ejecta particle transport in reactive environments

A shock wave passing over a rough or perturbed metal surface will induce a limiting case of Richtmyer–Meshkov instability and will cause small particles to eject from the surface and transport into the surrounding medium. These particles are known as ejecta and can be either solid or liquid in nature. Recent experiments have shown that liquid cerium ejecta clouds exhibit unexpected non-monotonic acceleration behaviors as well as temperature plateaus after a brief temperature rise if they are transporting in a chemically reactive, hydrogen-based medium while they act as expected in an inert medium. This work details a point-particle model developed for reactive cerium ejecta transport, which attempts to account for these new physics through the behavior of a developing solid hydride shell, which is believed to form as a product of the reaction. The overall model incorporates the effects of the reaction on the particle properties as well as the effects of potential shedding of the shell into sub-micrometer scale flakes and potential phase change of the hydride if the ejecta particles reach the melt point of the hydride layer. The model is tested by performing simulations of the original motivating experiments and comparing quantities, such as ejected mass, velocimetry, and temperature profiles, against the experimental data. While the model is able to capture many general features of the observed anomalies, some inaccuracies still exist. These point to both missing physics in the model (such as a deuterium adsorption mechanism on the hydride layer) as well as a lack of knowledge of certain material properties (such as the strength of cerium hydride to determine dynamic fracture thicknesses) needed to fully reduce the uncertainties in the model by up to an order of magnitude and perform a true attempt at model validation.

Percolation threshold for vertical fluid flow through granular sea ice

Experimental and numerical investigations of ionic electrospray thruster beam in vacuum chamber

This paper presents a correlated experimental and simulation study of an ionic electrospray thruster beam. The effects of vacuum chamber on the thruster beam are inferred through comparisons of laboratory measurements and simulations of the beam in an idealized chamber environment. While laboratory and simulation results agree qualitatively, the quantitative comparison shows that, for single positive polarity beams, the experimental measurement exhibits a more focused, higher density beam core and a flatter potential profile in the radial direction than the beam in simulation. This difference is mostly due to the background plasma generated in the vacuum chamber. The background plasma provides partial neutralization of the ion beam, thus reducing the radial direction beam spreading due to the space charge effect. The background plasma also cuts off the beam expansion process, thus reducing the radial direction potential gradient. Thus, vacuum chamber measurements of electrospray thruster beams will over-predict the density in the beam core region but under-predict beam potential with respect to ambient for the in-space condition.

A xenotransplantation model for reactivation of paternal UBE3A using human-specific antisense oligonucleotides

Abstract For many neurodevelopmental disorders, genetic treatment discovery is complicated by non-homology between human and non-human model system genomes. Antisense oligonucleotides (ASOs) influence protein expression by sequence-specific binding of RNA, resulting in targeted degradation or alternative splicing, and thereby provide a promising avenue for clinical therapeutics. Angelman Syndrome (AS), caused by loss-of-function of maternal UBE3A , has emerged as a monogenic neurodevelopmental disorder for which ASO therapy might be particularly amenable due to genomic imprinting. In an AS mouse model, Ube3a reactivation of the paternal allele using ASOs has been previously shown to rescue disease-relevant phenotypes. However, the poor sequence homology between murine and human UBE3A-ATS requires a human model system for screening of ASOs with clinical therapeutic potential. Here we evaluate an ASO targeting UBE3A-ATS using human induced pluripotent stem cell (hiPSC)-derived AS neurons in vitro and in vivo . We assessed the effect of ASO-treatment on cultured AS patient hiPSC-derived neurons through protein and RNA expression analysis. To increase clinical translatability, we designed a platform to evaluate this ASO in vivo by xenotransplantation of hiPSC-derived AS neurons into the brains of neonatal mice, with intracerebroventricular administration of the UBE3A-ATS ASO three weeks later. One week after ASO treatment, we observed in vivo reinstatement of UBE3A expression in xenotransplanted human neurons. These results highlight the potential for a versatile platform to evaluate efficacy of human-specific ASOs, for which AS provides an instructive proof-of-concept for therapeutic reactivation of UBE3A.

Dual quasi-bound states in the continuum in terahertz metasurfaces for high-Q resonance and multi-modal behavior

Bound states in the continuum (BICs) suppress radiative leakage and enable high-Q resonances for terahertz (THz) photonics. Here, we propose a metallic quadrumer metasurface in which dual quasi-BICs are efficiently excited via translational-symmetry perturbations, while preserving the overall C4v symmetry, leading to polarization-insensitive operation. The two resonances originate from distinct BIC mechanisms, namely, a Γ-point symmetry-protected BIC and a Friedrich–Wintgen BIC arising from modal interference, and evolve into coexisting Fano and electromagnetically induced transparency (EIT)-like responses within the same design. Notably, the resonance frequencies remain nearly unchanged across the perturbation range, indicating strong spectral robustness due to negligible variation of the metasurface’s effective refractive index. Terahertz time-domain spectroscopy (THz-TDS) measurements show consistent overall trends with simulations, while discrepancies in Q-factor and spectral contrast are mainly attributed to metallic loss and fabrication/measurement non-idealities. This work provides a compact route toward polarization-robust, multi-mode high-Q THz metasurface devices for filtering, sensing, and dispersion control.